Engine Titanium Consortium - Center for Nondestructive Evaluation ...

Engine Titanium Consortium 

Quarterly Report 

Lisa Brasche, ISU 

Tim Duffy, AS 

Jon Bartos, GE 

Kevin Smith, P&W 

Hans Weber, Facilitator 

on behalf of the Engine Titanium Consortium team 

February 8, 2000

TABLE OF CONTENTS 

SUBTASK 1.1.1: FUNDAMENTAL PROPERTY MEASUREMENTS FOR NICKEL BILLET.................................2 

SUBTASK 1.1.2: INSPECTION DEVELOPMENT FOR NICKEL BILLET ........................................................11 

SUBTASK 1.2.1: INSPECTION DEVELOPMENT FOR TITANIUM BILLET ....................................................17 

SUBTASK 1.3.1: FUNDAMENTAL PROPERTY MEASUREMENTS FOR TITANIUM FORGINGS......................25 

SUBTASK 1.3.2: INSPECTION DEVELOPMENT FOR TITANIUM FORGINGS ...............................................31 

SUBTASK 2.1.1: DEVELOPMENT OF UT CAPABILITY FOR INSERVICE INSPECTION .................................39 

SUBTASK 2.1.2: EDDY CURRENT PROBE EVALUATION AND IMPLEMENTATION....................................48 

SUBTASK 2.2.1: APPLICATION OF ETC TOOLS IN OVERHAUL SHOPS - EC SCANNING...........................56 

SUBTASK 2.2.2: HIGH SPEED BOLTHOLE EDDY CURRENT SCANNING...................................................64 

SUBTASK 2.2.3: ENGINEERING STUDIES OF CLEANING AND DRYING PROCESS IN 

PREPARATION FOR FPI ...............................................................................................68 

TASK 3.1: POD METHODOLOGY APPLICATIONS....................................................................................74 

SUBTASK 3.1.1: POD OF ULTRASONIC INSPECTION OF BILLETS ...........................................................74 

SUBTASK 3.1.2: POD OF ULTRASONIC INSPECTION OF TITANIUM FORGINGS........................................90 

SUBTASK 3.1.3: POD OF EDDY CURRENT INSPECTIONS IN THE FIELD ................................................100 

ETC PROGRAM MANAGEMENT...............................................................................................................108 

ETC PHASE II – Quarterly Report – October 1, 1999 - December 31, 1999 - Page 1 

print date/time: 01/31/00 - 9:39 AM 

ETC Proprietary Information –For internal ETC and FAA use only

Project 1: 

Task 1.1: 

Subtask 1.1.1: 

Production Inspection 

Nickel-based Alloy Inspection 

Fundamental Property 

Measurements for Nickel Billet 

Team Members: 

AS: P. Bhowal, Prasana Karpur 

ISU: Frank Margetan, Bruce Thompson, 

Ron Roberts 

GE: Ed Nieters, Mike Gigliotti, Lee 

Perocchi, Rich Klaassen 

PW: Jeff Umbach, Bob Goodwin, Andrei 

Degtyar 

Students: none 

Program initiation date: June 15, 1999 

Objectives: 

• To establish the basic ultrasonic properties of nickel-based alloy billet materials (Expected to be 

IN718, and one or more of Waspaloy, IN901, R95, or IN100) and relevant inclusions as an 

appropriate foundation for selection of ultrasonic inspection approaches. 

• To manufacture and characterize flat bottom hole (FBH), synthetic inclusion, and real defect 

standards to provide data for determining defect detectability and developing improved 

inspections. 

• To improve the understanding of the relationship of defect size, shape, and composition on defect 

detectability in Ni alloys. 

Approach: 

Alloy selection: Several alloys have been selected for fundamental property measurements with 

IN718 selected to receive the primary focus. Alloys to be considered include Waspaloy, IN100, IN901, 

and R95. Sample design and fabrication for properties measurements will be initiated by the team 

members. A list of the types of melt-related defects encountered at the billet stage in Ni-based alloys, 

defect morphology in the forged condition, and importance to life management will be generated by 

RISC. The importance of defect parameters (size, concentration, morphology, presence of voids) on 

detectability and life will be determined through discussion with the lifing and materials communities. 

(Nieters, Karpur, Gigliotti, Umbach, Goodwin, Margetan) 

Sample fabrication: The sequence of manufacturing the properties specimens and the specimen 

configuration will be planned to yield as much data as possible on properties as a function of depth 

and orientation. Novel configurations of coupons, and sequences of coupon extraction and 

characterization will be considered. Sample fabrication procedures will be coordinated with the 

Inspection Systems Capability Working Group to ensure use by both groups. (Umbach, Karpur, 

Nieters, Margetan) 




The proposed billet coupon scheme is shown 

in Figure 1. Because backscattered noise 

levels are strongly dependent on details of the 

metal microstructure, they can be used to 

guide the selection of coupon locations. 

From low and high noise regions, a "strip" 

specimen will be cut along the billet diameter, 

with transverse dimensions of approximately 

1.5" x 1.5". This specimen would initially be 

used for property measurements in the axial 

and hoop directions at various depths. The 

strip specimen would then be sliced into a 

series of coupons and be used for property 

measurements in the radial direction. The 

team will agree on the final specimen 

configuration early in the program, using the 

approach described here as a starting point. 

Similar schemes will also be used to study 

ultrasonic properties in the axial and hoop 

directions as a function of position. Results of 

the anisotropy measurements will be 

provided to the Inspection Systems Capability 

Working Group for incorporation into the 

noise models and ultimately will be used to 

predict the change in POD as a function of 

position. The data will also provide guidance 

in design of transducers and optimal 

inspection parameters for nickel billet in 

subtask 1.1.2. 

Axial Position 

Billet 

Hoop 

Measurement 

Axial 

measurement 

“Strip” 

Specimen 

(~ 1.5” x 1.5” x D) 

(b) 

High 

Noise 

Ref. 

Mark 

Circumferential Position 

(a) 

Radial 

Measurement 

Low 

Noise 

2nd-stage coupons 

Figure 1. (a) C-scan map of backscattered noise 

versus position, showing locations of high-noise and 

low-noise "strip" specimens. (b, c). Specimen and 

smaller sub-coupons will be used to study depth 

dependence of ultrasonic properties in the three 

orthogonal inspection directions. 

(c) 

Ultrasonic property measurements: Baseline ultrasonic properties (velocity, attenuation, and 

backscattered noise) of nickel billets will also be gathered for determination of the impact of properties 

on inspectability. Samples will be selected to address beam variability, with the expected sample set 

to include approximately 16 samples for each alloy. In Phase I, the ultrasonic properties of titanium 

billets were found to vary with position and inspection parameters, and similar variations are expected 

in nickel alloy billets and forgings. Selection of billets for properties specimens will be based on an 

initial screening inspection. Ultrasonic property measurements of the base alloys will provide the 

necessary noise distribution data for use by the Inspection Systems Capability Working Group in 

generating POD estimates for nickel billet. Signal distributions will be generated using FBH, 

synthetics, and the natural defects fabricated as defined above. Data on the natural defects will be 

used to develop and validate the flaw response and noise models and to generate the POD estimates 

for nickel billet in 3.1.1. 




Measurements on billet coupons will allow the team to assemble a more comprehensive picture of 

ultrasonic property variations within the billet, and to better understand the effect of these variations on 

inspectability. Correlations will be sought between the property variations with variations in the metal 

microstructure as revealed by optical micrographs and SEM studies. After assessing the findings for 

the first billet studied, the coupon manufacturing procedure will be refined as necessary for 

subsequent billets and forgings. (Margetan, Keller, Umbach, Karpur, Nieters) 

Synthetic inclusion samples: Synthetic inclusions will be embedded into Ni test standards for the 

purpose of evaluating the inspection sensitivity of ultrasonics on melt-related defects. The team will 

review the findings from the metallurgical analysis on the naturally occurring defects to identify the 

candidate inclusion types for sample manufacture. Construction methods will be developed at 

GE-CRD to chemically manufacture the synthetic inclusions and to embed the inclusions into Ni alloy 

test blocks. After the successful development of synthetic inclusion manufacturing methods, three 

blocks containing synthetic inclusions of different geometry and composition will be manufactured. 

The types of inclusions will be determined by the team based on the ability to manufacture the 

synthetic inclusions, the criticality of the defect to part life, and the sensitivity of the inspection to the 

composition and geometry of the defect type. 

The team will ultrasonically evaluate the synthetic inclusion samples to determine the sensitivity of the 

inspections for detecting and characterizing melt-related defects. This data will be used for the 

validation of computer-based flaw models and for the generation of POD curves for Ni alloy billets. 

(Gigliotti, Perocchi, Keller, Thompson, Margetan, Umbach, Karpur, Nieters) 

Defect characterization: Samples will also be acquired with real defects potentially to include dirty 

white spots, segregation (freckles), and slag (from ESR), reflecting both VIM/VAR and VIM/ESR/VAR 

material defects in 718 and Waspaloy. The initial effort will focus on evaluation of natural defects to 

establish typical compositions and properties and their detectability. Six samples will be evaluated 

using a limited ultrasonic characterization and a simplified metallographic process. Ultrasonic 

measurements will be performed at two stages: 

• original samples prior to sectioning 

• defects machined to regular shapes 

Characterization data will be used to optimize the inspection development efforts of 1.1.2, provide data 

for validation of flaw models and provide input for generation of POD for nickel billet in 3.1.1. Results 

will be included in the final report. (Thompson, Margetan, Keller, Klassen, Leach, Umbach, Karpur) 

Objective/Approach Amendments: Objective and approach remain as originally proposed in July 

1998. 

Progress (October 1, 1999 –December 31, 1999): 

Several Consortium conference calls were conducted during the quarter to discuss details of the 

Subtask. A number of technical issues were discussed and some decisions reached. The technical 

issues and discussions are summarized below: 




Test Materials - Discussions with Pratt & Whitney and the Waspaloy billet suppliers indicated that 

essentially all of the Waspaloy procured for rotating components is fabricated using the GFM 

conversion practice. Therefore, it was decided to use this manufacturing process to fabricate test 

samples. Pratt & Whitney has started making inquiries into procurement of billet material for the 

Waspaloy test specimens. This action completes the remainder of the 3 month milestone. 

RISC Input – Bill Knowles of the RISC Committee provided a report describing the Committee’s input 

on nickel defects. This report, combined with Mike Gigliotti’s list of melt related defects, will serve as 

the list of defects to be considered for study in this subtask and also completes the first half of the 6 

month milestone. 

Natural Defects – A telecon was completed between ETC Team members, nickel billet suppliers 

Allvac (John Long, Larry Jackman, and Viic Lowrey) and Special Metals (Rich Bobrek), and Sandia 

National Lab representative Jim Van Den Avyle to discuss natural flaws in nickel billet. The primary 

objectives of the telecon were to confirm the types of flaws commonly seen in nickel billets and also to 

determine if the different flaw types could be distinguished by ultrasonic inspection. Initial discussion 

was a description of flaws that occur in Ni billets. The following is a summary of each defect type that 

was discussed: 

Clean White Spots - grains that are diminished in interdendritic fluid elements (Nb and C in IN 718, Ti 

and C in Waspaloy TM ). The decrease is on the order of a few tenths of a percent; e.g., ~5% Nb 

instead of the nominal 5.2% Nb. These defects are not detected ultrasonically unless there is an 

associated crack or void. Typically they are identified by etch of a transverse section which is 

performed for each billet. 

Fibrous White Spots - large regions of depleted grains that can have dimensions on the order of 1/4". 

These are very rare. 

Dirty White Spots - grains that are severely depleted of interdendritic fluid elements (more so than 

Clean White Spots) and have a contaminant associated with them from the melt. The contaminants 

are usually oxides, nitrides or carbo-nitrides and there is usually a crack or void associated with dirty 

white spots. 

Freckles - grains that are rich in interdendritic fluid elements. These are very rare in occurrence (see 

less than one per year) and are not detected ultrasonically. 

Oxide/Nitrides - clusters of contaminant that are only detected ultrasonically by an associated crack or 

void. Alloying elements are not affected by their presence. 

Cracks/Voids - occur during the conversion process and do not always have a contaminant 

associated with them. 

Large Grains - grain growth that is generally near center for IN 718 but can occur near surface as well 

for Waspaloy TM . This is the only "defect" that has a characteristic UT signature which is a broad signal 

with increased background. 

Large Inclusions - pieces that fall into the melt but do not mix/melt as could occur with a large chunk 

of tungsten. Generally, a crack will be associated with these. 




It was concluded that only Large Grain defects could be pre-sorted by the UT response and that the 

other defects aren't identified until they are dissected. The driving force in the dissection is to 

determine if the defect is a freckle because that would have implications on the disposition of the heat. 

There are two consequences of this: (1) The investigations are not usually extensive if it can quickly be 

determined that the flaw is not a freckle; (2) There is not an existing supply of defects as each one has 

to be characterized before the parent material can be released. For ETC to acquire defects for 

sectioning, some arrangements will have to be made to disposition the parent material while the defect 

is under investigation. 

Both suppliers have databases for the defects that they have identified over the years which may be 

helpful in selecting defects by amplitude or depth. ISU has agreed to make a formal request of the 

suppliers for this information and they will determine to what extent they are able to reply. ISU is willing 

to enter into a nondisclosure agreement with the suppliers if that will help in release of the data. Bruce 

Thompson will take the lead on this action item. Since we are unable to pre-determine defect types 

from the UT response (other than large grain defects), it may be helpful to see if some variety of 

defects could be acquired based on position or amplitude. Towards this end, ISU may be able to 

suggest that the OEMs request defects by depth or amplitude rather than acquiring the first six defects 

that occur. Completion of this telecon marked the initiation of acquisition of natural defects for the 

subtask, and therefore completion of the remainder of the 6 month milestone. 

A number of modifications were suggested for the metallographic evaluation of the natural defects to 

be used by both GE and P&W. Andrei Degtyar prepared a final version of the procedure, which was 

approved by the subtask team. The details of the procedure are very similar to those used to evaluate 

the Contaminated Billet Study samples in Phase I. 

Synthetic Defect Preparation – Work continued at GE-Corporate Research Center on the development 

of manufacturing processes to prepare synthetic nickel defects. A literature survey was conducted to 

identify compositional ranges of naturally occurring defects in IN 718. Based on this literature search, 

freckle and white spot compositions were selected to generate synthetic defects. 

The IN 718 freckle and white spot compositions have been melted using induction skull cold crucible 

techniques and then directionally solidified into rods ~12mm diameter and 100mm long as shown in 

Figure 1. Samples have been machined for speed of sound and density measurements. Light 

microscopy and electron backscatter diffraction analysis have been performed to determine the 

constituent phases of the synthetic inclusions of the selected compositions. 

White spots are Nb- and Ti- lean regions in IN 718: There are two types, “dirty” white spots and 

“clean” white spots. So-called “dirty” white spots are generally contaminated drop-in of the crown or 

torus above the melt during vacuum arc re-melting. Clean white spots fall into one of several 

categories; Discrete white spots occur by drop in from crown or torus, dendritic white spots occur by 

drop in from shrinkage, and solidification white spots are thought to occur as a result of an instability in 

the solidification conditions during the final VAR process. Freckles are generally considered to be 

macrosegregation as a result of instabilities in the convective flow of Nb-rich liquid during 

solidification. The freckle regions typically possess higher volume fractions of Laves phase and/or δ- 

Ni 3 Nb. 




Figure 1 – Seeds of White Spot and Freckle Compositions produced 

using Clean Melt Cold Crucible Czochralski Crystal Growth 

Typical microstructures of the IN 718 microstructure and dirty white spot defects that have been 

prepared and are shown in Figures 2 and 3. 




Figure 2 – Typical Microstructure of IN 718 

Figure 3 – Typical Microstructure of a dirty 

white spot 

The freckle composition consists of primary Ni dendrites and an interdendritic eutectic of fine-scale Ni 

and Cr 2 Nb type C14 Laves phase as shown in Figure 4. 

Eutectic 

Ni Dendrite 

Figure 4 – Typical Freckle Microstructure showing Primary Ni 

Dendrites and an Interdendritic Eutectic 

Plans (January 1, 2000 –March 31, 2000): 

Continue acquisition of IN 718 and Waspaloy test specimen material 

Continue development of synthetic defect manufacturing methods 




Milestones: 

Original 

Date 

Revised 

Date 

Description Status 

Fundamental properties of nickel billet 

3 months 6 months 

(Waspaloy) 

6 months 

(Waspaloy) 

Finalize sample configuration and manufacturing 

sequence. (All) 

Initiate sample fabrication. (GE, PW; GE to 

supply IN718, PW to supply Waspaloy) 

6 months Coordinate with RISC to generate list of 

melt-related defects and provide to Inspection 

Development and Inspection Systems Capability 

teams. Identify preferred defect types for study. 

Initiate acquisition of naturally occurring 

melt-related defects. (All) 

18 months Evaluate natural defects to determine needed 

synthetic defects. Establish methods for 

manufacturing synthetic defects and for 

embedding synthetic and natural defects in IN718. 

(GE) 

24 months Complete property measurement samples. (GE, 

PW) 

36 months Complete synthetic inclusion standards with 

representative variation in type, geometry, and 

chemistry. (GE) 

36 months Complete characterization of property samples 

and provide to 3.1.1 for development of flaw 

response and noise models and for generation of 

the noise distribution for nickel. Includes 

ultrasonic velocity, attenuation, noise, 

microstructure. (ISU with support from GE, 

PW,AS) 

42 

months 

24 - 42 

months 

Coordinate results with 1.1.2 in the inspection 

design and implementation. (ISU with support 

from GE, PW,AS) 

Report of ultrasonic properties (sound 

velocity, attenuation, and backscattered 

noise) and types of defects of concern in 

IN718 , Waspaloy, and IN901. (All) 

Validate noise models in cooperation with 3.1.1. 

(All) 

42 months Complete ultrasonic characterization of 

melt-related defects and provide results to 3.1.1. 

(All)) 

54 

months 

Report of characterization of defects and 

ultrasonic properties (sound velocity and 

acoustic impedance) as a function of 

composition for defects in IN718. (All) 

60 months Representative sample blocks and synthetic 

inclusion samples (All) 

Complete 

Complete 




Deliverables: 

Original 

Date 

Revised 

Date 


Fundamental properties of nickel billet 

42 months Report of ultrasonic properties (sound velocity, 

attenuation, and backscattered noise) and types of 

defects of concern in IN718, Waspaloy, and IN901 

54 months Report of characterization of defects and 

ultrasonic properties (sound velocity and acoustic 

impedance) as a function of composition for 

defects in IN718 

60 months Representative sample blocks and synthetic 

inclusion samples 

Metrics: 

Assessment of ultrasonic properties for typical nickel alloys and characterization of melt-related 

defects that support the needs of inspection development, POD estimation, and life management. 

Major Accomplishments and Significant Interactions: 

Date 

Description 

June 16, 1999 Technical Kick-off Meeting in West Palm Beach, FL 

December 21, 

1999 

Telecon with Special Metals, Allvac, and Sandia National Lab personnel to discuss their 

experience with Ni defects and initiate discussions on obtaining natural Ni defect samples 

Publications and Presentations: 

Date 

Description 




Project 1: 

Task 1.1: 



Nickel-based Alloy Inspection 

Inspection Development for 

Nickel Billet 

Team Members: 

AS: Andy Kinney, Prasana Karpur 

ISU: Ron Roberts, Bruce Thompson, Frank 

Margetan 

GE: Bob Gilmore, Ed Nieters, Mike 

Danyluk, Mike Keller 

PW: Jeff Umbach, Bob Goodwin, Dave 

Raulerson, Andrei Degtyar 



Objectives: 

• To apply technology developed in Phase I for titanium billet inspection to improve nickel billet 

inspection. 

• To perform factory inspection of approximately 100,000 pounds of nickel alloy billet, primarily 

INCO718, to #1 FBH sensitivity using a multizone inspection system with digital acquisition to 

provide necessary field experience that facilitates implementation decisions. 

• To determine applicability of multizone technique to Waspaloy. 

• To provide the billet industry and OEMs with demonstration of improved sensitivity inspection 

using FBH standards as the metric with a goal of #1FBH sensitivity in 10” INCO718 billets and 

Waspaloy billet. 

• To provide necessary data to the Inspection Systems Capability team for estimation of POD for 

nickel billet, including cut-up data generated in the pilot lot inspection. 

Approach: 

Initial assessment: A kickoff meeting involving the subtask team members will be held at the program 

onset to reiterate the plans of the task and establish a means of sharing information and data, 

including necessary support of Task 3.1.1. The current plan of concentrating on INCO718 and 

Waspaloy to sensitivities of #1FBH and #2.5FBH sensitivity respectively will be verified as the correct 

targets and requirements for signal-to-noise measurements will be determined. The number and 

types of calibration standards will be discussed and design of the standards will be initiated. Any 

significant change agreed on by the team will be presented to ETC management. (All) 

Production calibration standards for the nickel alloys, presumably 10” diameter, as agreed upon in the 

initial planning meeting will be manufactured. An evaluation of current capability of conventional 

inspections will be performed as a baseline for both INCO718 and Waspaloy using the production 

calibration standards rather than relying on the nominal values stated in respective specifications. 




Small diameter billet assessment: Assessment of small diameter inspection will also be completed by 

AlliedSignal. AlliedSignal will perform studies using billets of < 8” diameter The objective will be to 

apply technology developed in Phase II for larger Ni billet to improve nickel billet inspection in the 

stated diameter of interest to small engine manufacturers. Feasibility demonstration will be conducted 

in the laboratory environment using small nickel alloy billet and multizone transducers developed for 

the smallest of the large diameter billets. Sensitivity analysis (#FBH) will be conducted for various 

small diameter billets. A comparison will be made with the standard spherical focus approach. 

Results will be provided to the Inspection Systems Capability Working Group to allow POD estimates. 

(Keller, Leach, Umbach, Kinney, Keiser, Duffy, Thompson) 

Baseline assessment: Inspection development will be performed with the calibration standards using 

existing multizone transducers to occur at PW and GE facilities to ensure hands-on involvement by the 

parties responsible for final implementation recommendations. Scans and associated measurements 

will be used to determine the focal depth of each transducer, measure the axial beam profile and 

beam cross-section, and compare these results to model predictions. Signal-to-noise ratio will be 

determined for the FBH targets. The need for new transducers will be evaluated based on these 

scans and model results. (Keller, Gilmore, Nieters, Umbach, Raulerson, Goodwin, Kinney, Karpur, 

Roberts, Gray) 

New transducers will be designed and built if results indicate that the existing transducers do not 

produce a focal zone at the required depth or of the required beam diameter, and if modeling indicates 

that significant improvement could be obtained by re-design. Additional funding will be sought for 

transducer fabrication at that time if the team agrees that the proposed benefits are substantial. 

(Keller, Umbach, Goodwin, Karpur, Roberts) 

Laboratory demonstration: After inspection development for each alloy is completed, a laboratory 

demonstration of billet inspections with optimized transducers will be provided for the ETC members. 

Sensitivity to #1FBH in INCO718 and to #2.5FBH in Waspaloy will be demonstrated and plans made 

for pilot inspection. (Keller, Nieters, Leach, Umbach, Goodwin, Kinney) 

Factory demonstration: A factory pilot inspection of approximately 100,000 pounds will be planned to 

determine the sensitivity level that can be consistently achieved in production and to identify any 

barriers to implementation. The first step will be for the team to identify an industry partner(s) to 

perform the pilot inspection, much as RMI worked with the consortium in Phase I in the inspection of 

titanium billet. A detailed plan will identify the particular specifications of INCO718 to be inspected, 

i.e., VIM/VAR and/or VIM/ESR/VAR, and the number of material suppliers. Investigations performed 

in the nickel fundamental studies Task 1.1.1, will provide information to determine the need to include 

two types of INCO718 in the pilot inspection. If the defect types found in the two materials and the 

ultrasonic characteristics are the same, then there will not be a need to include both in the factory pilot 

inspection. The extent of inclusion of Waspaloy will also be planned. Procedures for inspection, 

evaluation of data, and investigation of indications will be defined. It is expected that eight finds will be 

cut-up and evaluated using a process similar to that described in AC 33.15. It is expected that each 

OEM will participate in the destructive characterization of indications with two planned for Waspaloy 

and six planned for IN718. The team will also agree on parameters needed to determine the cost 




impact of implementing the higher sensitivity inspection as compared to conventional inspection. 

(Keller, Gilmore, Nieters, Leach, Umbach, Goodwin, Smith, Kinney, Keiser, Roberts, Thompson) 

The pilot lot evaluation of 100,000 pounds of billet with the optimum transducers will occur in 

cooperation with a multizone inspection source and nickel alloy material suppliers. Evaluation of 5 to 

10 heats of material is expected. Since application of multizone technique is expected to be more 

straightforward for INCO718, most of the pilot work will be performed with that alloy. The application 

of #2.5FBH sensitivity to Waspaloy is expected to be more complex but an inspection technique 

should be ready to substitute for the last 25% of the pilot lot. The data will be evaluated and reported. 

Results of the pilot inspection and of any cut-ups will be provided to Task 3.1.1 for use in developing 

POD estimates for nickel billet. Cost and detection sensitivity assessments necessary for life 

management and implementation decisions will be gathered. Components of cost assessment will 

have been agreed on by the team and will likely include such items as system cost, longevity of 

equipment, recurring equipment costs, daily operational/inspection costs, and costs associated with 

false calls. In conjunction with the pilot lot inspection, a demonstration of the higher sensitivity 

inspection for INCO718 and Waspaloy will be presented to the OEMs and industry. A final report in 

the required FAA format will be provided. (Keller, Gilmore, Nieters, Leach, Umbach, Goodwin, Smith, 

Kinney, Keiser, Roberts, Thompson) 


1998. 





Conventional Nickel Inspection – In order to measure improvement in the multizone inspection 

technique to be developed in this subtask, baseline conventional inspection processes must be 

defined. The baseline inspection process for Waspaloy was discussed by Pratt & Whitney and 

Honeywell. It was decided that the baseline process would be essentially as defined in the Pratt & 

Whitney billet inspection specification. 

IN718 Calibration Standard –GE initiated procurement of two sections of 10” diameter IN 718 billet, 

one prepared using the GFM process and the other using the V-Die block process. The grain size 

requirement for the billets was changed to ASTM #5 or finer with less than 20% being ASTM #2 to be 

consistent with specifications for production material of 8” diameter or greater. The two billets will be 

ultrasonically inspected using backwall amplitude monitoring to compare material attenuation 

properties. This data will be used to determine if a single standard can be used to represent the 

ultrasonic characteristics of both conversion processes. 

Waspaloy Calibration Standard – The GFM conversion process was selected as the most 

representative for Waspaloy used in rotating components. Pratt & Whitney will procure 10” diameter 

Waspaloy from Allvac for the calibration standard. The configuration of the Waspaloy calibration 

standard will be identical to that of the IN 718 standard shown in the previous quarterly report except 

the calibration holes will be #2.5 and #3 Flat Bottom Holes. 




Small Diameter Billet - Honeywell has selected Waspaloy as the material to be evaluated in the small 

diameter billet study. The calibration standard will be patterned after the standard used for 10” 

diameter billet and tentatively contain #1 and #2 Flat Bottom Holes. 


Continue acquisition of material for IN 718 and Waspaloy calibration standards 

Complete design of small diameter billet calibration standard 




Milestones: 

Original 

Date 

Revised 

Date 


Nickel billet inspection development 

3 months Kickoff meeting to verify selection of materials and 

target sensitivities, initiate design of calibration 

standards and establish metrics for cost and 

sensitivity assessment. Coordination with 

Inspection Systems Capability Working Group will 

occur to ensure necessary data for later POD 

studies. (All) 

24 months Assessment of sensitivity for small diameter billet. 

Data to be provided to Task 3.1 to enable POD 

assessment. (AS) 

24 months Complete modeling and laboratory testing of 

existing transducers on calibration standards for 

INCO718 and assess need for new transducers. 

(GE, ISU). 

24 months Complete modeling and laboratory testing of 

existing transducers on calibration standards for 

Waspaloy and assess need for new transducers. 

(PW, ISU) 

18 months Complete calibration standards. (GE, PW) 

22 months Assessment of conventional inspections for 

baseline. (GE, PW). Data to be provided to Task 

3.1 to enable POD assessment. (All) 

24 months Complete logistics of pilot lot inspection including 

establishing agreements with multizone inspection 

source and billet suppliers and establishing means 

of acquiring necessary cost data. (GE, PW) 

30 months Perform laboratory demonstration for ETC 

members. (GE, PW) 

36 months Complete factory evaluation of approximately 

100,000 pounds of billet Perform demonstration 

for OEMs and industry at inspection facility. (GE, 

PW, ISU) 

38 months Evaluate any finds to determine necessary size 

parameters for POD assessment. (GE, ISU, PW) 

42 months Complete cost comparison of higher sensitivity 

multiple zone inspection with conventional 

inspection. (GE, PW) 

55 months Complete final report including sensitivity and cost 

comparison assessments. (All) 

55 

months 

60 

months 

Report of laboratory and factory 

evaluations including sensitivity data for 

use by the Inspection Systems Capability 

Working Group and cost assessments. 

Calibration standards and fixed focus 

transducers. 

Calibration standards and fixed focus 

transducers. 

Complete 




Deliverables: 

Original 

Date 

Revised 

Date 


38 months Laboratory demonstration and factory evaluation 

of multizone inspection including supplier 

demonstration. 

55 months Report of laboratory and factory evaluations 

including sensitivity data for use by the Inspection 

Systems Capability Working Group and cost 

assessments. 

60 months Calibration standards and fixed focus transducers. 

Metrics: 

Demonstration of #1FBH sensitivity inspection for INCO718 billet up to 10” diameter and #2.5FBH 

sensitivity for Waspaloy up to 10” diameter. 

Factory demonstration will include target of 90 cubic inches per minute scanning rate for multizone 

inspection. 


Date 

Description 



Date 

Description 




Project 1: 

Task 1.2: 



Titanium Billet Inspection 


Titanium Billet 

Team Members: 

AS: Prasana Karpur, Andy Kinney, R. 

Krantz 

ISU: Bruce Thompson, Ron Roberts, Frank 

Margetan 

GE: Dave Copley, Bob Gilmore, Al 

Klassen, Wei Li, Mike Keller 

PW: Kevin Smith, Dave Raulerson, Jeff 

Umbach, Bob Goodwin, Andrei Degtyar 



Objectives: 

• To provide a procedure to account for attenuation effects such that the variation between 

calibration and inspection sensitivity is minimized. 

• To demonstrate the ultrasonic equipment and techniques required to inspect titanium alloy billets 

to #1FBH sensitivity for 10” diameter and below. 

• To provide an initial assessment of sensitivity at diameters greater that 10”. 

Approach: 

Transducer design models: The design models will be reevaluated in detail to determine reasons for 

discrepancies between predicted and measured transducer behavior observed during Phase I work. 

This reevaluation will focus initially on assessing how well the input parameters used for the models 

represent the physical behavior of the transducers. It is planned to begin with characterization of 

piezo-electric elements prior to the addition of backing materials, and then attempt to compare model 

predictions with experiment at subsequent stages of the manufacturing process. This will involve 

working closely with a transducer manufacturer with one potential source identified. Based on this 

exercise, modifications will be made to model input parameters or to the model code to improve the 

prediction accuracy. Attention will also be paid to selection of transducer materials with consistent and 

measurable properties, for example the machining of lenses from solid material rather than using 

cast-in-place epoxy. Results will be shared with transducer manufacturers to allow improvements in 

future products both for ETC and the broader ultrasonic transducer user community. (Roberts, 

Margetan, Li, Umbach) 

Inspection of 10” diameter billet: Fixed focus inspection will be the primary technique in this task. If 

this approach proves inadequate to meet program objectives, viable phased array technologies will be 

reviewed to select a candidate technique with the most potential for meeting the program objectives in 

consultation with the FAA. 




Improved fixed focus transducers for 10” diameter billet will be designed. Results from Phase I 

measurements (at 2.25” and 4.05” depths) will be used to identify the best combination of focal spot 

diameter and frequency, and this information will be used to design the complete set of transducers. 1 

Phase I work indicates that frequency and bandwidth should be increased from those of the current 

production transducers which are 5MHz frequency and approximately 50% bandwidth. (Roberts, 

Margetan, Umbach, Keller, Copley, Li, Leach) 

Two sets of the improved-design transducers will be purchased. A distance-amplitude correction 

(DAC) capability for the multizone instrumentation is being developed external to the ETC program 

with details to be shared with the ETC. This is expected to improve sensitivity by 1 or 2 dB by 

ameliorating the current situation where high noise in the focal plane of the transducer limits sensitivity 

at the near and far ends of the depth-of-field. (Keller, Umbach, Goodwin) 

Laboratory demonstration on 10” diameter billet: Scans will be performed on the ETC 10” diameter 

standards using the above transducers, and with DAC capability added to current multizone 

instrumentation. Work will be performed at GE QTC, with support provided to other Consortium 

members to participate in the measurements. The FBH amplitudes, noise levels, and FBH 

signal-to-noise ratios will be evaluated and compared with measurements made on production 5MHz 

transducers during Phase I. A determination will be made of whether sensitivity level meets the 

#1FBH goal in all regions of the billet. Results will be provided to 3.1.1 for incorporation in the 

modeling and reliability efforts. (Keller, Leach, Copley, Umbach, Goodwin, Karpur) 

AlliedSignal will also perform a sensitivity assessment on smaller diameter billets using billets of

on these approaches will be limited to building one sensor assembly for each approach if suitable 

sensors are not already available for loan by the OEMs. The evaluation will concentrate on performing 

scans of the center region (3.5” to 5.5” depth), using the ETC 10” diameter standards. Evaluation of 

DFATS will be performed at PW, evaluation of the R/D Tech system will be at GE, and evaluation of 

any other systems would be at a location to be agreed upon by the technical team. Arrangements will 

be made to accommodate full team participation for all of these evaluations. The laboratory scan 

results will be reviewed to identify a preferred configuration for factory demonstration and potential 

implementation. The review will consider inspection performance, equipment cost and complexity, 

operating speed, and other implementation factors. A hybrid system using fixed focus for the outer 

zones and phased array for the center will be considered as part of this evaluation. (All) 

If the final approach agreed to by the technical team for factory demonstration includes phased arrays, 

additional work will be done to refine the sensor design for the selected array approach. 

Manufacturer’s engineering specifications for the array system design (element geometry, lens/mirror 

geometry, etc.) will be input into an array system computational simulation. Theoretical system 

performance will be compared to laboratory measurements of array system response. Discrepancies 

between model and experiment will be traced to underlying causes and resolved. Models will then be 

used to optimize the design and set up for specific test standards targeted for study including larger 

diameter billets. (Roberts, Umbach, Keller, Karpur) 

Factory evaluation: The multizone configuration will be used to perform factory evaluation of five 

heats of 10” diameter titanium at a production inspection facility. Cost and detection sensitivity 

assessments necessary for life management and implementation decisions will be gathered. 

Components of cost assessment will include such items as system cost, longevity of equipment, 

recurring equipment costs, daily operational/inspection costs, and costs associated with false calls. 

Evaluation will include cut-ups of any finds. Details of metallography will depend on how many 

indications are found, but it is anticipated that all finds will be evaluated to determine cause, and one 

will be step-polished to obtain detailed sizing information. (Keller, Leach, Klassen, Umbach, 

Thompson, Smith) 

Factory demonstration: An industry-wide demonstration of the multizone system will be scheduled. 

OEMs and titanium billet producers will be invited. (Brasche, McElligott, Klassen, Umbach, Raulerson, 

Roberts, Karpur) 

Assessment of large diameter billet (>10” dia): Assessment of the sensitivity at larger diameters will 

use 13” and 14” diameter standards. Existing 13” standards will be used, and a 14” chord block 

standard with near-centerline targets will be designed and built. Initial assessment will be made to 

baseline conventional inspection sensitivity either using transducers borrowed from suppliers, or by 

requesting suppliers to perform the evaluation in-house. Evaluation of zoned fixed-focus capability will 

use existing multizone transducers. Evaluation will follow a plan to be agreed by consortium 

members. If the targeted 4x sensitivity improvement over conventional inspection has been achieved 

for 13” and 14” diameters, the results will be documented and no further work pursued. If 

improvement is still needed, a plan will be formulated following the best approaches (phased array or 

improved fixed focus) identified for 10” diameter billet. The plan will be presented to the FAA as 




continued work is expected to require funding redirection. (Umbach, Goodwin, Raulerson, Smith, 

Keller, Klassen, Leach, Roberts, Thompson) 

Attenuation compensation procedures: The current procedures used to measure and compensate for 

material attenuation will be evaluated and improved. The current procedure for the multizone 

inspection uses a pre-inspection of four short sections (1” long) of the billet to obtain an average 

backwall echo amplitude. This is compared with an average backwall amplitude measured on the 

calibration standard and the difference is used to calculate an attenuation compensation factor in 

decibels per inch. A transducer focussed at the billet center is used to make the measurements. The 

drawback of this method is that it ignores the effects of distortion of the ultrasonic beam during 

propagation through the metal microstructure. Phase I work has shown that beam distortion can be a 

major contributor to the response from flaws and backwalls. Even when beam distortion effects are 

minor and energy loss dominates, the material attenuation is found to vary significantly with position in 

a given billet in conjunction with noise banding as was shown in Figure 6. The effects of noise 

banding and nonuniform attenuation can lead to an incorrect measurement of flaw response, and a 

true inspection sensitivity different from that assumed from calibration. The current attenuation 

compensation technique will be evaluated by applying it to several billet segments, then drilling a 

number of flat-bottom or side-drilled holes into the sections, and comparing the measured amplitudes 

of those holes to those expected from the attenuation analysis. Improvements will focus on selection 

of a transducer which will minimize the effects of beam distortion and provide an attenuation estimate 

which enables good prediction of the hole echo amplitudes. (Margetan, Klassen, Leach, Li, Umbach) 

Billet specification: The specification for billet inspection (AMS 2628) will be updated to reflect 

improvements achieved by this subtask. Results will also be reported in required FAA format. 


1998. 





Transducer Modeling -- Work is addressing an apparent discrepancy between theoretically predicted 

and experimentally measured transducer focal properties. Specifically, work in ETC Phase I used 

transducer radiation models to specify fabrication geometry. There it was noted that transducers 

procured from a manufacturer were consistently focusing short of model predictions. Current work is 

seeking an explanation for this discrepancy. In an internally funded GE activity, transducers are 

currently being procured from several (four) manufacturers. Fabrication specifications for these 

transducers have been determined through use of the transducer radiation models. To date, 

transducer performance has been measured on transducers from three of these manufacturers. One 

manufacturer produced transducers that focused short of the model predictions. Another 

manufacturer produced transducers that focused slightly deeper than the model predictions. A third 

manufacturer produced a transducer that was in close agreement with model predictions. These 

results suggest that the underlying cause of the discrepancy lies in variability in manufacturing 




processes. A meeting is scheduled on 1/26/00 at the GEAE QTC involving interested ETC team 

members to discuss these results, and to formulate approaches to accommodate variability in 

manufacturing when determining procurement specifications. 

14” diameter Calibration Standard – Pratt & Whitney will procure Ti –6-4 material for a 14” diameter 

chord block standard using their current material specifications for grain size. The standard will 

contain two Flat Bottom Hole sizes, one representing the current conventional inspection requirement 

and one representing the sensitivity goal for the subtask. The chord block standard design will be 

based on the 13” diameter chord blocks prepared in Phase I. 


Continue to resolve transducer model discrepancies. Continue to use data from GE transducer 

procurement program to validate transducer model 

Prepare draft design for 14” billet chord block standard 




Milestones: 

Original 

Date 

Revised 

Date 


10” diameter fixed focus 

12 months Resolve model discrepancies and design 

transducers. (ISU) 

27 months Build transducers. (GE) 

29 months Complete scans on 10” standards and RDB. 

Provide data to 3.1.1 for estimation of POD. 

(GE,PW) 

30 months Review results, determine whether #1FBH goal 

was achieved. (All) 

34 months Design and build two transducers for 14” diameter 

center zone. (GE with support from PW) 

Evaluate performance on 14” chord block. (PW 

with support from GE) 

(30 

months) 

(33 

months) 

(39 

months) 

(42 

months) 

(48 

months) 

10” diameter phased array,(go/no go 

decision at 30 months) 

(Critical review with FAA, seek program redirection 

to develop phased arrays) (All) 

Complete preliminary phased array surveys. 

(PW) 

Evaluate up to three candidate phased array 

systems. 

Identify preferred configuration for factory 

evaluation system. 

Design and build improved phased array 

transducer assembly. 

Factory Evaluation / Demonstration 

36 months* Complete factory test of five heats. Conduct 

industry demonstration of #1FBH capability in 10” 

diameter. (GE, PW) 

38 months* Evaluate indication finds from factory test, 

document results. (GE, PW, ISU). 

40 

months 



use by the Inspection Systems Capability 

Working Group and cost comparisons for 

the different inspection approaches. (All) 

Large diameter billet 

12 months Build chord calibration standard for 14” diameter, 

near-center region. (PW) 

18 months Evaluate capability on 13” and 14” diameter using 

conventional and zoned fixed focus, determine 

improvement over conventional. Provide data to 

3.1.1 for model validation and POD estimation for 

large diameter billet. (GE, PW, ISU) 

20 

months 

Laboratory assessment of sensitivity at 

diameters greater than 10" diameter 

using fixed focus transducers. (All) 




Original 

Date 

(21 

months) 

Revised 

Date 


(Formulate plan for 13”/14” improvements and 

present to FAA if 4x improvement not achieved). 

(All) 

General issues 

28 months Complete attenuation compensation procedure in 

cooperation with 3.1.1. (ISU with support from 

PW and GE) 

30 

months 

60 

months 

60 

months 

Procedures to account for attenuation 

effects that occur in titanium billet and 

thus improve the POD of billet inspection. 

(All) 

Provide revision of AMS 2628 titanium 

billet specification to SAE Committee K. 

Calibration standards including 14" 

diameter chord block and transducers 

(fixed focus and phased array assemblies) 

as needed. 

* will be delayed by 18 months if phased array option pursued 

(Milestones shown in parentheses are not included in budget. Detailed budget will be formulated as 

part of launch decision.) 

Deliverables: 

Original 

Date 

Revised 

Date 


20 months Laboratory assessment of sensitivity at diameters 

greater than 10” diameter using fixed focus 

transducers. 

30 months Procedures to account for attenuation effects that 

occur in titanium billet and thus improve the POD 

of billet inspection. 




comparisons for the different inspection 

approaches. 

60 months Calibration standards including 14” diameter chord 

block and transducers (fixed focus and phased 

array assemblies) as needed. 

60 months Revision to AMS 2628 titanium billet specification 

submitted to SAE Committee K. 

Metrics: 

Achievement of #1FBH in 10” diameter billet with no significant speed reduction from current 

multizone inspection. 





Date Description 



Date 

Description 




Project 1: 

Task 1.3: 



Titanium Forging Inspection 

Fundamental Property 

Measurements for Titanium 

Forgings 

Team Members: 

AS: Prasanna Karpur, R. Bellows 

ISU: Bruce Thompson, Frank Margetan, 

Ron Roberts, Tim Gray, 

GE: Ed Nieters, Mike Gigliotti, Lee 

Perocchi, John Deaton, Bob Gilmore, Rich 

Klaassen, Dave Copley, Wei Li 

PW: Jeff Umbach, Dave Raulerson, Bob 

Goodwin, Gary Peters, Andrei Degtyar 



Objectives: 

• To gain the fundamental understanding of the ultrasonic properties of titanium forgings that is 

needed to provide a foundation for the development of reliable inspection methods that provide 

uniformly high sensitivity throughout the forging envelope. 

• To acquire the data necessary to relate the detectability of defects in forgings to component 

properties (flow line characteristics, surface curvature) and defect properties (size, shape, 

composition, location, and orientation) thereby providing a foundation for the design of improved 

inspections and the evaluation of inspection capability. 

Approach: 

Sample fabrication: A critical flaw list for titanium forgings will be generated in cooperation with RISC 

including description of typical morphologies for use in the model development efforts. This list will be 

used to define a limited set of forging standards with embedded defects. (Margetan, Thompson, 

Raulerson, Umbach, Nieters, Copley, Deaton, Gilmore, Karpur ) 

Forging samples with varying flow line characteristics and surface curvatures, some of which will 

contain flat-bottomed holes or synthetic inclusions will be defined and manufactured. Deformation 

models will be used to predict variations in metal flow distributions and guide the sample development. 

Approximately 32 coupons from forgings with varying flow line directions, flow line densities, and 

geometrical curvatures (concave and convex) will be acquired. Samples available from the CBS and 

TRMD programs will be utilized to the extent possible. (Copley, Gigliotti, Perocchi, Deaton, Nieters, 

Margetan, Thompson, Umbach, Raulerson, Karpur) 




Ultrasonic property measurements: UT and material anisotropy associated with the forging process 

will be quantified by measurement of the sound speeds, attenuations, signal fluctuations and 

backscattered noise levels of the forging coupons. The measurement methods developed in Phase I 

will generally be used. As in Phase I, cube specimens cut at various locations may be used for initial 

surveys. In selected cases, novel coupon geometries will also be considered which permit beam 

propagation at various angles to the flow lines. Figure 2 displays one possible coupon design which 

allows measurements: (1) along flow lines; (2) perpendicular to flow lines; and (3) at oblique 

incidence. Such measurements will be used to establish the relationship of flow line direction to 

inspectability. The results of the experimental measurements will be used to develop and validate the 

noise models and ultimately allow consideration of the effect of forging process on inspection 

capability as part of 3.1.2. (Thompson, Gray, 

Margetan, Neiters, Klassen, Gilmore, Umbach) 

Measurements will be made of the ultrasonic 

scattering from the embedded defects, 

including both the synthetic hard alpha 

inclusions and the samples available from the 

CBS and TRMD programs. This data will be 

provided for further model validation which will 

in turn be utilized in subtasks 3.1.2 for POD 

determination. 

Effects of surface curvature: The relationship 

between surface curvature and inspectability 

will be quantified in this subtask. The shape of 

the entry surface influences the focusing of the 

sonic beam within the forging, and hence, affects 

both the amplitude of defect echoes and the 

level of competing grain noise. The team will 

measure the effects of surface curvature by 

using coupon designs such as that shown in 

Figure 3. Curvature corrections will be 

developed and transducer designs will be 

optimized in cooperation with 1.3.2. Models 

which predict the effects of surface curvature on 

backscattered flaw echoes, grain noise 

characteristics, and signal/noise ratios will be 

developed and validated in cooperation with 

3.1.2. Measurements made using the 

surface-curvature specimens will be used to 

validate those models. The models will then be 

used to develop curvature corrections and 

optimized transducer designs for forging 

inspections in support of 1.3.2. (Gray, Margetan, 

Measurements 

parallel to 

flow lines 

FLOW LINES 

Initial Shape 

Oblique angle 

measurements 

Measurements 

perpendicular 

to flow lines 

Figure 2. Potential coupon design for forging samples. 

Octagonal shape provides entry and reflecting surfaces for 

velocity and attenuation measurements at various 

orientations to the forging flow lines. 

FBH’s 

A 

B 

C 

D 

E 

Surface 

Progression 

- 2” 

- 4” 

flat 

4” 

2” 

Figure 3. Potential design for surface curvature test 

specimens. Specimen contains flat-bottomed holes or 

other reflectors, and begins with a concave surface 

curvature which is progressively machined to arrive at 

convex entry surface. Design ensures that metal travel 

path and microstructure surrounding the reflectors remain 

unchanged in successive measurements. 




Roberts, Thompson, Li, Gilmore, Copley, Nieters, Umbach) 


1998. 





Test Sample Design – Discussions of the test sample designs continued during the monthly telecons. 

Four different types of test specimens were identified, as follows: 

1) Noise Curvature Blocks – the convex and concave radii blocks will be prepared from Ti-6-4 

material to the configurations shown in Figure 1. All these blocks will be prepared by Pratt 

& Whitney. The blocks will evaluate 6 different radii, 3 convex and 3 concave, and contain 

a total of 12 Flat Bottom Holes – 6 drilled at 0.75” depth and 6 drilled at 1.5” depth. 

2) Curvature Correction Blocks – these blocks will be made from powder metallurgy nickel 

alloy to minimize the microstructural noise. The blocks, to be made by GE, will tentatively 

contain 4 different radii 

3) Property/Flow Line Measurement Blocks – these blocks will be cut from the forgings 

supplied by the OEMs based on flow line and ultrasonic information. They will be prepared 

using Ti-6-4 material and will tentatively be cube shaped. GE will prepare 24 blocks and 

Pratt & Whitney will prepare 6 blocks. 

4) Synthetic Inclusion Disk – this Ti-6-4 disk (or partial disk) will contain embedded synthetic 

hard alpha defects. GE will embed the defects. The source and design of the disk are to 

be determined. 

• 2 depths (3/4” and 1.5”) 

• 6 #1 FBH’s at each depth 

• Concave radii: 0.75”, 2.0”, 8.0” 

Convex radii: 6.0”, 10.0” 

Figure 1 – Proposed design of Noise Curvature Blocks 




Significant discussion centered around the Noise Curvature Blocks. Frank Margetan accepted the 

proposed radii, but questioned the size and location of the Flat Bottom Hole targets. Pratt & Whitney 

agreed to run the modeling software to determine how much degradation will be caused by the curved 

surfaces and assist in the determination of what size Flat Bottom Holes should be used. 

Flowline Modeling - All OEMs have selected a forging to be used for test specimen fabrication. Each 

OEM will supply flow line information and ultrasonic noise data to Frank Margetan to allow him to 

compile a list of Property/Flow Line Measurement samples (location and geometry) to be cut from the 

forgings. It was decided that the 4 month and the 6 month milestones should occur simultaneously 

when Frank Margetan provides the list of Property/Flow Line Measurement samples. Although this 

could depend on the results of the ultrasonic data, these milestones are currently planned to be 

complete by month 8. 


Supply flowline and ultrasonic data to ISU for design of samples 

Complete design of Curvature Correction blocks 

Complete design of Noise Curvature blocks 




Milestones: 

Original 

Date 

Revised 

Date 


Flaw and sample definition 

3 months Generate critical flaw list for titanium forgings in 

cooperation with RISC and provide to 3.1.2. (All) 

4 months 8 months Utilize deformation model predictions to guide 

sample development. (PW with support from ISU) 

6 months 8 months Provide list of samples and sample geometry to be 

developed for forging property measurements. 

(ISU with support from GE, PW) 

Sample fabrication 

complete 

P&W complete 

Sample list complete – need 

UT and flowline data to 

finalize sample geometries 

12-30 

months 

Acquire/fabricate the necessary samples. (GE 

with support from PW, AS) 

Fundamental property measurements 

12 - 36 

months 

Acquire velocity, attenuation, backscattered noise, 

and defect-echo data necessary to assess the 

effects of microstructural anisotropy and surface, 

curvature, etc., on forging inspections. (ISU with 

support from GE, PW, AS) 

18 months Provide velocity data for incorporation into the 

noise model. (ISU with support from GE, PW, 

AS) Complete techniques for curvature correction 

approaches. (All) 

24 months Provide surface curvature data for development of 

curvature correction factors. Provide data to 1.3.2 

for transducer design optimization. (ISU with 

support from GE, PW, AS) 

24 - 39 

months 

45 

months 

Validate noise models in cooperation with 3.1.2. 

(All) 

Report of the effects of anisotropy and 

surface curvature on inspection 

sensitivity for typical titanium forgings 

used in aircraft engines. 

45 months Initiate final report. (All) 

45 

months 

Techniques used to correct for geometry 

effects including curvature correction 

factors. 

54 months Complete final report. (All) 

60 

months 

Representative sample blocks of forging 

material or fundamental property 

measurements. 




Deliverables: 

Original 

Date 

Revised 

Date 


45 months Techniques to correct for geometry effects 

including curvature correction factors. 

54 months Report of effect of anisotropy and surface 

curvature on inspection sensitivity for typical 

titanium forgings used in aircraft engines. 

60 months Representative sample blocks of forging material 

or fundamental property measurements. 

Metrics: 

Assessments of the effects of microstructural anisotropy and surface curvature on inspection 

sensitivity for typical titanium forgings, supporting the needs of inspection development, POD 

estimation, and life management tasks. 

Comparisons of inspections using standard and optimized transducer designs, quantifying the 

improvement in detection sensitivity. 


Date 

Description 



Date 

Description 




Project 1: 

Task 1.3: 



Titanium Forging Inspection 


Titanium Forgings 

Team Members: 

AS: Prasana Karpur, Andy Kinney, Tim 

Duffy 

ISU: Tim Gray, Bruce Thompson, Frank 

Margetan, Ron Roberts 

GE: Dave Copley; Ed Nieters, Wei Li, Rich 

Klaassen, Mike Danyluk, Bob Gilmore, John 

Deaton 

PW: Jeff Umbach, Bob Goodwin, Andrei 

Degtyar 



Objectives: 

• To develop a high sensitivity ultrasonic inspection of titanium forgings utilizing a 1/128” (#½) FBH 

calibration target, digital C-scan image acquisition, and signal-to-noise rejection criteria target 

without significant cost increase. 

• To demonstrate the new technique in a production environment over an extended period to 

determine its feasibility (both cost and readiness) as a production inspection. 

Approach: 

Forging selection and preparation: Select one representative forging design from each of the OEMs 

for use throughout the duration of this subtask (both inspection development and demonstration). 

Selection criteria will include: 

• forging shapes that address generic concerns such as effects of curvature, surface condition, 

and part thickness 

• forging material and microstructure 

• forging cost 

• production volume and schedule 

Sensitivity and coverage maps will be developed for the selected forgings using model-based tools. 

CAD files will be provided to ISU by each of the OEMs for the selected forging geometries. Particular 

attention will be given to the effect of curved surfaces on inspection sensitivity relative to flat surface 

sensitivity. Calibration standards will be designed to cover the range of metal travel and curvatures 

found on the selected forgings. Plans include two sets of standards in order to support multiple 

member involvement. (Gray, Copley, Li, Nieters, Klassen, Umbach, Goodwin, Karpur) 

Transducer design models: Fixed focus and phased array transducer design models will be 

reevaluated in detail to determine reasons for discrepancies between predicted and measured 




subsurface focused transducer behavior observed during Phase I work. This reevaluation will focus 

initially on assessing how well the input parameters used for the models represent the physical 

behavior of the transducers. This effort will begin as part of Task 1.1 and 1.2 which will concentrate on 

fixed focus transducers. Two blocks (one for fixed-focus and one for phased array) suitable for the 

evaluation of subsurface focused transducers will be manufactured to provide experimental data with 

consideration given to samples available in 1.3.1. Based on this exercise, modifications will be made 

to model input parameters or to the model code to improve the prediction accuracy. Attention will also 

be paid to selection of transducer materials with consistent and measurable properties, for example 

the machining of lenses from solid material rather than using cast-in-place epoxy. Coordination with 

transducer and system vendors is expected with the objective of ensuring that results of this effort 

impact the performance characteristics of future products used in jet engine inspection. (Gray, 

Roberts, Copley, Li, Nieters, Danyluk, Umbach, Karpur) 

Surface finish effects: The effect of surface finish on inspectability will be determined. Surface finish 

requirements are anticipated to be more stringent at the higher sensitivity inspections necessary for 

forgings (compared to billet) and will be a focus of study in this subtask. Empirical and theoretical 

approaches will be used to assess the relationship between surface finish and inspectability. 

Empirical studies will be limited to 100 machining passes spread across five 13” diameter by 2” thick 

pancake samples. Results will be implemented in the UT modeling tools. (Roberts, Gray, Thompson, 

Margetan, Copley, Klaassen, Li, Gilmore, Umbach, Raulerson, Karpur) 

Transducer design and selection: The ultrasonic beam properties (frequency, depth-of-field, diameter, 

bandwidth, mode, etc.) required to produce an acceptable 1/128” FBH calibration (FBH @ 80%, Ti 

grain noise < 50%) will be defined. Fixed focus transducers for flat entry surfaces will be designed, 

manufactured, and evaluated using appropriate ETC test specimens as necessary. An assessment of 

the transducers (producing the above determined ultrasonic beam properties) necessary to inspect the 

three OEM forgings will be made. Any additional required transducers will be designed and 

manufactured. A commercial source for such transducers will be established. (Copley, Nieters, Li, 

Gilmore, Keller, Umbach, Karpur, Gray, Roberts) 

Productivity Improvement: It was shown in Phase I that inspection sensitivity improvements will, in 

general, increase the time required for the inspection. Fixed-focus transducer inspection approaches 

have the advantage of being expandable (in an economical fashion) to include the collection of data 

from multiple transducers simultaneously. This approach has the potential to offset the productivity 

losses which will likely occur from the increased inspection sensitivity required by this task. In order to 

meet the inspection time goals for this task, a study will be made of the OEM forgings to determine 

potential areas of productivity improvement. A maximum productivity approach will be defined and 

developed for evaluation in the laboratory demonstration. (Copley, Klaassen, Leach, Deaton, Nieters, 

Umbach, Goodwin, Karpur, Kinney) 

Fixed focus laboratory testbed: Laboratory testbed for the development and evaluation of the 

fixed-focus inspection approach for a 1/128” FBH calibration forging inspection with digital C-scan data 

acquisition and SNR based rejection criterion will be established. Additional transducers necessary to 

inspect the OEM forgings will be designed, manufactured and tested. Scan plans for the selected 

OEM forgings will be developed with model-based support. A limited number (1-2) of each of the 




selected forgings will be inspected per the scan plan. Performance of the fixed focus inspection 

approach for forging inspection will be documented. Alternative inspection technologies will be 

identified using the experience base of the four partners, as well as NTIAC. (Copley, Nieters, Keller, 

Klassen, Gilmore, Li, Umbach, Goodwin, Karpur, Gray, Roberts) 

Phased array inspection: An evaluation will be made of available phased array technology to 

determine which are potentially production-ready and capable. At this time, the digital focused array 

transducer system DFATS annular phased array and the R/D Tech 2D array are known as possible 

candidates. Development work on these approaches will be limited to building one sensor assembly 

for each approach if suitable sensors are not already available at the OEMs. Evaluation will be 

performed on appropriate ETC test specimens with both flat and curved sound entry surfaces. It is 

expected that phased array approaches will be necessary to arrive at the necessary sensitivity through 

curved surfaces. Arrangements will be made to accommodate full team participation for all of these 

evaluations. The results will be reviewed to identify a preferred alternative inspection technology. The 

review will consider inspection performance, equipment cost and complexity, operating speed, 

potential for productivity improvements, and other implementation factors. (Copley, Danyluk, Nieters, 

Li, Umbach, Raulerson, Goodwin, Karpur, Roberts) 

Phased array laboratory testbed: A laboratory testbed for the development and evaluation of the 

alternative inspection approach for a 1/128” FBH calibration forging inspection with digital C-scan data 

acquisition and SNR based rejection criterion will be established. Additional transducers necessary to 

inspect the OEM forgings will be designed, manufactured and tested. Scan plans for the selected 

OEM forgings will be developed. A limited number (1-2) of each of the selected forgings will be 

inspected per the scan plan. The full description of the testbed is not known at this time because of its 

dependence on the initial assessment. An amendment and appropriate request for funding will be 

prepared in consultation with the FAA when the details are completed. (Copley, Danyluk, Nieters, Li, 

Keller, Klassen, Umbach, Karpur, Roberts) 

Factory testbed, evaluation and demonstration: The laboratory results from the fixed-focus and 

alternative inspection method will be reviewed to identify a preferred configuration for factory 

demonstration and potential implementation. The review will consider inspection performance, 

equipment cost and complexity, operating speed, and other implementation factors. A hybrid system 

using fixed focus and an alternative inspection technology will be considered as part of this evaluation. 

The chosen configuration will be used to perform factory evaluation of 30 forgings at a production 

inspection facility. A production testbed with digital C-scan data acquisition will be established for the 

evaluation of the 1/128” FBH calibration forging inspection technique. (This may include the purchase 

of additional capital equipment if none is present at production inspection facility or available for loan 

from a consortium member.) Scan plans for the selected OEM forgings will be written by the 

respective OEM with ISU providing support using the inspectability model tools. Attention will be 

given to maximize productivity (to minimize any cycle time impact caused by the higher sensitivity) for 

the inspection during the production testbed design and scan plan development. Any additional 

transducers required to implement the scan plans will be designed using the transducer design models 

and built using commercial sources. A total of 30 forgings (10 from each OEM) will be inspected over 

the course of 10 months. Noise levels with respect to the calibration target, and actual inspection time 




in hours will be documented for each forging and provided to task 3.1.2. Any detections will be first 

reported to the responsible OEM. Up to six indications (from up to three separate forgings) which fail 

the proposed acceptance limits will be destructively evaluated to determine their cause. Funds to 

purchase these forgings are not included in the current proposal but will require an amendment at the 

time. The actual hours for the conventional production inspection of these forgings will be gathered 

and compared to the time of the 1/128” FBH inspection to establish a per part cost difference. 

Additional cost components will include items such as system cost, longevity of equipment, recurring 

equipment costs, and costs associated with false calls. An industry demonstration will be held to 

provide the results to the other OEMs and the forging industry. A final report summarizing the results 

of the technical effort and the final factory demonstration will be written in the required FAA format. 

(Copley, Danyluk, Keller, Leach, Klassen, Young, Umbach, Goodwin, Karpur, Kinney, Thompson) 


1998. 





Transducer Model Blocks – Material and machining quotes have been obtained for the transducer 

calibration blocks. These quotes indicated that it will be feasible to manufacture both the F/4 and F/8 

blocks from powder titanium material. Crucible Research Lab has been identified as the material 

source and Curtis Industries will fabricate the Flat Bottom Holes. 

Prior to placing the order for the powder met titanium blocks, a 2” cube of material will be fabricated by 

Crucible Research to evaluate microstructure and ultrasonic characteristics. The test block will be 

fabricated and evaluated during the next quarterly reporting period. 

Inspection & Calibration Plan – Each of the OEMs submitted the details of their “conventional” titanium 

forging ultrasonic inspection to Prasanna Karpur for inclusion in a composite table. Evaluation of this 

table by the team resulted in definition of a “baseline” forging inspection process which will be used to 

compare with the sensitivity, cost and productivity of the new zoned inspection process. The “baseline” 

process is very similar to the Pratt & Whitney process. It utilizes a 10 MHz transducer for the near 

zone (0.060” to 1.5” deep) and a 5 MHz transducer for the far zone (1” to 4” deep). Both will be 

calibrated to a #1 Flat Bottom Hole standard and Distance Amplitude Correction will be used to bring 

the signals to 80% of Full Screen Height. 

Forging Identification - The issue of access by foreign nationals to the forging information provided by 

the OEMs was resolved. ISU has a policy describing their approach to controlling this situation. The 

policy was reviewed by the OEMs and accepted. 

Following resolution of the foreign national issue, all three OEMs identified forgings for the Factory 

Evaluation portion of the subtask. Honeywell and Pratt & Whitney have provided drawings to ISU for 

generation of sensitivity and coverage maps. GE will submit their drawing to ISU in January. 





GE supply forging drawing to ISU for coverage and sensitivity evaluations 

Evaluate the 2” cube of powder titanium to determine acceptability as transducer model block material 

ISU initiate coverage and sensitivity analyses of OEM forgings 




Milestones: 

Original 

Date 

Revised 

Date 


General Issues 

3 months 7 months Finalize selection of OEM forging samples for 

study. CAD files will be provided to ISU for 

generation of sensitivity and coverage maps. (AS, 

GE, PW) 

3 months Complete design of transducer design model 

sample blocks. (GE with support of AS, ISU, PW) 

15 months Complete manufacture of transducer design model 

sample blocks. (GE) 

24 months Finalize and transition transducer design models 

to OEMs. (ISU) 

24 

months 

Transducer design models and software 

(both fixed-focus and phased array) 

transitioned to the OEMs. 

24 months Review fundamental property data from 1.3.1 for 

transducer design optimization. (ISU) 

29 months Complete model assessment of inspection 

sensitivity for OEM forgings including POD 

considerations in cooperation with 3.1.2. (ISU 

with support from AS, GE, PW) 

Fabrication of calibration standards 

All forgings identified. GE 

drawing to be delivered to ISU in 

Jan. 

complete 

15 months Complete calibration standard design. (All) 

24 months Complete manufacture of calibration standards. 

(GE) 

Calibration standards and transducers as 

needed. 

Surface finish studies 

36 months Generation of samples and collection of empirical 

data for surface finish studies. (GE) 

42 months Implementation of empirical results from surface 

finish results in UT model tools. (ISU) 

39 months Determine surface finish requirements for 1/128” 

FBH forging inspection. (All) 

42 months Review curvature correction approaches from 

1.3.1. (All) 

Titanium forging fixed-focus inspection 

development 

24 months Complete definition of transducer beam properties 

required for a 1/128” FBH calibration in Ti-6Al-4V. 

(ISU, GE, PW and AS) 

33 months Complete any needed new transducers. Establish 

commercial sources for transducers. (GE) 

Complete definition of maximum productivity fixed 

focus inspection approach. (GE with support from 

PW, AS, ISU) 




Original 

Date 

Revised 

Date 


39 months Establish fixed focus laboratory testbed. (GE) 

40 months Finalize scan plans for OEM forgings. (All) 

42 months Conduct laboratory inspection of high sensitivity 

zoned inspection on six OEM forgings. Provide 

data to 3.1.2 for model validation and POD 

prediction. (All) 

43 

months 

Laboratory demonstration of fixed focus 

high sensitivity forging inspection for flat 

surfaces. 

Titanium forging phased array inspection 

development 

36 months Complete evaluation of up to 3 candidate phased 

inspection techniques. (All) 

37 months Review results and select phased array inspection 

technique to pursue. (All) 

39 months Establish phased array inspection technique and 

laboratory testbed. (TBD) 

40 months Complete modified phased array inspection scan 

plans for OEM forgings. (All) 

42 months Conduct laboratory inspection of six OEM forgings 

using phased array approach as required. Provide 

data to 3.1.2 for model validation and POD 

prediction. (All) 

43 

months 

Laboratory demonstration of high 

sensitivity forging inspection utilizing an 

alternative technique for curved entry 

surface inspection. 

Factory Evaluation / Demonstration 

43 months Review results of laboratory inspections performed 

with fixed focus and the alternative technique. 

Define high sensitivity forging inspection for 

factory demonstration. (All) 

49 months Establish production testbed for high sensitivity 

forging inspection. (GE with support from PW and 

AS) 

49 months Finalize scan plans for OEM forgings. (All) 

57 months Complete production inspection for 30 forgings (10 

from each OEM). Provide data to 3.1.2 for model 

validation and POD prediction. (All) 

57 

months 

Factory demonstration of high sensitivity 

forging inspection including digital C-scan 

data acquisition performed on 30 

separate forgings. 

59 months Evaluate indication finds from production test, 

document results. Provide data to 3.1.2 for model 

validation and POD prediction. (All) 




Original 

Date 

60 

months 

Revised 

Date 




use by the Inspection System Capability 

Working Group and cost comparisons for 

the different inspection approaches. 

Deliverables: 

Original 

Date 

Revised 

Date 


24 months Transducer design models (both fixed-focus and 

phased array) transitioned to the OEMs. 

60 months Calibration standards and transducers as needed. 

40 months Laboratory demonstration of fixed focus high 

sensitivity forging inspection for flat surfaces. 

40 months Laboratory demonstration of high sensitivity 

forging inspection utilizing an alternative technique 

for curved entry surface inspection. 

57 months Factory demonstration of high sensitivity forging 

inspection including digital C-scan data acquisition 

performed on 30 separate forgings. 




comparisons for the different inspection 

approaches. 

Metrics: 

Demonstration of 1/128” (#½) FBH sensitivity inspection with digital C-scan data acquisition and 

SNR-based reject criterion for representative titanium forgings using zoned inspection approach with 

inspection speed comparable to current inspections. 


Date 

Description 



Date 

Description 




Task 2: 

Task 2.1: 


Inservice Inspection 


Rotating Components 

Development of UT Capability 

for Inservice Inspection 

Team Members: 

AE: Joe Chao, Prasanna Karpur, Andy 

Kinney 

ISU: Tim Gray, Bruce Thompson, Ron 

RobertsGE: Tony Mellors, Julia Collins, 

Walt Bantz 

PW: John Lively, Dave Raulerson, Rob 

Stephan, Jeff Umbach, Dave Bryson, Anne 

D’Orvilliers, Sheila Litschauer, 



Objectives: 

• To select an alternative coupling technology for performing UT inspection on inservice engine 

components. 

• To merge the selected UT technology with the ETC scanning technology, developed in Phase I, 

enabling the inspection of inservice engine components for subsurface defects as recommended 

by the lifing community. 

• To create a data processing platform in the ETC / DAS suitable for conducting either real-time or 

post test ultrasonic signal processing methodology developed in other subtasks. 

• To demonstrate a UT scanning system on two pertinent applications in multiple airline/overhaul 

shops and other venues. 

• To betasite test a UT scanning system at an airline/overhaul shop 

• To transfer sufficient data and information to one or more system developers to allow those 

developers to produce and support a commercial instrument which enjoys significant commercial 

demand. 

Approach: 

Implementation planning: During Phase I of the program, the inservice eddy current subtask focused 

on developing a set of eddy current tools to improve inspection of rotating titanium components. The 

goal of the Phase I effort was to develop tools with generic applicability to a wide range of engine 

makes and models. Arriving at digital data through controlled scanning which enabled post inspection 

analysis and more sensitive inspections attracted both airline partners and a commercial source for the 

Phase I tools. Two of the tools have direct applicability to the implementation of ultrasonic inspection: 

the portable scanner and the data acquisition system. Combined with a selected UT technology, a 

prototype inspection system will be built for demonstration and betasite testing in cooperation with the 

airlines. Commercialization focus will continue with system vendors using similar approaches to 

Phase I. The airlines and engine overhaul shops will be surveyed to determine their expectations for a 

final product as was done for the EC tools of Phase I. Critical features, critical locations, expected 




defect size, type, and morphology will be determined in cooperation with the lifing community. This 

input will be used to define the detectability requirements for UT and provided to the UT modeling task 

for use in inspectability model predictions. Expected usage requirements for the inspectability model 

will be defined by the OEMs for incorporation in tools to be delivered by ISU. (Smith, Stephan, 

Umbach, Bryson, D’Orvilliers, Duffy, Chao, Kinney, Karpur, Mellors, Traxler, Dziech, Gray) 

Determination of coupling method: During the first year of the program, a test matrix will be 

established by the technical team, candidate UT inspection techniques will be identified using alternate 

coupling methods, and comparisons will be made to traditional immersion UT. Various methods will 

be considered including traditional contact inspection and bubbler/squirter technology with 

consideration given to the availability of commercial UT coupling and scanning systems. Appropriate 

probe configurations (focal length, diameter, frequency) will be established with input from the 

modeling tools and through experimental studies in immersion UT. (Smith, Stephan, Umbach, Bryson, 

D’Orvilliers, Duffy, Chao, Kinney, Karpur, Mellors, Traxler, Dziech, Gray) 

Scanner and DAS modification: At this time, the leading candidate scanner for adaptation to UT 

inspection is the current ETC portable scanner and it is assumed that the ETC scanner will be pursued 

in the current proposed program. The capabilities of the ETC EC scanner will be verified during the 

effort under subtask 2.2.1 which will allow determination of any modifications to the prototype scanner 

for UT. UT requirements defined by the airlines and OEMs will be considered and a prototype scanner 

will be modified to account for the differences between scanning an eddy current probe and scanning 

a UT probe. Hardware and software modifications are expected to address the required changes to 

mechanical and electrical systems. The data acquisition system (DAS) will undergo some major 

modifications. The software developed in Phase I has received much praise during the extensive 

demonstrations and betasite tests, especially the scan plan generation capability. Continuing with the 

basic layout is of interest to the OEMs, their field support staff, and the airline customers to allow 

continuity and compatibility between EC and UT systems. Capabilities of the existing ETC eddy 

current portable scanner prototype systems will be considered with the goal to have a single portable 

scanner/data acquisition system which is truly generic to the inspection development process for 

inservice inspection of rotating components. This goal is motivated by requests from the airlines and 

OEM field support personnel. A single system results in singular training and operation experience 

with the resulting reduction in human factor effects. Extended capabilities also strengthen the required 

cost benefit analysis that airline inspection personnel must undergo to justify investment in new 

technology. 

Consideration will be given to the system level and user interface software. The current user interface 

software layout has been designed to accommodate additional tools such as UT instruments and 

techniques. System level software will be modified to provide seamless integration of motion and data 

acquisition using the existing Windows based approach. Other considerations in adapting the 

EC-DAS to UT inspection include the communication with the digitizer, the computer’s main 

processor, and the computer’s data bus. During development of the Phase I prototype system, 

processor chip technology was on a steep performance curve. The data requirements for UT signal 

processing may require a more powerful processor than the current prototype system. This, coupled 

with the availability of updated motion and data acquisition boards (namely PCI technology) and their 

compatibility with the processors, will likely necessitate the procurement of new computers for the 




prototypes. (Stephan, Lively, Raulerson, Litschauer, Duffy, Chao, Mellors, Young, Bantz, Traxler, 

Dziech) 

Specific issues relative to ultrasonics to be resolved early in the program include: 

• RF waveform collection and storage requirements: input as to expected data requirements (signal 

processing, data analysis, etc.) will be defined in cooperation with OEMs and airlines. 

• Analog outputs for external data recording: based on Phase I requests for EC data recording 

using external devices (such as strip charts), need will be solicited from potential users. 

• Motion synchronization pulse output for alternate means of data acquisition: This feature will allow 

the developer to use a legacy data acquisition system as an alternative to the DAS. Motion 

synchronization and encoder position information will be available. 

• Contour following requirements: more stringent requirements for surface/contour following, 

intimate contact of probe, and surface normality exist for UT compare to that required for EC. 

Compliance approaches used for EC with be reviewed for adaptability and other methods 

considered. 

Identification of applications: With guidance from RISC recommendations and resultant Advisory 

Circulars, as well as industry and OEM feedback, safety-critical UT applications will be identified. 

Three engine components, one from each OEM, will be identified and CAD files provided to ISU for 

inspectability predictions. Recommended inspection parameters will be generated using the 

inspectability models to support application demonstrations of the UT system, to shorten application 

development time, and more quickly optimize UT inspection parameters. Defects of interest include 

cracks (shear, refracted longitudinal inspection modes) and voids/hard alpha defects (longitudinal 

mode), with zoned inspections a potential requirement. (Smith, Stephan, Bryson, D’Orvilliers, Duffy, 

Kinney, Traxler, Dziech, Gray) 

Demonstration and betasite applications: The identified applications will be developed for 

demonstration at airline engine shops and are expected to be in critical areas such as disk and rotor 

features including bores, webs, and possibly rim and broach areas. Each OEM will have responsibility 

for application to their component with PW having primary responsibility for system readiness and GE 

having primary responsibility for UT deployment. Improvements will be made based on feedback from 

the demonstrations and a final system configuration developed. 

In addition to the two demonstrations, one betasite test will be conducted during the program to further 

refine the systems as requested by the end users. As in Phase I, ETC will participate in the annual 

ATA-NDT Forum to provide periodic updates to the airline industry and to obtain additional guidance 

on airline requirements. Details of the betasite applications will be defined in cooperation with life 

management personnel during the program. Data necessary for generation of POD curves will be 

identified in cooperation with task 3.1.2. (Stephan, Lively, Bryson, D’Orvilliers, Duffy, Mellors, Traxler, 

Dziech, Gray) 


1998. 





Efforts this quarter continued to focus on further defining Inservice UT inspection requirements, 

surfacing of portable scanner / DAS compatibility issues, identifying candidate UT coupling 

technologies, refining the UT coupling technology test matrix, and defining the UT modeling usage 

requirements. The following paragraphs cover the progress made in each of these areas. A schedule 

modification was required and is reported below. 

Inservice UT Inspection Requirements 

Specific UT inspection requirements are not necessarily required, though a general understanding of 

typical and potential applications is very important to help place boundaries on the development effort. 

To that end, PW was tasked with putting together a summary of the design constraints affecting this 

subtask. This document will help focus the near-term efforts and will eventually serve as a reference. 

The document will be issued next quarter. 

During other discussions of UT inspection requirements, the potential for a reduction in coverage 

efficiency was mentioned in trying to duplicate that of standard immersion transducers. It was 

generally agreed to by team members that multiple transducers (more than 2) would not be 

considered as a viable solution. GE indicated that typical inservice inspection procedures presently call 

for only one transducer, but utilize it in both shear and longitudinal modes with multiple scans. This is 

likely the scenario that will be implemented with the ETC portable UT scanning system. 

Portable Scanner / DAS Compatibility 

During a monthly conference call, a PW team member provided a summary of the UT instrument 

survey responses and reported on his assessment of their integration with the portable scanner data 

acquisition system (DAS). The UT instrument survey information will be used to determine which 

instruments are compatible with the ETC-2000 scanner and the priority of interfacing these 

instruments. The results of the survey include five vendors and eight models. The vendors and models 

are listed below: 

♦ IRT - UPI50 

♦ Staveley – Sonic 137 

♦ Panametrics – Epoch III 

♦ KB – USIP12, USIP20HR, USD15X 

♦ Sonix – DPR35G, DPR002 

Five of the models are completely compatible with the communications and data acquisition of the 

ETC-2000 scanner (Sonic 137, USIP20HR, DPR35G, DPR002, USD15X). One model (USIP12) is 

compatible with the data acquisition only. The remaining models do not provide the required inputs 

and output to make communications and data acquisition possible. 

In addition, a vendor survey has been completed of all the UT compatible, high frequency digitizer 

boards currently available. The high speed digitizer board will be used to acquire the RF data from the 

UT instruments. The minimum requirements considered were 200 MHz single channel acquisition, 

eight bit resolution and a PCI form factor. Three vendors were surveyed, Gage, Sonix and Signatec. At 




the current time Gage is the only vendor with a card meeting these requirements (Compuscope 8500). 

This card is also CE certified. Sonix produces a PCI bus based UT instrument but at the present time 

they only have ISA A/D cards. An updated product line is likely. Users of Signatec and Gage digitizers 

have expressed satisfaction with their products. Additional information regarding emerging new 

products will be collected before making a final decision. 

UT Coupling Technology Candidate Selection and Test Matrix 

Additional details of the UT coupling technology test matrix were defined this quarter through various 

sub-team discussions. Major areas of discussion included: 

♦ Pre-selection of best candidate coupling technologies for full testing 

♦ Coupling delivery hardware requirements 

♦ Transducer parameter definitions (model utilization) 

♦ Scanning issues 

♦ Specimen selection 

♦ Testing mode / measurement criteria 

After careful review of the alternate coupling technology comparison charts, two technologies were 

selected for full-scale testing. They are described as 1) a captured water column bubbler with a 

spherically focused beam and 2) a delay-line bubbler with an unfocused beam. 

Excluding the transducers, hardware for both of these coupling technologies is available at GE for 

initial testing. The basic components of each couplant system are available (in-house) and can be 

used with minimal modifications. The testing will begin upon selection and receipt of the ultrasonic 

transducers. Because the focus will initially be on transducer performance, a GE in-house immersion 

UT system will be used to test the candidate technologies. This approach assumes ideal coupling fluid 

delivery. It is anticipated that by June 2000, a means of testing the coupling delivery part of the system 

will have been acquired. At that time, the couplant delivery portion of the test matrix will be conducted. 

As mentioned above, the two candidate coupling systems will be scanned using GE in-house UT 

scanning facilities. After immersion baseline testing, the water level will be reduced and the coupling 

fixtures will be mounted to the scanning bridge. The test matrix presently contains a variety of 

scanning related tests to assess mechanical issues. Included are speed, scan density, and incident 

angle sensitivity measurements, as well as an assessment of coupling fluid problems. 

To assess performance metrics, both side drilled holes (SDH) and flat bottom holes (FBH) will be 

used. Near surface resolution will be determined by measuring the minimum resolvable SDH metal 

travel and the vertical separation of SDH leading edge and entry surface trailing edge. Spatial 

resolution will be determined by measuring the smallest detectable FBH over the target inspection 

range (0.020” to 2.0”). Area amplitude fidelity will be estimated by using a best fit to the theoretical 

area-amplitude linear function. 




UT Modeling Usage Requirements 

Krautkramer Branson (KB) and Iowa State University (ISU) have both begun a small series of 

modeling efforts aimed at establishing design limits toward potential ultrasonic transducer selection. 

The efforts with KB have been aligned toward establishing a range of transducers that can be obtained 

“off-the-shelf”, while the efforts with ISU have been directed toward establishing reflective sensitivity 

throughout the inspection region. Four transducers, 2 (5 MHz) and 2 (10 MHz) KB models have been 

identified for purchase. Further team discussion is required before the purchase will be made. 

Following the transducer selections, ISU will conduct trade-off studies, looking at a variety of test 

cases based on the inservice UT inspection requirements defined earlier. As an initial start to the 

trade-off studies, one model-based application was conducted this quarter. The goal was to specify 

probes that are smaller than the typical focused probes that are currently used in immersion scanning 

of forgings, but which yield the same sensitivity to defects. The model was used to compare the axial 

and transverse UT beam profiles from the smaller probes to those from the standard transducers so 

that quantitative comparisons could be made prior to probe purchase. 

Also this quarter, a survey was prepared and distributed to the OEMs to define model usage 

requirements. Primarily, the information sought in the survey was definition of the ranges of values of 

various model input parameters. These parameters included probe characteristics, material 

properties, and descriptions of defects. The survey also requested information concerning potential 

applications of the model that could favorably impact the development of the portable UT scanner. The 

results of the survey will be compiled and reported in the next quarter. 

Schedule Modification 

The 6-month milestone, as written, cannot be marked as complete. The coupling system referred to in 

the milestone, was defined as hardware that includes a transducer, a housing, a couplant delivery and 

recovery system, and all mounting fixtures. The “test demonstration unit” referred to in the 6-month 

milestone was then defined as the same thing, making it impossible to actually meet the milestone at 

this time. As a solution, the 6-month milestone was split into three separate items. The first and third 

items (see table below) will be marked as complete, while the second one will be moved out to 12 

months. This modification will not affect any other activities in this subtask. 


Further define critical features, locations, and defect morphology for typical inservice UT inspections 

and add to design constraints document 

Formalize immersion UT requirements based on current OEM commercial practices and procedures 

Document portable UT system design constraints (reference document) 

Gather information on commercially available portable scanner technology 

Complete inspection sensitivity trade-off studies using the UT models 

Select / acquire transducers based on modeling results 

Adapt in-house scanning fixtures to accommodate the two candidate UT coupling systems 

Name target UT instrument(s) for full integration into the DAS 




Discuss high speed digitizer acquisition rate and resolution 

Compile and distribute results of UT model usage survey; plan for incorporation of its results into the 

modeling capabilities 

Based on survey results and ongoing discussions, identify critical forging features and the locations 

and morphology of defects for model usage as applied to the development of the portable scanner 




Milestones: 

Original 

Date 

Revised 

Date 


3 months Identify alternate coupling technologies for 

evaluation and establish test matrix. (All) 

6 months Determine availability of commercial UT coupling 

systems and determine usage requirements for 

the UT modeling tools. (All) 

9 months Complete survey of commercially available 

scanner technology. Identify critical features, 

locations, and defect morphology for use in the 

modeling effort. (All) 

12 months Identify two engine components for demonstration 

to the airlines. Acquire CAD files and define 

inspection requirements for application 

development. (All) Acquire test demonstration unit 

(GE) 

15 months Complete evaluation of alternate coupling 

technologies (one technology to be selected for 

integration with the production EC scanner). (All) 

18 months Modify ETC EC Scanner (or acquire commercially 

available scanner) to accommodate UT 

inspection. (PW) 

20 

months 

Software and hardware revisions to the 

prototype portable scanner systems to 

enable both EC and UT inspections. 

24 months Demonstration of first UT application (P&W disk) 

27 months Identify betasite locations and initiate partnership 

with airline/overhaul facility. (All) 

33 months Complete assembly/testing of UT scanning 

system. (PW with support from GE, AS) 

39 months Demonstrate inspection capability through 

coordination with Subtask 3.1.2. (All) 

42 months Deliver UT scanning system to first airline 

overhaul facility for betasite testing. (All) 

48 months Complete betasite test. (All) 

52 months Refine UT scanning system based on betasite 

results. (All) 

60 months Report results. (All) 

60 

months 

Inspection data provided for analysis by 

Inspection Systems Capability Working 

Group. 

Complete 

Complete, one item moved to 12- 

month milestone. No adverse affect 

is expected. 

New item added 

Deliverables: 

Original 

Date 

Revised 

Date 


20 months Software and hardware revisions for prototype 

portable scanner systems to enable both EC and 

UT inspections. 

24 months UT application demonstrations using prototype 

portable scanner systems. 




Original 

Date 

Revised 

Date 


48 months One betasite test with the UT scanning system 

application. 

48 months Inspection data for analysis by Inspection Systems 

Capability Working Group. 

60 months Report of UT model deployment and validation 

efforts. 

Metrics: 

Reliable detection of #2FBH (or equivalent) at 4 ips scan speed (based on POD specimens, analysis 

to be performed by the Inspection Systems Capability Working Group). 

Detection of #2FBH (or equivalent) in critical area on typical engine components. 


Date 

Description 


July 15, 1999 Inservice Inspection Team Conference Call 

August, 18 

1999 

September 13, 

1999 

October 18, 

1999 

November 29, 

1999 

December 14, 

1999 

Inservice Inspection Team Conference Call 






Date 

Description 




Task 2: 

Task 2.1: 




Rotating Components 

Eddy Current Probe Evaluation 

and Implementation 

Team Members: 

AS: J. Chao, T. Duffy 

GE: J. Collins, T. Mellors, T. Patton, W. 

Bantz, S. Nath 

ISU: Ron Roberts 

PW: D. Raulerson. J. Lively, R. Stephan 



Objectives: 

• To evaluate and document the defect detection and performance characteristics of commercially 

available wide field eddy current probes to mechanical and material variations using common 

Ti-6Al-4V engine materials in a flat plate geometry. 

• To assess the defect detection capability of commercially available wide field eddy current probes 

on engine run hardware. 

• To evaluate and develop software methodologies to increase the signal-to-noise ratio of wide field 

eddy current signals on engine run hardware. 

• To produce configurations of widescan eddy current probes and inspection methods that can be 

implemented within a typical airline overhaul/service shop environment. 

• To demonstrate the capability to provide high throughput eddy current inspections on engine 

rotating components that contain generic critical inspection features. 

• To gather data to support Subtask 3.1.3 in providing validated POD on actual cracked specimens. 

Approach: 

The intent of this subtask is to utilize fundamental studies results to assess, substantiate, and 

document the defect detection capability and performance characteristics of commercial wide field 

eddy current probes on characterized flat plate samples of Ti-6Al-4V which will enable the 

implementation of wide field eddy current probe(s) on selected generic critical features of rotating 

engine parts such as: bores, faces, webs, flanges, slots, etc. 

Probe selection: Candidate wide field probes will be evaluated using the inspection criteria; oscillation 

drive current and frequency, defect detection capability, active scan area, single-pass scan coverage 

area, susceptibility to surface conditions and liftoff; and adaptability to other common inspection 

geometries. Each of the OEMs will be responsible for the evaluation of two (2 ea.) wide field probes 

using an experimental approach to be agreed upon by the technical team. To provide test uniformity, 

a common instrument platform, calibration standard, calibration process, and test procedure will be 

used for the experiments. Usage considerations, potential applications, and limitations for each wide 

field probe evaluated in this study will be identified. PW will be responsible for the preparation of 




samples from machined plates and engine run hardware. Samples will include EDM notches in flat 

plates, corners, and actual hardware, primarily in Ti-6Al-4V. (Amos, Raulerson, Bryson, D’Orvilliers, 

Duffy, Chao, Patton, Traxler, Mellors, Collins, Bantz, Nath) 

Probe characterization: The sources of unwanted eddy current signal noise will be identified. An 

attempt will be made to determine the root cause(s) of the signal noise due to surface microstructural 

and/or surface roughness changes in the material. This will be accomplished through correlation of 

the eddy current response(s) with surface characterization analyses of the Ti-6Al-4V material. This 

knowledge will be used for optimizing inspections with wide field probes and developing signal 

processing techniques to suppress unwanted responses. This work will involve: 

• Eddy current scans of flat plate specimens using absolute or differential wide field probes at 

frequencies less than or equal to 6 MHz. 

• Determination of the spatial correlation of the eddy current response to the variations of the 

material microstructure and surface roughness. 

• Examination of the magnitude and phase of the eddy current signals associated from material 

microstructure and investigation of appropriate phase angles which will maximize the S/N ratio. 

• Computation of a statistical distribution of the material “noise” signals for use in support of 

inservice inspection demonstrations. 

Data will be provided on actual cracked engine hardware and/or reliability specimens in support of 

Subtask 3.1.3. It is anticipated that modifications to the coil size, shape and shielding may be 

necessary to reduce the effects obtained from the microstructural evaluations before field 

implementation of the wide field coils on engine run hardware. Recommendations will be given to the 

vendors regarding any circumstances that indicate where an improvement in their product can be 

made. (Amos, Raulerson, Duffy, Chao, Patton, Traxler, Bantz, Nath, Filkins, Gigliotti) 

Evaluation on engine hardware: The candidate probes and techniques will be further evaluated and 

tested based on applicability to actual engine hardware. For this evaluation at least three high-profile 

rotating engine feature(s) will be selected for demonstration using one configuration for flat and/or near 

flat surfaces and two configurations for edge or corner geometries. Issues of accessibility, coverage, 

reliability, and throughput will be addressed. At least one engine component will be made available to 

the program from each OEM for this effort. PW is responsible for providing the FAA-ETC scanner to 

GE for the evaluation and development activities. Candidate wide field probes will be manufactured 

and modified based on results of the probe characterization studies. The applicable features of the 

engine components will be EDM notched. A comparison/correlation study will be performed using the 

candidate wide field probes on the applicable Ti-6Al-4V engine hardware to evaluate the potential 

inspectability of the wide field approach(es). Based on the outcome of this study, a final selection will 

be made to the preferred approach method. Instrument filtering, digital signal processing, and coil 

shielding techniques will be developed as applicable and necessary for S/N and edge detection 

enhancements based on previous evaluation results. Additional recommendations will be given to the 

vendors regarding any circumstances that indicate where an improvement in their product can be 

made. (Amos, Raulerson, Stephan, Lively, Duffy, Chao, Patton, Traxler, McKnight, Collins, Mellors) 




Field application: High profile, critical features of rotating engine parts will be selected by each of the 

OEMs including flats (GE), slots (AS), and fillets (PW). The candidate wide field eddy current probes 

will then be configured for implementation on applicable inspection platform(s) and performance 

verified. It is expected that the ETC portable scanner will be used as part of the inspection 

demonstration activities. An industry demonstration of the three inspection techniques will be held at 

an airline or service shop. To allow for accurate feedback, an open invitation to observe, will be 

extended to other airline industry representatives. Additional betasite testing is not planned as part of 

the current program but could be considered at a later date if the need is defined and funds are 

available. (Amos, Raulerson, Stephan, Lively, Duffy, Chao, Patton, Traxler, McKnight, Collins, 

Mellors) 


1998. 


Efforts this quarter focused on final procurement of wide field probes, continued development of the 

test matrix, fabrication of surface variation specimens, and definition of POD data requirements. 

Progress made in each of these areas is reported in the following paragraphs. A schedule modification 

was required and is reported below. 

Final Procurement of Wide Field Probes 

Honeywell has received wide field probe candidates from KB Engineering and NDT Engineering and 

PW has received the wide field probe candidate from UniWest. Physical characteristics have been 

forwarded to GE for compilation. 

A document was drafted to address supplier apprehension to openly participate in the ETC Wide Area 

Probe Sensitivity Characterization activity. Team members are currently reviewing the document 

which will be entitled “Ground Rules for Data Publication”. The final version will be sent to each of the 

probe manufacturers prior to reporting any test results. 

Also this quarter, an ISU representative discussed the ETC Wide Area Probe Sensitivity 

Characterization plans with a representative from Jentek Sensors, Inc. Though Jentek respectfully 

declined to participate in the ETC activity, they are pursuing an independent FAA relationship and plan 

to work on such items as blade slot fretting, edge crack detection, and POD measurements with 

Sandia National Laboratory. Coordination of these similar activities will be managed by the respective 

FAA representatives. 

Development of Test Matrix 

The first draft of the calibration section of the test matrix has been reviewed by team members. A 

draft of the full test matrix was delayed until after discussions with subtask 3.1.3 regarding 

requirements for POD data, and receipt of probe information from the other participants in this task.. 

Both of these items are finished, and a draft of the test matrix, based upon the probe calibration input, 

is scheduled to be distributed next quarter. 

The uniformity of the effective area of a wide field probe should be considered, as it has an effect on 

the complexity of the calibration procedure. If a wide field probe is proven to have a uniform effective 




area, then a single pass over a short notch can be used for calibration. The test matrix will include the 

appropriate tests to specifically define the “uniformity” of the WFP candidates. Other details of the test 

matrix are under development as well. 

Fabricate Surface Variation Specimens 

All of the surface variation specimens have been designed and are presently being fabricated. Ten flat 

plate specimen blanks have been machined and have been shipped to a supplier who will impart 

variations of shot peening intensities and media sizes. In addition, one full scale Web / Bore specimen 

is being machined to include various lathe turned finishes in the web features. This specimen will also 

contain a realistic bore and web/rim radius feature for future testing requirements. In addition to the 

machined specimens, several galled broach specimens will be cut from retired JT8D fan disks that 

have been returned to PW after being in service for full life. All of the surface variation specimens will 

receive edge and surface notches for determination of signal-to-noise ratio (SNR). 

For future testing, the team has decided to preserve several full-scale fan disks (field rejects from 

Honeywell) that have suspected broach flaws. Other available full-scale engine components include 

two disks at GE (Ti 6-4, D718) and one at Honeywell with a variety of EDM notches ranging from 

0.020” long to 0.100” long. 

Definition of POD and Noise Data Requirements 

A joint POD / Inservice Inspection team meeting was conducted this quarter to discuss data 

requirements and data collection strategies and to establish methods for communication between the 

two teams. The primary intent was to optimize usage of the EC data to be collected under the 

Inservice Inspection Tasks in support of POD task objectives such as noise characterization and 

model validation. As planned, all data for the Eddy Current POD task (3.1.3) will be collected while 

conducting planned technical efforts on three Inservice Inspection Sub-tasks. To help define them, a 

summary of the proposed data requirements (July 1998 Technical Proposal) was presented to the 

team for review. The proposal mentions POD data for wide field probes (2.1.2), POD data for the 

portable scanner with a conventional probe (2.2.1), and POD data for the unified high speed bolt hole 

EC method (2.2.2). 

On another topic, team members support the idea of "modular POD" and want to be sure that the 

noise data (material, surface condition, electronic) and signal data will be sufficiently useful for future 

POD calculations. Proposal references to data collection for noise assessments and EC model 

validation were not very specific. As a result, further discussion and planning will be necessary. 

Schedule Modification 

The 6-month milestone to complete acquisition and fabrication of all specimens, including machined 

and engine run hardware, cannot be marked as complete. The revised completion date is February 15, 

2000. This slip is not expected to affect any of the other milestones. 


Complete fabrication of surface variation specimens 




Compile list of all wide area probes on order from suppliers and OEMs and include operating 

characteristics 

Continue to develop the wide field probe test matrix 

Coordinate with EC POD task (3.1.3) regarding the type and amount of data to be collected. The 

coordination involves identifying the type of noise and model validation data that task 3.1.3 

representatives want to characterize and to translate the need to the type of data that needs to be 

collected under this sub-task. Two viable approaches to noise characterization are: 

♦ Group all noise factors as one category and try to encompass everything into a “noise” 

distribution. 

♦ Subdivide the various noise types such as surface finish, material and electrical and 

characterize each noise type separately. 

Initiate the data collection using the wide field probes on machined specimens with various surface 

finishes and peening requirements 




Milestones: 

Original Revised 

Date Date 


Fundamental Studies 

3 months Acquire commercially available wide field eddy 

current probes. Coordinate subtask support 

activities with Jentek Sensors, Inc. (ISU) (GE - 

Xactex, SECAP; AS - Staveley, NDT Engineering; 

PW - Uniwest, Widefield ECP) 

8 months Acquire, prepare, and EDM notch flat plate and 

corner samples from machined and engine run 

sources. (PW - machined and engine run 

Ti-6Al-4V) 

12 months Develop experimental plan to characterize probe 

sensitivity, characterize surface finish, and analyze 

noise variability. (All, GE - lead) 

18 months Evaluate and document the defect detection and 

performance characteristics of commercially 

available wide field eddy current probes to 

mechanical and material variations on common 

Ti-6Al-4V engine materials. (GE & AS - machined 

Ti-6Al-4V flats & corners; PW - galling, noisy 

Ti-6Al-4V) 

20 

months 

Eddy current signal and noise data taken 

from flat and near flat EDM notched, 

engine run hardware and plate samples 

for POD/PFA model estimates in 

cooperation with Subtask 3.1.3. 

24 months Evaluate and develop methodologies to increase 

the signal-to-noise ratio of wide field eddy current 

signals on engine run hardware. (All) 

26 

months 

Report of the detection and performance 

characteristics of wide field eddy current 

coils with respect to: material, surface 

conditions, probe type, signal-to-noise 

ratio, operating frequency, active scan 

area, and scan index. The report will 

document the advantages, limitations, 

cost, usage considerations, and software 

methodologies and techniques used to 

increase the signal-to-noise ratio of wide 

field eddy current signals for each 

commercially available wide field probe 

evaluated in this study. 

Validation and Implementation 

24 months Select high profile, generic critical features of 

Ti-6Al-4V rotating engine parts. (GE - flats; AS - 

slots; PW web fillet) 

33 months Design and manufacture prototype tooling and 

fixtures to use wide field probes on/with FAA-ETC 

Portable Scanner. (GE & AS - probe, holder, and 

support hardware, PW - FAA-ETC Portable 

Scanner integration) 

36 months Verify configuration of wide field eddy current 

Complete 

Pushed back 2 months to 

accommodate final machining. The 

slip will not adversely affect any 

other milestones. 




Original 

Date 

38 – 54 

months 

Revised 

Date 


probes and inspection methods. (All) 

60 months Report results. (All) 

54 

months 

60 

months 

Field demonstrate wide field eddy current 

inspection capability, on the three selected 

features, at one airline/service shop(s). 

Coordinate additional demonstrations with Task 

2.2.1 as appropriate. (All, PW - lead) 

Demonstration of wide field eddy current 

probe on engine applicable geometries 

utilizing the ETC portable scanner 

including participation by airline and 

overhaul personnel. 

Series of flat plate, and edge geometry 

samples made of machined and engine 

run Ti-6Al-4V materials to be included 

into the FAA-AANC database. The 

samples will contain EDM notches and 

possess varying surface conditions and 

microstructures. 

Deliverables: 

Original 

Date 

Revised 

Date 


20 months Eddy current signal and noise data taken from flat 

and near flat EDM notched, engine run hardware 

and plate samples for POD/PFA model estimates 

in cooperation with Subtask 3.1.3. 

26 months Report of the detection and performance 

characteristics of wide field eddy current coils with 

respect to: material, surface conditions, probe 

type, signal-to-noise ratio, operating frequency, 

active scan area, and scan index. The report will 

document the advantages, limitations, cost, usage 

considerations, and software methodologies and 

techniques used to increase the signal-to-noise 

ratio of wide field eddy current signals for each 

commercially available wide field probe evaluated 

in this study. 

54 months Demonstration of wide field eddy current probe on 

engine applicable geometries utilizing the ETC 

portable scanner including participation by airline 

and overhaul personnel. 

60 months Series of flat plate, and edge geometry samples 

made of machined and engine run Ti-6Al-4V 

materials to be included into the FAA-AANC 

database. The samples will contain EDM notches 

and possess varying surface conditions and 

microstructures. 




Metrics: 

The following metrics apply to applications using the wide field eddy current probe(s) on appropriate 

engine run hardware. 

Ti 6Al - 4 V 

Bores, faces and other near 

flat surfaces (engine run 

hardware) 

Corners, slots and other edge 

surfaces (engine run 

hardware) 

EDM notch size (mil) 30 x 15 x 3 40 x 20 x 3 

Signal-to-noise ratio (peak-to-peak) 3:1 3:1 

Scan speed (inch / sec) 3 1 

Scan area coverage per index (inch) 0.25 0.25 


Date 

Description 



August, 18 

1999 

September 13, 

1999 

October 18, 

1999 

November 29, 

1999 

December 14, 

1999 







Date 

Description 




Task 2: 

Task 2.2: 



Inspection Development 

Transitions to Airline 

Maintenance 

Application of ETC Tools in 

Overhaul Shops - EC Scanning 

Team Members: 

AS: Jim Hawkins, Jim Ohm, Tim Duffy, 

Joe Chao 


GE: Julia Collins, Tony Mellors, Shridhar 

Nath 

PW: Kevin Smith, Dave Bryson, Anne 

D’Orvilliers, Rob Stephan, Dave Raulerson, 

John Lively 



Objectives: 

• To demonstrate the reliability and reproducibility of the prototype portable scanner developed in 

Phase I including provision of necessary validation data for widespread implementation. 

• To gather sufficient data on industry applicable geometries for determination of POD in 

cooperation with 3.1.3. 

• To provide design and software modifications as necessary to ensure durability and flexibility while 

maintaining portability and cost effectiveness. 

• To fully transition the ETC inservice eddy current inspection tools to the airline industry through 

information exchange, cooperation with the production source, and industry exposure to the 

capabilities of the tools. 

Approach: 

During Phase I of the ETC program, the Inservice Eddy Current Inspection task focused on developing 

a set of tools to improve inspection on rotating titanium components. The tools, which included a 

portable scanner, a data acquisition system (DAS), and a low pressure rotor rotator (LPRR) were 

prototyped and tested on a variety of applications at the OEMs and in airline engine shops. During 

early betasite testing of the portable scanner and DAS, several hardware and software design 

modifications were identified and made to the prototype units. This process continued throughout the 

duration of Phase I. A total of three prototype portable scanner units were constructed and continue to 

be upgraded as new capability is defined based on airline and OEM experience with the hardware and 

software. Phase II efforts will continue to build on the experience and capability established in Phase 

I. 

Factory acceptance testing and POD: As mentioned above, a key aspect of the Phase II effort is in 

developing an extensive OEM experience base with the tools. During the first year of the program, 

each OEM will receive prototype systems to evaluate with an emphasis on performance and 

usefulness as part of acceptance testing. During this evaluation period, a common methodology for 




determining reliability and reproducibility of the systems will be identified and conducted. The 

determined reliability and reproducibility of the scanner will be compared to that of a fully automated 

EC scanning system. Early in the Phase II effort, the Probability of Detection (POD) for the portable 

scanner/DAS system will be determined. Data acquisition and analysis will be planned in conjunction 

with the POD subtask 3.1.3 to ensure that the data gathered can be used for model/methodology 

validation as well as provide sufficient information for POD analysis. The determined flaw size will 

serve as a metric for this subtask. (Smith, Bryson, D’Orvilliers, Stephan, Raulerson, Duffy, Chao, 

Traxler, Nath, McKnight, Bantz, Collins, Mellors) 

Service introduction: For full service introduction potential to be realized, attainment of a fully 

supported commercialization source will be required including identification of low cost manufacturing 

techniques, a marketing approach, and establishment of a global support base. The ETC Inservice 

Eddy Current Team will work closely with the commercialization source, including working closely with 

representatives from industry and the FAA on a viable approach to facilitate integration of the tools 

across the industry at large. One of the most fluid aspects of the Phase I systems is the software 

which includes system integration and a user interface. As new users begin to learn the capabilities of 

the scanning tools, the users become invaluable resources with feedback on how to make the system 

more useful. These ideas are implemented by continuous improvement of the software and followed 

by issuing revisions. It is anticipated that significant development to hardware and software will 

continue throughout the Phase II effort to incorporate the user defined needs. As these improvements 

are completed, all prototype units will be upgraded to ensure the best results during the service 

introduction. 

Efforts will include three new applications (one at each OEM). Applications will include a web, a bore, 

a broach slot, and at least one other disk feature such as the rim radius. These features are found on 

all models and makes of commercial jet engines and each have existing eddy current inspection 

requirements to some extent. 

Each OEM will identify an application and a betasite and develop the necessary tooling for conducting 

the test. The feedback from these applications will be addressed and any major issues will be 

resolved prior to the final service introduction effort. During the service introduction effort, existing 

inspections may be converted to OEM approved ETC portable scanner applications or new 

safety/durability applications will be addressed. A maximum of three service introduction applications 

are planned within the last two years, with the goal of obtaining full OEM certification as an equivalent 

approach to the existing technique. During this time, the effort will be directed at continued support of 

the tools while they are transitioned into the industry by providing application assistance, 

repair/modification of system components (including software), and training of new users. Results will 

be documented in the required FAA format. (Smith, Bryson, D’Orvilliers, Stephan, Lively, Raulerson, 

Duffy, Chao, Traxler, Dziech, Young, Filkins, Collins, Mellors) 


1998. 


Efforts this quarter focused on continuing to develop the appropriate acceptance criteria for the 12- 

month milestone, establishing a reference document based on the ETC-2000 system design review 




meeting, upgrading the prototype portable scanner systems, and modifying the operating and display 

software to accommodate suggestions and other feedback from ETC team members as well as ETC- 

2000 system users. Progress made in each of these areas is reported in the following paragraphs. No 

changes were made to the schedule. 

Develop acceptance criteria 

The 12-month milestone will be met utilizing the latest ETC-2000 production system. The Inservice 

Inspection Team will coordinate with UniWest on desired mechanical and electrical measurements 

which will be heavily based on the UniWest Acceptance Test Procedure. In addition to the mechanical 

and electrical tests, a generic POD study will be required. To prepare for this, all required endeffectors, 

probes, interface mounting H/W, generic calibration block, and a suitable specimen set will 

be acquired or fabricated as needed. Disk feature scanning will also be performed utilizing a typical 

engine part with EDM notches in various locations. Necessary arrangements will be made next quarter 

for a production ETC-2000 scanner to be available for these measurements at UniWest. 

In other discussions regarding acceptance testing, the Team decided that the production scanner’s EC 

signal path needs to be defined in terms of the loss/gain over the operating frequency range to ensure 

consistency across scanner systems. A specification was suggested to ensure proper SNR among 

deployed scanning systems. To address this issue, UniWest has added a specification and acceptance 

test for EC signal path. The revised UniWest “TechSpec” was distributed to the Team for review. 

ETC-2000 system design review 

The System Design Review (SDR) meeting was held at UniWest back in September 1999. Since then, 

several follow-up conference calls have occurred addressing many unresolved issues. Though most of 

the issues have been resolved, a few are still open and will need additional discussion to be brought to 

a close. The first meeting focused on a detailed review of the minutes from the SDR. Several main 

topics such as generic calibration, bolt hole inspection, thresholding, real-time processing, display 

routines, and contour following motion were briefly discussed. Several of these issues were resolved 

and for remaining issues, action items were assigned. To document the many issues that have been 

discussed and resolved, the Team decided to create an SDR summary document to be used as a 

reference. 

A second follow-up meeting included UniWest representatives and focused solely on the real-time 

display and processing approach. UniWest is using OpenGL to develop real-time display capability. 

The ETC team would like to assure that the basic display elements are all included and that these 

displays can be used in a post-inspection mode as well. Real-time processing is thought to be 

possible by enabling the use of plug-in routines. This capability will require an interface to handle 

signal processing and auto-classification routines. In practice, the scanner system should allow 

pseudo real-time processing / display capability so that indications found during the inspection can be 

displayed in near real-time. This enables the inspector to react to indications or scanning problems 

sooner, rather than wait until the entire inspection is complete. The scanner software should also 

provide an interface to user-defined algorithms which may enable automation of the inspection 

process. 




To ensure compatibility with existing software, the ETC will coordinate any system software 

modifications that will be necessary to accommodate this capability. It is anticipated that a basic 

thresholding module as well as additional more complex plug-in processing routines will be created by 

the ETC during planned service introduction and betasite activities. 

Additional conference calls will be necessary to address these previously surfaced issues: 

♦ IDL displays (interim solution, to be followed by OpenGL display suite) 

♦ Real-time display suite (OpenGL, need to define basic display elements and post-inspection 

capabilities) 

♦ Multi-axis / complex motion capability 

♦ Basic thresholding routine (and other plug-ins) 

♦ Controller replacement (CE cert. / PCI bus / complex motion compatible) 

♦ Portable UT inspection system conversion 

Upgrade the prototype portable scanner systems 

Work began this quarter in modifying the prototype portable scanner systems to be compatible with 

the production systems. The modifications will enable development of applications for service 

introductions and betasite testing. The following items are being addressed during this activity: 

♦ Select / procure CE certified / PCI compliant controller card 

♦ Rebuild all control boxes (3rd axis requires drive, power supply) 

♦ Procure new wiring harnesses 

♦ Consider emulating UniWest EC signal path (discussion required) 

♦ Procure / mount Mercotac rotary contacts (in addition to existing slip ring) 

♦ Add third motor wiring (R- or M- axis compatible) 

Modify the operating and display software 

A number of changes, additions and modifications have been made to the ETC code based on 

feedback from the ETC members and from betasite testing. This activity is required for the 

development of applications for service introductions and betasite testing. 

♦ Axis scaling, feedback gains and homing velocities have been moved to the AT6450.prg file to 

allow various motor and gearing configurations to be used without creating separate 

executables. This modification will allow the use of multiple R axes on the production systems 

and the different motors and gearing of the prototype scanners. 

♦ A default path dialogbox under the Options menu now allows default paths to be selected for 

scanplans, data and report templates. When opening existing scanplans the file open 

dialogbox will initially point to the default scanplan directory. When saving data, reports and 

threshold the file save dialogbox will initially point to the default data directory. When opening 

report templates the file open dialogbox will initially point to the default template directory. The 




default paths will make opening and closing files faster, easier and less error prone than 

before. 

♦ The Open and Close commands are no longer required. The individual scan routines will now 

automatically perform this task. This requires less work for the developer and allows 

integration of the scanning, processing and display routines. The “~etc.tmp” temporary data file 

is still available after each scan is completed and continues to exist until either the full scanplan 

is completed or until the next scan is begun. This temporary file can be used for data 

displaying or external processing purposes. At the end of each scan the user will use a file 

save dialogbox to select the desired data filename. This data filename is used as input to the 

Report and Threshold routines. Older scanplans are backward compatible. 

♦ The Display and ExProcess routines have been modified to allow double clicking of the 

scanplan line to bring up the file open dialogbox. 

♦ The ETC executable directory location limitation has been removed. This was accomplished by 

modifying the display routines and requiring the (*.sav) files to be in the same directory as the 

executable. The IDL executable and path can also be changed from the ETC.ini file, which will 

prevent having to create different ETC executables as IDL versions change. 

♦ The ArcBore and ArcWeb scanning routines now use inches instead of degrees for the C axis 

velocity and increment size and require a part diameter to be entered. Existing scanplans are 

backward compatible. If an old scanplan is modified the user is prompted to convert the C axis 

velocity and increment size to inches and add a diameter. The existing values will initially be 

set back to defaults. All new scanplans are created using inches for the C axis velocity and 

increment size. A text message has also been added to the dialogbox to show actual scan 

distance verses the travel distance entered. The actual scan distance is always less since data 

is only collected at constant velocity. An error message has also been added to warn the 

developer of creating a scan where constant velocity is never reached. 

♦ A new scan routine called PSSlot has been added to scan curvix, broaches and other slot type 

features. The scanning will be performed using the R axis with index capability in either the X 

or R axis and the C axis. The data collection will be the same method as the current Broach 

and Bolthole routines with data collected in both directions of the scan. 

♦ Report generation has been moved back to the Tools/ DAS menu as a scanplan command. 

This was done to allow better integration of the scanning process. The developer enters the 

Report command into a scanplan and chooses the desired template for use. A default template 

can be used or custom templates can be created by the developer. The user will be prompted 

to enter a filename in a file save dialogbox after filling in the required fields in the report. A 

suggested default report filename (*.txt) is generated based on the last data filename used 

during the scanplan, which can be accepted or changed. 

♦ The Thresholding routine has been modified to use the last data file collected or display a file 

open dialogbox if a scan routine has not been performed during the scanplan. The user will be 

prompted to enter a filename in file save dialogbox after the thresholding operation has been 

completed. A suggested default thresholding filename (*.txt) is generated based on the last 

data filename used during the scanplan, which can be accepted or changed. If a Report 




command has been previously issued and the default filenames accepted for both routines the 

thresholding information will be appended to the Report file. The thresholding routine has also 

been converted to use volts instead of counts for inputs and outputs. 

♦ Standard Windows printing capability has been added to allow scanplan to be printed from the 

ETC program. 

♦ A single IDL display in now being completed to allow displaying of all the currently available 

data types. 


Finalize the selection and procedures for testing the parameters defined in the acceptance criteria 

Select a specimen set for the generic portable scanner POD study 

Complete the definition of software interface format for the aforementioned plug-in algorithms 

The ETC application will be recompiled with the newer Microsoft C++ version 6.0 compiler 

The ETC dialogboxes will be modified to accept 52 inch diameter parts 

Evaluation of a replacement 4 axis CE certified advanced feature motion control board for the ETC 

prototype scanners will be conducted 

Generate a simple thresholding routine 

Make necessary arrangements for a production ETC2000 scanner to be available for acceptance and 

POD testing at UniWest 

Coordinate repeatability testing and noise assessment plans with the POD group 




Milestones: 

Original 

Date 

Revised 

Date 


12 months Complete factory acceptance testing, data 

gathering and analysis for reproducibility and 

repeatability determination. (All) 

16 months Complete inspection data gathering and provide 

data to 3.1.3. (All) 

16 

months 

Hardware and software upgrades made to 

the existing portable scanner systems. 

18 months Complete betasite test for undercut bores and 

webs. (AS with support from P&W) 

24 months Complete betasite test for attachment slots. 

(P&W with support from GE) 

36 months Complete betasite test for flanges/scallops. (GE 

with support from P&W) 

48 months Complete three inservice introductions utilizing 

overhaul shop personnel. (All) 

48 

months 

Three betasite test reports (one by each 

OEM, to be delivered at the end of each 

OEM’s betasite effort). Report 

documenting the three service 

introduction applications (Procedures, 

Tech Orders, etc.) 

54 months Initiate preparation of final report. (All) 

60 months Complete final report documenting betasite testing 

results and service introductions. (All) 

60 

months 

Deliverables: 

Report documenting the betasite testing 

results and service introductions 

On schedule for completion at 12 

months 

Original 

Date 

Revised 

Date 


Metrics: 

12 months Factory acceptance test plan (FATP) and final 

report on the reliability and repeatability of the 

portable scanner system, including POD estimates 

in cooperation with 3.1.3. 

16 months Hardware and software upgrades made to the 

existing portable scanner systems. 

48 months Three betasite test reports (one by each OEM). 

60 months Three service introduction applications 

(Procedures, Tech Orders, etc.). 

Crack detection capability of 0.030” X 0.015” in titanium bores and webs and 0.050” X 0.025” in 

titanium edges. 

Production portable scanner which is capable of validated inspection on bores, webs and attachment 

slots to target detectability levels. (EC Instrument not included). 

Successful implementation, installation and usage of at least one portable scanner for continued 

inservice inspection. 




Three betasite applications with constructive feedback from the overhaul shops. 

Approved alternate means of compliance for three service introductions (Initial release or alternate). 


Date 

Description 



August, 18 

1999 

September 13, 

1999 

October 18, 

1999 

November 29, 

1999 

December 14, 

1999 







Date 

Description 




Task 2: 

Task 2.2 





Maintenance 

High Speed Bolthole Eddy 

Current Scanning 

Team Members: 

AS: Tim Duffy, Jim Ohm 

ISU: Lisa Brasche 

GE: Tony Mellors, Shridhar Nath 

PW: Kevin Smith, Dave Raulerson, Dave 

Bryson, Rob Stephan 



Objectives: 

• To develop common fixtures to reduce inspection variables and arrive at a standardized inspection 

technique. 

• To measure the process capability. 

• To utilize this information to develop an industry best practice document. 

Approach: 

Evaluation of existing processes: Efforts will concentrate on process improvements for and 

standardization of high speed bolt hole scanning. A detailed evaluation of existing OEM inspection 

processes and needs will be conducted. Current equipment and tooling will be analyzed to provide a 

baseline of existing inspection processes and their limitations. The data will be analyzed for potential 

process improvements and identification of common tooling approaches. A survey of available 

commercial tooling will be included as part of the assessment and included in the baseline as possible. 

Examples of current systems are shown in the figure below. 

Development of common tooling: The efforts will then be focused on the detailed design and 

fabrication of common tooling with an emphasis placed on variability reduction and defect detectability 

improvements. An inspection demonstration will be conducted on a sample set of hardware from 

each of the industrial members for validation of process development. A comparison to the baseline 

data will be made. Working with task 3.1.3 an evaluation of the process POD will be conducted on 

existing bolt hole reliability specimens. 

Development of common process: A common inspection technique and best practices document will 

be developed. Currently AS4787, Eddy Current Inspection of Circular Holes in Nonferrous Metallic 

Aircraft Engine Hardware, serves as a standard for hole inspection. This document will be revised to 

reflect the results of the ETC effort. Recommendations for equipment improvements will be supplied 

to vendors and implications for further study will be provided to the FAA. 


1998. 





During this quarter, a matrix was developed showing details of OEM inservice bolt hole EC scanning 

techniques that are currently in practice at major airline and overhaul shops. The matrix is based on 

the information sheets that OEM members supplied. The nominal Industry scanning practice can be 

generally characterized as: 

♦ High speed probe rotator with 800-3000 allowable RPM range (1200-1500rpm, typical) 

♦ Non-fixtured application with manual feed & probe angle control (with some exceptions) 

♦ Probe body style: contact tip (diameter range) with Teflon tape 

♦ Probe element types: differential and reflective differential 

During a discussion of the nominal scanning characteristics, a number of major process variables 

were identified such as RPM, feed rate, and probe angle. Because the effect of these variables on 

system response is not known and would be difficult to predict (through modeling), a test matrix will be 

developed. Three specific specimen sets have been selected from the general list to be used for 

evaluating the variables. First, Honeywell has a set of Inco718 bolt hole specimens of a single 

diameter with a variety of notch sizes and locations which will be used for preliminary studies. Later, 

POD studies will be accomplished using either Ti 6-4 crack specimens (from GE) or Inco718 crack 

specimens (from PW-AF). 

Also derived from the OEM supplied information sheets were constraints on standard practices which 

included input on feature size ranges, calibration methods, rejection criteria, data archiving and 

applicable component materials. A few of the constraints are listed below: 

♦ Bolt Hole diameter range - 0.175 to 2.50 inches 

♦ Bolt Hole depth range - 0.125 to 4.00 inches 

♦ Titanium alloys 

♦ Nickel alloys 

As verified in the recently compiled OEM information, airlines and other engine shop requirements for 

bolt hole eddy current inspections are historically varied. This is primarily based on the fact that they 

are operating under OEM specific direction. During this program the ETC is chartered with providing 

an update to the airline industry’s “Committee K” on a bolt hole eddy current specification that unifies 

the OEMs and Airlines on an acceptable approach. Considering recent recommendations from other 

independent sources to this committee, a format was selected which models the specification written 

for eddy current inspection of flat plates. That document was distributed to team members for review. 


Define Process Variable Test Matrix & Equipment Requirements 

Identify Test Plan / Schedule for candidate high speed bolt hole EC method 




Milestones: 

Original 

Date 

0 –12 

months 

12 -30 

months 

30 

months 

30-36 

months 

36 –48 

months 

Revised 

Date 


Evaluate existing OEM techniques. (All) On schedule for completion at 12 

months 

Develop common tooling. (AS with support from 

GE, PW) 

Common tooling for reduced 

inspection variability. (All) 

Develop common inspection technique. (AS with 

support from GE, PW) 

Determine process capability. (AS with support 

from GE, PW) 

48 months Revise AS4787. (AS with support from GE, PW) 

48 months Issue Final Report. (AS with support from GE, 

PW) 

48 

months 

48 

months 

Revision of AS4787. 

Report of process capability and 

reliability. 

Deliverables: 

Original 

Date 

Revised 

Date 


30 months Common fixture for reduced inspection variability. 

48 months Common high speed bolt hole eddy current 

inspection technique through revision of AS4787. 

48 months Report of process capability and reliability. 

Metric: 

Common practices and tooling required to achieve a demonstrated 30 mil crack detectability and 4:1 

signal-to-noise in a common bolt hole geometry 


Date 

Description 



August, 18 

1999 

September 13, 

1999 

October 18, 

1999 

November 29, 

1999 





December 14, Inservice Inspection Team Conference Call 




Date 

1999 

Description 


Date 

Description 




Project 2: 

Task 2.2: 





Maintenance 

Engineering Studies of Cleaning 

and Drying Process in 

Preparation for FPI 

Team Members: 

AS: Tim Duffy, J Hawkins, R. Hogan 

ISU:Ron Roberts, Brian Larson 

GE: Terry Kessler, Charlie Loux 

PW: Anne D'Orvilliers, Brian MacCracken, 

Kevin Smith, Jeff Stevens, Joe Muraca, 

John Zavodjancik 


Program initiation date: To be determined. 

Objectives: 

• To establish a quantifiable measure of cleanliness including the minimum condition to allow 

effective inspection processing. 

• To establish the effect of local etching on detectability and provide guidance on best practices for 

removal of local surface damage from FOD and other surface anomalies. 

• To determine the effect of chemical cleaning, mechanical cleaning, and drying processes on the 

detectability of lcf cracks in titanium and nickel alloys that would be typical in field run hardware. 

• To update existing specifications to reflect the improved processes and provide best practices 

documents for use by the OEMs and airlines. 

Approach: 

The overall approach to the FPI studies is shown in the following flowchart with details provided in the 

text that follows. 

Literature and Industry survey: The effects of cleanliness, cleaning method, and drying method on 

penetrant inspectability will be evaluated. As a first step, a review of the literature related to FPI 

processes and cleaning and drying methods will be conducted. Literature related to cleaning 

processes as well as NDE processes will be reviewed. Existing CASR literature review data will serve 

as a starting point. 

A survey of current practices used by the OEMs, airlines, and third party maintenance shops will be 

conducted to determine the existing “state of the practice”. Potential partners will be identified for 

participation in the follow on studies on fielded hardware. A team meeting will be held to identify the 

cleaning methods and drying methods to be studied and the contaminants of concern. Other 

organizations not participating in ETC will be invited to attend the meeting and coordination with other 

relevant programs will be maintained. A design of experiments approach will be considered in order 

to optimize the use of the results. A set of 40 specimens, 20 titanium and 20 nickel will be generated 

by CASR staff. (D’Orvilliers, MacCracken, Smith, Muraca, Zavodjancik, Kessler, Loux, Duffy, Messih, 

Hawkins, Kinney, Roberts, Larson) 




Survey of common 

practices (industry) 

Survey of existing data 

(literature) 

Identify drying 

methods for study 

Identify cleaning 

methods for study 

Identify typical 

contaminants of 

concern 

Define and acquire 

crack samples for 

baseline studies 

Identify engine run 

hardware for use 

in cleanability 

studies 

Study to detemine 

"how clean is 

clean"; "how clean 

is needed" 

Use metrics 

established 

by 

MacCracken/ 

Kessler 

Assess methods 

at airline shops; 

compare against 

baseline sample 

Matrix of cleaning 

process effectivity 

vs contaminant 

Engineering study 

to determine effect 

of drying method 

on detectability 

(t and T) for 

oven drying 

flash drying and air 

drying 

Utilize lcf samples 

to extent possible; 

study on 

components 

required to 

address thermal 

mass issues 

Engineering study 

to determine effect 

of cleaning on 

detectability 

Potential variables: 

aqueous degreasers 

ultrasonic cleaners 

plastic media blast 

water jet blast 

solvent cleaners 

etching processes (local only) 

chemical cleaners 

vapor degreasers 

Utilize lcf crack samples to 

assess detectability; effect of 

cleaner on background, wetting 

characteristics, residual stress, 

etc. 

Matrix of drying 

process vs 

detectability 

Matrix of cleaning 

process vs 

detectability 

Develop best 

practices 

document and 

necessary spec 

changes 

Figure 2. Program Plan for “Engineering Studies of Cleaning and Drying Process in Preparation for 




Assessment of Cleanliness on Inspectability: A major concern for the inspector is the cleanliness of 

the part to be inspected and the impact that surface condition will have on detectability, with the 

question often being asked, “How clean is clean?” Some effort has been undertaken to provide 

guidance in this area in the most recent version of SAE 2647. An engineering study will be performed 

to assess the utility of these metrics through on-site evaluation at airline shops using field run 

hardware. lcf blocks will be used to establish a baseline and for comparison across test sites. A 

matrix will be generated that establishes the effectiveness of various cleaning methods in removing 

general classes of typical contaminants. It is expected that various operational conditions, types of 

cleaner equipment/systems, cleaner type, cleaner concentration, process parameters, and alloy types 

will be considered. Appropriate data will be gathered on the field systems used in the study such as 

chemical concentration of the cleaning solutions, temperature, etc to allow comparison between 

systems and to approved process parameters. Guidance on the effect of cleanliness on penetrant 

inspectability will be provided in the form of a cleanliness matrix that summarizes cleaning process 

effectivity for various contaminants. (D’Orvilliers, MacCracken, Smith, Muraca, Zavodjancik, Kessler, 

Loux, Duffy, Messih, Hawkins, Kinney,Larson) 

Assessment of the Effect of Cleaning Method on Inspectability: Given a definition of the required 

cleanliness from the effort above, an engineering study to arrive at the effect of cleaning methods on 

detectability will be performed using lcf blocks. Potential cleaning methods to be considered include 

• aqueous degreasers 

• ultrasonic cleaners 

• plastic media blast 

• water jet blast 

• solvent cleaners 

• etching processes (local only) 

• chemical cleaners for both Ti and Ni 

• vapor degreasers 

Local etching of FOD and other local anomalies to remove smeared metal and improve crack 

detectability is a common practice. An evaluation to define optimal local etching practices will be 

performed. Parameters within the global cleaning process which may need to be considered consist 

of degree of agitation, time spent in tanks, degree of concentration and post-clean, particulate size and 

content, pressure, etc. The effect of cleaning methods on background, wetting characteristics, 

residual stress, and crack detectability will be assessed. A matrix will be generated which establishes 

the detectability as a function of the selected cleaning processes and provided as a final product of the 

study. (D’Orvilliers, MacCracken, Smith, Muraca, Zavodjancik, Kessler, Loux, Duffy, Messih, Hawkins, 

Kinney, Brasche) 

Assessment of the Drying Method on Inspectability: Once the part is appropriately cleaned, it is 

essential that all fluids be removed from any rejectable defects such that penetrant solution can easily 

enter the flaw. Definition and adherence to appropriate drying times and temperatures is critical to the 

overall effectiveness of the FPI process. An engineering study will be performed to establish the 

optimal drying process parameters. Potential drying methods to be considered include air drying, oven 




drying, and flash drying. Initial studies will utilize lcf blocks with final recommendations to be based on 

actual engine hardware. A matrix that defines the effect of drying parameters on detectability will be 

generated. (D’Orvilliers, MacCracken, Smith, Muraca, Zavodjancik, Stephens, Kessler, Loux, Duffy, 

Messih, Hawkins, Kinney,Larson) 

Development of Best Practices Document: The final stage of the work will be generation of a best 

practices document that provides guidance to the OEMs and airlines and will allow for any necessary 

specification changes. An assessment will be made of the need for further work such as a formal 

POD study and recommendations provided. (D’Orvilliers, MacCracken, Smith, Kessler, Loux, Duffy, 

Messih, Hawkins, Kinney,Larson) 


1998. 


The team spent the reporting period in preparation for expanding the participation in this subtask to 

SNECMA and Allison/Rolls Royce. A letter formally requesting participation in the subtask and a 

proprietary information agreement protecting each of the participants was submitted to both SNECMA 

and Allison/Rolls Royce during this reporting period. Several telephone conversations were also 

conducted with the focal points from these organizations in order to answer technical and 

programmatic questions on the planned effort. Both organizations appear very eager to support the 

Engine Titanium Consortium in this subtask, however no formal acceptance of participation has been 

received to date from either organization. 


A meeting will be held in Phoenix, AZ on Feb. 7 th and 8 th to formally start the program. The meeting 

will be used to formally kick-off the effort by outlining tasks and deliverables committed for the first 

year of the program as well as to assign action items to the participants. Focus will be placed on 

compressing the current program schedule in order to expedite the program as much as possible in 

order to recover lost time on the program to date. A revised schedule will be reported upon the 

completion of the Phoenix meeting. 




Milestones: 

Original 

Date 

Revised 

Date 


2 months April, 2000 Complete literature survey. Complete industry 

survey of common practices used in cleaning and 

drying. (All) 

3 months May, 2000 Industry workshop to identify cleaning and drying 

methods, and typical contaminants of concern for 

study in the program. Establish experimental 

design for engineering studies. Define necessary 

crack samples and determine need for fabrication. 

(All) 

4 months June, 2000 Initiate “Effect of Cleanliness Study”. Establish 

partnerships with airlines to perform onsite 

evaluation of cleaning methods. (PW with support 

from GE, AS, ISU) 

6 months Aug. 2000 Initiate study to define optimal local etching 

practices. (All) 

10 months Dec. 2000 Complete “Effect of Cleanliness Study” and 

generate matrix. Complete local etching practices 

study and generate guidance document. Initiate 

Cleanability and Drying Studies. (All) 

22 months Dec. 2001 Complete Cleanability and Drying Studies and 

generate matrix. Initiate best practices document. 

(All) 

24 months Feb. 2002 Complete best practices document and provide 

recommendations for further study. (All) 

24 

months 

24 

months 

Deliverables: 

Original 

Date 

Feb. 

2002 

Feb. 

2002 

Revised 

Date 

Report documenting the Best Practices 

Document that provides guidance to the 

OEMs and airlines and will allow for any 

necessary specification changes. 

Report documenting recommendations for 

further work such as a formal POD study. 


12 months Feb. 2001 Guidance on an optimal process for local etching 

practices. 

24 months Feb. 2002 Specimen sets as required. 

24 months Feb. 2002 Matrices which define the cleaning effectivity vs. 

typical engine run hardware contaminants, 

detectability for various cleaning methods, and 

detectability for various drying methods. 

24 months Feb. 2002 Best Practices Document that provides guidance 

to the OEMs and airlines and will allow for any 

necessary specification changes. 

24 months Feb. 2002 Recommendations for further work such as a 

formal POD study. 

Technical program on-hold due to 

the request for increased 

participation 




Metrics: 

Improved cleaning and drying processes clearly defined for implementation by the industry as part of 

FPI used in inspection of critical rotating hardware. 


Date 

Description 

June 17, 1999 Technical Kick-off Meeting at West Palm Beach, FL 


Date 

Description 




Project 3: 

Task 3.1: 


Inspection Systems Capability 

Assessment and Validation 

POD Methodology Applications 

POD of Ultrasonic Inspection of 

Billets 

Team Members: 

AS: Prasanna. Karpur, Mike Gorelik 

ISU: Thomas Chiou, Bill Meeker, Bruce 

Thompson, Frank Margetan, Tim Gray, Ron 

Roberts, 

GE: Dick Burkel, Tim Keyes, Bob Gilmore, 

Derek Sturges, Bill Tucker 

PW: Jeff Umbach, Dave Raulerson, Kevin 

Smith, Phil Sherer, Rick Chenail, Bob 

Mattern, Chuck Annis, Taher Aljundi 



Objectives: 

• To enhance the ability to estimate the POD of naturally-occurring defects, such as hard-alpha 

inclusions in titanium billet, under a variety of inspection scenarios, through identification of a 

standard recommended approach for adjusting the parameters of the flaw response model to 

match the properties of natural-flaw populations. 

• To verify that the new POD methodology improves on the accuracy of existent techniques, 

provides more information such as PFA, and can be reliably applied to circumstances other than 

those of the actual experimental measurements as influenced by changing individual inspection 

parameters such scan index, transducer properties, etc. 

• To verify that the new POD methodology provides sensible predictions using more limited data 

than is possible with existent techniques. 

• To provide the OEM’s with tools to allow implementation of the new methodology in internal 

damage tolerance analyses by increasing the user-friendliness of methodology software and 

associated flaw and noise response models. 

• To provide the best available estimates of titanium billet POD by means of periodical updates to 

existing estimates based on new information such as new flaw data and extension of the POD 

estimates to a wider range of typical billet diameters. 

• To provide to the aircraft engine industry the first estimates and a capability for further estimating 

POD for ultrasonic inspection of nickel billet that is comparable to that provided by the new SNRbased 

POD methodology for titanium billet. 

• To provide the aircraft engine industry with meaningful assessments of the improvements in flaw 

detectability afforded by the ETC inspection developments. 




Approach: 

The proposed program consists of six major elements, which have been selected in response to the 

issues identified above. 

Method to Tune Flaw Response Model to the Behavior of Naturally Occurring Flaws: A standard 

approach for readjusting parameters of the ultrasonic response model to incorporate information about 

distributions of properties of naturally-occurring flaws will be developed. The starting point will be the 

general philosophy of the R e methodology, which uses experimental data from field finds to determine 

a distribution of responses of naturally occurring defects with respect to FBH’s producing the same 

response. However, the R e technique uses the physical assumption that the flaw size is small with 

respect to the ultrasonic beam width and is located near the beam axis, leading to the physical model 

that response is proportional to flaw area. This simple physical model clearly breaks down when the 

flaw is larger than the beam width, which is often the case in multizone inspections of hard-alpha 

inclusions, where the flaw may be elongated in the axial direction and the beam is tightly focused, or 

when the scan increment is too coarse with respect to the beam width in the focal zone. Complicated 

statistical procedures have been developed to compensate for these limitations in the ETC Phase I 

methodology. 

The advanced flaw response models that have been developed as a part of ETC-Phase I treats the 

case of flaws large with respect to the ultrasonic beam which may not be centered on the beam axis, 

thereby overcoming the deficiencies of the area response model used in R e . Procedures to “tune” the 

model are now needed, in a fashion analogous to that employed in the R e technique, but taking 

advantage of the much greater capabilities of the ISU flaw response models to treat realistic flaw 

geometries. During the first four months of the program, team members will jointly develop a 

recommended approach to this end. One candidate approach will be to modify the R e method by 

replacing the assumed FBH reflector with a cylindrical reflector viewed from the side. The response of 

such reflectors is readily treated by the new ISU models and it more closely mimics the overall shape 

of naturally occurring hard-alpha inclusions. (Chiou, Margetan, Meeker, Thompson, Sturges. Burkel, 

Smith, Umbach, Karpur) 

Assessment of success of the new POD/PFA methodology: The capability of the new methodology, 

incorporating ISU flaw response models for generating POD and PFA estimates, and for predicting the 

effects on POD and PFA of many individual inspection parameters, has already been established 

qualitatively and quantitatively, using synthetic flaws in test blocks of simple shape. The Random 

Defect Block will provide a similar test, but using the best available simulation of naturally-occurring 

hard-alpha flaws, in a block that closely resembles an actual titanium billet. The RDB has been built to 

a “stratified” statistical design, intended to ensure an adequate distribution of SHA properties to 

provide meaningful tests of the capability of both conventional and Multizone inspection systems, while 

allowing for sufficient randomization of the final choice of SHA parameters (such as length, diameter, 

percentage nitrogen, skew relative to the billet axis, and depth below the inspection surface) to avoid 

an inspector discerning any pattern to the design. Details of the design, currently known only to two 

GE metallurgists, will not be made known to other members of the ETC until after the acquisition of 

inspection data. Thereafter, these results (e.g., amplitude, SNR) will be compared with response 

ranges predicted from the ISU model to validate the adequacy of the flaw and noise response models 

to predict actual experimental data and hence, drive the methodology. A final stage in the validation 




process will be a test of the ability of the ISU model to predict the ultrasonic response from the 

complex-shaped natural flaws found during the CBS. The results will be analyzed by the team as a 

final validation of the Phase I methodology and any necessary modifications made. Efforts to assess 

the success of the new methodology will continue through its direct application in other Phase II work 

elements. (Brasche, Burkel, Chiou, Fulton, Karpur, Margetan, Meeker, Sturges, Thompson, Smith, 

Umbach, Chenail, Sherer, Mattern) 

Improvements and Transfer to the OEMs of the POD/PFA methodology and software: For the new 

methodology to have full impact on damage tolerant design and management of rotating components, 

it is necessary that the tools, i.e., software for implementing the methodology, the associated modules 

for predicting flaw and noise response, and materials characterization procedures to efficiently use 

them, be in a form readily used by the OEMs. These tools will be provided in Phase II. The 

methodology will be revised as needed based on results obtained in its application and software will 

be delivered to the OEMs incorporating those modifications. As dictated by the results of the RDB and 

CBS studies, any necessary refinements will be made in the flaw and noise response models. 

Included will be the development of numerical approximations to the predictions of the ultrasonic 

response models suitable for incorporation into the methodology. These may be thought of as 

approximations to the response surfaces which avoid executing the full flaw response calculation each 

time the methodology needs to examine a new case, thereby greatly speeding up the POD calculation 

process so that it will proceed at a rate which will be convenient for a user operating in an interactive 

mode. Selected improvements will also be made in the flaw and noise response models, supported 

by data generated in Fundamental Studies effort and that has the potential to significantly effect POD. 

Included will be the effects of microstructure on the ultrasonic beam profile, and hence, on the 

distributions of flaw responses; and the effects of tightly focusing the beam on the distribution of noise. 

In this latter case, it has been shown that, when the focal spot size approaches the dimensions of the 

macrostructure, the noise distribution is significantly modified. Models were developed in Phase I 

which described these effects, but a good means of determining the parameters that are inputs to the 

models, i.e., of characterizing the material, have yet to be developed. These procedures will be 

developed in Phase II. The laws governing the combinations of signal and noise distributions will be 

developed. Once known, these promise to greatly reduce the need for experimental measurements of 

flaw response to exercise the methodology and hence, should significantly increase its portability. 

Finally, the effects of variations in calibration response and uncertainties in the determination of flaw 

size on the accuracy of POD determination will be investigated, and the methodology will be modified 

as needed to accept these results. Effects of these software changes will be reviewed using JETQC 

and RDB data. Results of all of these software and procedural advances will be integrated and 

provided to the OEMs for their internal use. (Chiou, Gilmore, Keyes, Margetan, Meeker, Thompson, 

Tucker, Annis, Smith, Umbach) 

POD for titanium billet - existent/new data analysis, and use of the CBS: Additional information about 

the properties of flaws in titanium alloys will be collected and reviewed as it becomes available. 

Sources for this information include JETQC; the CBS, and the laboratory and pilot lot inspections 

planned as part of Subtask 1.2.1. Here, particular attention will be placed on the results for large 

diameter billets. This information will be reviewed and used to update POD estimates for ultrasonic 

inspection of titanium billet and to extend the POD estimates to cover billets up to 14″ diameter. 

Included will be a review of the revised inspection approaches for larger diameter billet, the 




development of any model modifications required to predict the flaw response for those approaches, 

validation of those models using calibration standards and chord blocks, and prediction of POD. 

These predictions will be compared to those of existent methodologies where the data is sufficient to 

allow existent methodologies to be used. 

Information from the responses of the CBS defects will be used in three ways. Ten of these defects 

will have undergone careful metallographic analysis in Phase I. As noted previously, this information 

will be a part of the detailed validation of the flaw response models. It will provide input to tuning the 

model for the response of naturally occurring flaws. Finally, methods will be sought and implemented 

to utilize the information in the remaining 50 flaws which were not the subject of destructive 

metallographic characterization. Here, the approach will be to seek a correlation between the C-scan 

image size (available for all 60 flaws) and actual defect size available for the ten which have been 

sectioned. If such a correlation is successful on these 10 defects, it will be used to estimate the size of 

all defects found in the contaminated heat. From this size estimate and the measured response, an 

enhanced data base for fine tuning the model for the response of naturally occurring flaws will be 

available. In addition, information about billet flaws gained from the related forging studies (i.e., from 

TRMD); and from direct comparison of Multizone and conventional ultrasonic inspection system 

performance, will be considered. Based on this information, integrated in the context of the new 

methodology, updated POD estimates will be made and provided to RISC and TRMD. 

New flaw detection data will be incorporated into revised estimates of titanium billet POD as they 

occur, and will provide a basis for revising the “default” POD estimates that have been supplied to the 

AIA Rotor Integrity Subcommittee (RISC). Comparison of predictions from the new methodology to 

those of existent POD methodologies will be made whenever sufficient data is available to support the 

application of the existent methodologies. (Burkel, Fulton, Karpur, Keyes, Meeker, Sturges, 

Thompson, Smith, Chenail, Sherer, Goodwin, Umbach) 

POD for nickel billet: The new methodology will be implemented on ultrasonic inspection of nickel 

billet analogous to that used for titanium alloys in Phase I. This will draw heavily on the modeling work 

of Phase I, and on results of fundamental studies and model developments planned for Phase II. 

Based on those fundamental studies, flaw response models will be developed for white spots and 

other defects from the critical flaw list. Flaw response data and noise data will be gathered, including 

any pertinent results from the pilot lot inspection in Subtask 1.1.2 as well as measurements on 

synthetic white spots in Subtask 1.1.1. These data will be used as the basis for initial estimates of 

nickel billet POD analogous to that employed for Ti-billet in Phase I, extended where possible by 

subsequent improvements in the methodology, as developed in Phase II. Measurements of calibration 

standards and chord blocks will be used for validation as appropriate. A study will be conducted of the 

effects of calibration response variability and determination of flaw size on the accuracy of POD 

predictions. Comparison of predictions from the new methodology to those of existent POD 

methodologies will be made when possible. (Burkel, Chiou, Gilmore, Karpur, Keyes, Margetan, 

Meeker, Sturges, Thompson, Tucker, Smith, Umbach, Mattern, Annis) 

Comparison of inspection systems - Use of the Random Defect Block: An assessment of the relative 

effectiveness of conventional and zoned inspection systems in use by billet suppliers will be 

concluded, based on the titanium RDB manufactured during Phase I. The RDB, which contains 

numerous SHA flaws, physically resembles a length of normal billet, and can be run through standard 




industrial inspection systems without special preparations, except that manual evaluation of results 

from Multizone systems will be required, instead of the standard automatic evaluation, because of the 

high density of defects in the RDB. The RDB will be used as a controlled sample to compare the 

number of SHA flaws detected by the alternative inspection systems. It is expected that acquisition of 

data from the RDB (using one conventional inspection system and one Multizone inspection system) 

will be completed during Phase I. These results will be analyzed in Phase II and expressed in terms of 

estimates of the POD (of SHA) for each inspection system. A small amount of additional data 

gathering (such as characterization of the transducers used for these inspections, to allow prediction of 

signal response) will also be required during Phase II. 

Results from this study will be coordinated with the Production Inspection Task, and will be integrated 

with studies of repeatability and/or reproducibility of conventional and Multizone inspection systems 

that were conducted during Phase I, and with new data from inspection of FBH blocks and the RDB 

that is planned as part of Subtask 1.2.1. (Chiou, Margetan, Meeker, Sturges, Thompson, Tucker, 

Umbach, Smith) 


1998. 


Random Defect Block: Significant effort has occurred in the random defect block project. Issues 

regarding “stealthy” defects in the RDB have dominated the discussions during this quarter. Using 

multizone systems at GE-QTC and Ladish, we have been able to detect only a small fraction of the 

total number of SHA defects embedded in the sample. During the October conference call Bob 

Gilmore provided an overview of his further inspection of the RDB at GECRD. He has inspected 41” 

of the 45” block. Gilmore showed images in which a large number of signals could be seen at 

positions corresponding to the seed locations. He reported that the billet was noisier in the deeper 

zones than his experience with titanium billet. Pat Howard indicated that the noise was on the high 

side but was acceptable. Gilmore also reported that “record-grooving” was evident on the surface of 

the billet and had resulted in excessive surface noise. Gilmore estimated that the surface wave 

obscured the first two inches of the billet. It was also indicated by GE-QTC staff that the current billet 

surface would not be acceptable for production billets. Therefore, the team arrived at the conclusion 

that any further work with the billet should include modification of the surface to typical production 

quality. The typical industry specification calls for a 63 microinch finish. Additional information was 

also provided in October relative to possible tilting of the seeds in the billet. This led to revisions to the 

technical plan for the RDB and delays in the proposal process. 

A summary of the RDB effort was prepared by Thompson for use in communicating about the 

program to the EIOB and TRMD. A copy is included at the end of this section of this report. A 

proposal was also prepared by the team in November. The need for destructive characterization has 

been emphasized by the team. It was reported that we will loose 3 to 4 seeds from either end of the 

billet. Seeds at each end of the billet are being considered for destructive characterization. 20%N 

seeds are located at 1.125" (1/8" dia. x 0.078" long, 0.4"deep) and at 42.9" (0.078 dia. x 0.078" long, 

3.92" deep). Other seeds would be lost as part of the sectioning process. The team will review data 

to be yet taken to determine selection. One seed will be sectioned in Phase I of the RDB study with an 




additional seed being considered as part of the Phase II program contingent on results of Phase I. 

Acoustic characterization prior to initiating the sectioning process is also seen as critical as additional 

cracking can occur as part of the sectioning process that is not present in the initial seed. 

Communication continues with TRMD through discussions with Gerry Leverant of Southwest 

Research Institute and Bruce Thompson. TRMD has included in their Phase II program issues related 

to “stealth defects” and there is interest in understanding how the RDB may contribute to that program. 

The summary document that follows this subtask report was provided to the TRMD team. 

Parameters of Hard Alpha-Diffusion Zone : ISU is working through calculations that require knowledge 

of the elastic constants as a function of N and other phase composition in Ti alloys. The basic issue 

that needs further consideration is the assumed absence of Al in the beta phase and V in the alpha 

stage, which has been recently studied by Gigliotti and B. P. Bewlay. Thompson and Chiou are using 

input from the paper in calculations for hard alpha. Thompson prepared a document for review by the 

CRD staff. 

CBS Reconstruction Activities: ISU has activities underway which includes an update to the 

reconstruction code to allow it to handle more generalized features and to automate the processing of 

micrographs. Included in the modification are efforts to address crack bifurcation and complexities of 

microstructural features. Efforts are underway to process the 8 CBS defects. The results of that work 

will be placed on the ftp site and the POD team notified for OEM review. 

Naturally occurring flaws – Thompson reported on recent discussions regarding naturally occurring 

flaws. The first milestone for task 3.1.1 will be accomplished by applying the agreed upon method to 

the GEAE3D database, which is reproduced below Several questions were posed to Sturges to 

provide information needed to guide the analysis. Included were the relationship between beam size 

and flaw dimensions (does the flaw extend outside the beam?) and the depth of the flaw in the original 

part (billet or forging as applicable). This information, not included in the database, is needed in order 

to model the expected response. Burkel has talked with Shamblin (GE staff member responsible for 

metallography) about availability of depth information. Burkel, Sturges and Gilmore will review internal 

data in consultation with Richard Chao of CRD. A subteam call was held on December 10 to discuss 

the databases available for naturally occurring flaws. The first milestone for task 3.1.1 will be 

accomplished by applying the agreed upon method to the GEAE3D database. A copy of that database 

is included for use by the POD team. 




BILLET/BAR 3D DATABASE PROPRIETARY TO THE ENGINE TITANIUM CONSORTIUM 

Sample Titanium Billet Melt Supplier Calibration Indication Noise Defect Core Size (inches) Diffusion Zone Size (inches) 

ID Alloy Diameter Type Code FBH # Amplitude Levels Axial X1 X2 Axial X1 X2 

1 Ti-64 13" 3X VAR A 3 70% 15%-30% 0.277 0.038 0.030 0.309 0.124 0.064 

3 Ti-64 13" 3X VAR A 3 100% 20%-40% 0.013 0.011 0.094 0.040 

7 Ti-64 12" 2X VAR A 3 100% 20%-45% 0.122 0.120 0.026 0.158 0.176 0.136 

32 Ti-64 12" 3X VAR C 3 100% 0.030 0.001 0.011 0.400 0.030 0.020 

18 Ti-6242 10" HM+VAR A 3 100% 10%-30% 0.635 0.025 0.045 0.701 0.042 0.062 

19 Ti-6242 10" HM+VAR A 3 NONE 10%-30% 0.012 0.003 0.001 

20 Ti-6242 10" HM+VAR A 3 NONE 10%-30% 0.058 0.018 0.010 

23 Ti-6242 10" HM+VAR A 3 80% 15%-25% 0.031 0.043 0.300 0.035 0.054 

24 Ti17 10" 3X VAR B 3 100% 40%-50% 0.101 0.025 0.130 0.493 0.074 0.197 

34 Ti-6242 10" 3X VAR C 3 80% 0.025 0.023 0.005 0.161 0.035 0.024 

35 Ti-6242 10" HM+VAR C 3 160% 35% 0.354 0.021 0.032 0.354 0.026 0.042 

21 Ti-64 9.85" HM+VAR A 3 NONE 10%-25% 0.014 0.055 0.085 0.180 0.070 0.085 

2 Ti-64 8" 2X VAR A 3 88% 15%-30% 0.235 0.028 0.012 0.235 0.044 0.022 

10 Ti-64 8" 2X VAR A 3 88% 15%-25% 0.176 0.028 0.016 0.180 0.048 0.046 

11 Ti-64 8" 2X VAR A 3 88% 15%-25% 0.180 0.052 0.024 

5 Ti-64 6" 2X VAR A 3 100% 10%-25% 0.247 0.038 0.030 0.284 0.104 0.108 

6 Ti-64 6" 2X VAR A 3 100% 10%-25% 0.571 0.016 0.010 0.711 0.030 0.039 

16 Ti-64 6" 2X VAR A 3 62% 15%-30% 0.484 0.020 0.024 0.484 0.026 0.040 

17 Ti-64 6" 2X VAR A 3 88% 15%-30% 0.182 0.013 0.021 0.234 0.019 0.025 

12 Ti-64 5" 2X VAR A 3 90% 20%-40% 0.068 0.010 0.015 0.138 0.016 0.020 

33 Ti-64 4.5" 3X VAR C 2 >100% 0.065 0.004 0.005 0.085 0.009 0.008 

4 Ti-64 4.25" 2X VAR A 2 >100% 15%-25% 0.190 0.021 0.019 0.602 0.044 0.040 

9 Ti-64 4.25" 2X VAR A 2 >100% 15%-30% 0.340 0.054 0.068 

13 Ti-64 4.25" 2X VAR A 2 >100% 10%-35% 0.152 0.016 0.020 0.215 0.024 0.041 

30 Ti-64 3.5" 3X VAR C 2 70% 20%-40% 0.190 0.003 0.001 0.190 0.011 0.006 

25 Ti-64 3" 3X VAR C 2 50% 20%-30% 0.220 0.018 0.012 0.255 0.020 0.045 

31 Ti-64 3" 3X VAR C 2 >100% 0.090 0.001 0.008 0.090 0.011 0.015 

36 Ti-811 1.25" HM+VAR D 2 100% 20%-25% 0.360 0.015 0.021 0.627 0.017 0.022 

NOTES: Data rows have been arranged in order of decreasing billet/bar diameter 

"Sample ID" refers to the original GEAE database; 8 rows lacking metallographic data have been deleted 

"Melt type": VAR - Vacuum Arc Remelt; HM - Hearth Melt 

"Supplier Code": Supplier names have been suppressed in accordance with GE/supplier agreements 

"Calibration FBH #" is the reference FBH diameter in 64ths of an inch. The response from the Calibration FBH was set to 80% FSH (Full Screen Height) 

"Indication Amplitude": %FSH. All inspections used FBH-DAC. "NONE" indicates a defect missed by UT 

"Noise Levels": the inspection procedure called for the accept/reject level to be set 10% above peak noise (which was probably the highest of the values shown) 

Defect Core and Diffusion Zone: typically, these defects are composed of a "core" or nugget of hard alpha surrounded by a "halo" or diffusion zone 

Core and Diffusion Zone dimensions X1 and X2 are believed to be mutually perpendicular, but are not necessarily radial and/or circumferential 

The CBS dataset will provide a second set of information for the POD of naturally occurring defects. 

Thompson is working with Chiou, Copley and in consultation with Brasche on the data that can be 

mined from the CBS indications that were not destructively analyzed in detail. The objective is to 

utilize as much of the ultrasonic data as possible, going beyond the 10 cut-ups. The primary technical 

question is how accurate is the “size” that has been inferred from the C-scan. To answer this 

question, these sizes will be compared to those determined by the successive sectioning. 

The following text reproduces the information regarding the random defect block status that was 

prepared by Thompson for the EIOB and the PMT. 




Random Defect Block: Plans and Status 

Initial Plans: 

The random defect block (RDB) experiment is intended to support the ETC’s efforts to establish, 

validate, and apply a methodology for determining the POD of the ultrasonic detection of internal, hardalpha 

inclusions in titanium billets. A summary of the initial program plan follows, based on a 

presentation made at the ETC Open Forum in November, 1997. 

Objective: 

1. To provide a vehicle for evaluating the success of the “S:N” based POD model under development 

• Validation of signal model 

• Validation of model for signal distributions, as influenced by noise 

2. In the process, to provide POD data for various inspection configurations 

• Comparison of conventional and multizone systems 

Background: 

• Need to validate the ISU model-based approach 

• Strong feeling that a “blind” test is required 

Approach: 

• Use POD methodology to predict performance 

• Compare these predictions to observations of various inspection systems 

Sample Configuration: 

• A 10-inch diameter billet in which synthetic, hard-alpha inclusions have been embedded by 

diffusion bonding techniques. 

Steps: 

1. Select inspection parameters 

2. Formulate test plan 

3. Select desirable overall detectability 

4. Stratified design (blind, based on theoretical guidance) 

• N different levels of response 

• M different flaws with similar response at each level 

• Random selection 

5. Inspect candidate material 

6. Build test block 

7. Reinspect block 




8. Conduct round-robin test 

9. Evaluate results 

Current status: 

Steps 1-4 have been completed. However, difficulties have been encountered at step 5 because 

many fewer defects were found than had been expected based on the sample design. Conceivable 

causes of this result have been identified as errors in 

• Model predictions 

• Sample fabrication 

• Ultrasonic measurements 

Each of these would have significant implications. If the models are inaccurate, they need to be 

corrected if they are to serve as a basis for POD determination. If the ultrasonic inspections do not 

have the capability that we assume them to have (i.e. that would be expected based on physical 

principles), then the community may be sub-optimally inspecting rotor grade material and/or taking 

credit for a greater capability than exists in practice. If the sample fabrication is inadequate, the 

consequences are not as severe, other than the loss of program resources. However, identifying the 

nature of any such inadequacies would provide information that has impact on future sample 

fabrication. 

A significant review of the random defect block program has been initiated to isolate the source of the 

problem. In the course of this study, additional experimental and modeling studies have been 

conducted for similar specimens prepared for the titanium rotating materials design (TRMD) program. 

These samples were similar to the RDB in that synthetic hard-alpha inclusions had been embedded in 

the samples by diffusion bonding techniques. The primary intent was to provide defects for forging 

studies. However, in the process, ultrasonic inspections were performed which provided the 

opportunity to compare the detectability of the defects in the TRMD samples, as expected on the basis 

of modeling, to those in the RDB experiment. A summary of the observations in the RDB and TRMD 

samples follows. 

For the RDB sample (10-inch diameter), results included the following. 

• The RDB contained 72 seeds, of which 52 were judged to be potentially detectable. 

• The 52 seeds were designed to have axial or near-axial orientations. 

• Of these, only 10 were found based on current accept-reject criteria. 

• These finds included 0 of 4 opportunities for 2.71% nitrogen seeds, 4 of 16 opportunities for 5.9% 

nitrogen seeds and 6 of 32 opportunities for 20% nitrogen seeds. 

• For those 5.9 % nitrogen seeds that were found, the signal strengths were close to the model 

predictions. 

• For those 20 % nitrogen seeds that were found, some had signal strengths that were close to the 

model predictions and others had signal strengths that were significantly less. 




• The responses of the 20% nitrogen seeds that were found were generally no greater than that of 

the 5.9% nitrogen seeds, contrary to the expectations based on the known effects of nitrogen on 

the ultrasonic velocity and therefore on the expected amplitudes. 

• There was a very high level of noise in the near surface zones that has been attributed to an 

improper preparation of the surface. It has been suggested that the surface roughness leads to 

the generation of surface waves which remove energy from the main beam and produce a large 

level of background noise. 

• Preliminary experiments performed by Gilmore at the GECRD suggest that many of these defects 

can be seen in C-scans obtained in his laboratory set-up. This observation could not be quantified 

at the level of effort available, but an estimate that 80% of the seeds are evident in C-scan results 

has been given. This suggests the possibility that the laboratory system has significantly better 

sensitivity than systems employed in production. However, this is not a definite conclusion, since 

the C-scans obtained at GEQTC and production sites have not been examined in the same way. 

The defects that were “found” in the production scans were identified on the basis of standard 

accept/reject criteria. 

For the TRMD sample (6-inch diameter), results included the following. 

• The TRMD samples contained 25 seeds, with some having axial, circumferential and radial 

orientations. 

• All seeds were detected (4 of 4 opportunities with 1.5% nitrogen seeds and 21 of 21 opportunities 

with 12% nitrogen seeds). 

• For those with 1.5% nitrogen, the signals were significantly greater that the model predictions. In 

fact, these signals were as great as those from seeds with 12 % nitrogen again in conflict with 

expectations based on the known effects of nitrogen on the ultrasonic velocity. It has been 

suggested, but not verified, that this might be do to local cracking. 

• For those seeds with 12% nitrogen, there was a reasonable agreement between the observed 

signals and the model predictions. 




Samples 

-3 dB Deviation Line 

+3 dB Deviation Line 

RDB 2.71%N 

RDB Noise Level at 33% 

RDB 5.9%N 

RDB 20%N 

TRMD 1.5%N 

TRMD 12%N 

0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 

The results of the RDB and TRMD experiments are presented in the attached figure. The abscissa is 

the predicted signal strength and the ordinate is the observed signal strength. Ideally, all signal 

strengths would fall on the solid line, passing through the origin and having 45 degrees slope. The 

dashed lines above and below that indicate acceptable agreement, given the target of 3dB accuracy in 

the models. The horizontal line, at an observed UT response of 0.33, indicates the noise threshold in 

the RDB (there is no corresponding record in the TRMD specimen). The points below this line indicate 

misses. No meaning should be assigned to their vertical positions since they were not detected. They 

are just plotted to indicate the levels of expected responses that were not detected. The fact that all 

but one of the detected 12% nitrogen (TRMD) and 5.9% nitrogen (RDB) seeds produced responses 

within the plus or minus 3 dB bounds is evidence in support of the accuracy of the model. The 

anomalous behavior of the 1.5% nitrogen seeds (TRMD) and the 20% nitrogen seeds (RDD), as noted 

above, is clearly evident and requires explanation if the model (or the input parameters provided to the 

model) are to be considered to be accurate.. 

Possible Future Directions: 

Predicted UT Response (% #2FBH) 

There are a number of important questions posed by these observations that are directly relevant to 

our understanding of POD. Examples include the following. 

• Why is it possible to detect all defects in the TRMD block but miss many in the RDB block? 

• Why do the 5.9 % and 12 % inclusions detected produce signals in agreement with the model 

while the 20 % seeds do not? 

• Is it true that the response of 20 % hard-alpha inclusions is not greater than that of 5.9 % 

inclusions? 

• Is there a significant difference in the sensitivity of the CRD laboratory system with respect to 

current field implementations? 




• Would those field implementations really miss uncracked, unvoided hard-alpha inclusions of the 

sizes and composition studied? 

• How important are the effects of surface finish? 

A program is being planned whose results would help answer these questions. Details are currently 

under discussion. As presently conceived, the program would involve modifying the surface of the 

billet to reduce the noise in the near surface zones, re-inspecting the billet with production or 

production-like systems to determine the degree to which this surface modification improves the 

inspection results, and destructively analyzing some of the defects to test the adequacy of the 

fabrication procedures. 

This document was prepared by Bruce Thompson on behalf of the ETC. He can be reached at 515- 

294-7864 or thompsonrb@cnde.iastate.edu. 


Complete several of the CBS reconstructions and review with the POD team. 

Submit the RDB proposal and initiate follow on effort upon approval from FAA. 

Utilize the available billet data to exercise the methodology on naturally occurring flaws, refining the 

methodology as needed. 

Provide a written description of the recommended method for tuning the flaw response model to match 

the behavior of natural defects. 




Milestones: 

Original 

Date 

Revised 

Date 


Approach to tune flaw response model to 

the behavior of naturally occurring flaws 

4 months March, 00 Provide a written description of the recommended 

method (GE, ISU) 

6 months A report defining a method for relating 

properties of naturally-occurring flaws to 

the parameters of the ISU model. 

Improvements and assessment of POD/PFA 

methodology 

Milestone will be completed in first 

quarter of 2000. 12 month 

deliverable of 3.1.2 is being 

accelerated and will serve as a 

common basis for 3.1.1, 3.1.2. 

General procedure for tuning flaw 

response model is included in the 

3.1.2 white-paper. 

Milestone will be completed in 

first quarter of 2000, as 

noted above. 

12 months Report results from applying RDB and CBS data 

to validate the ISU models developed in Phase I. 

(ISU, with support from AE, GE, PW) 

12 

months 

A report assessing success of the Phase I 

development of a new POD methodology. 

Ongoing Modify the modeling software if and when 

necessitated by experimental data. (ISU) 

30 

months 

30 

months 

48 

months 

Review and report on effects on POD of 

calibration response variability, and 

uncertainty in determining flaw size, 

conducted on Nickel only. (GE, with 

support from ISU) Provide OEMs with 

integrated software containing flaw 

response and noise models. (ISU) 

Report documenting the software and 

material characterization procedures with 

which the OEMs can implement the new 

methodology. 

Complete development and validation of 

models for the effects of microstructure 

on beam profiles and apparent 

attenuation. (ISU, PW with support from 

GE, AE) 

60 months Provide OEMs with final software and procedure 

packages. (ISU) 

POD for titanium billet - existent/new data 

analysis, and use of the CBS 

12 months Complete report of analysis of CBS data. (ISU, 

with support from AE, GE, PW) 

Ongoing Updated POD estimates for naturally occurring 

flaws in titanium alloys as new field-find data 

become available. (GE, ISU, with support from 

AE, ISU) 




Original 

Date 

Revised 

Date 


42 months Initiate POD assessment of revised inspection 

approaches for large diameter billet (10″ to 14″). 

(PW with support from ISU, GE) Characterize 

transducers to be used in inspection of large 

diameter billets. (Utilize results from 1.2.1) 

42 

months 

Report documenting the revised estimates 

of POD for larger diameter titanium billet 

51 months Predict response for large diameter billets. Use 

calibration standards, RDB, and chord blocks for 

validation as appropriate. (ISU with support from 

PW, GE) 

Provide POD estimate for larger diameter billet. ( 

ISU, with support from AE, GE, PW) Compare 

results with those from alternative POD 

methodologies. (GE, with support from ISU) 

51 

months 

Report documenting the estimates of POD 

and PFA for titanium billet based on use 

of the random defect block, CBS data, and 

data reported to JETQC, including 

comparison with POD results from 

existent methodologies. 

POD for nickel billet 

24 months Initiate nickel billet POD program utilizing results 

from Production Inspection Task. (ISU, with 

support from AE, GE, PW) 

30 months Characterize transducers to be used in inspection 

of nickel billets. (Utilize results from 1.1.2) 

58 months Predict response for nickel billets. Use calibration 

standards and chord blocks for validation as 

appropriate. (ISU with support from AE, GE, PW) 

60 months Provide report of POD estimates for nickel billet. 

(ISU with support from AE, GE, PW) 

60 

months 

Compare results with those from alternative POD 

methodologies. (GE, with support from ISU) 

Report documenting the POD and PFA 

estimates for nickel billet, including 

comparison with POD results from 

existent methodologies. 

Comparison of inspection systems - Use of 

the Random Defect Block 

(8/97 - 

Phase I 

(12/97 - 

Phase I) 

(4/98 - 

Phase I) 

(8/98 - 

Phase I) 

Program 

start 

Random defect block fabrication completed. 

ISU predictions of accuracy of model completed. 

Initiate ETC measurements using zoned and 

conventional inspection (on commercial systems. 

Complete measurements on RDB. (GE) 

6/15/99 Begin data analysis of ETC measurements on 

random defect block. (All) 

Completed. Effort initiated at 

program start in June 1999 




Original 

Date 

Revised 

Date 


6 months Incorporate interim results into provision of 

improved default POD curves to RISC and TRMD. 

(GE, PW, with support of AE) 

38 months Provide report comparing conventional and zoned 

inspection systems in use by billet suppliers, 

based on data from the Random Defect Block. 

(All) 

40 

months 

A report documenting the relative 

effectiveness of conventional and 

Multizone systems for the ultrasonic 

inspection of billet. 

Expect delay resulting from 

RDB issues. 

Deliverables: 

Original 

Date 

Revised 

Date 


6 months A report defining a method for relating properties 

of naturally-occurring flaws to the parameters of 

the ISU model. 

12 months A report assessing success of the Phase I 

development of a new POD methodology. 

30 months Software and material characterization procedures 

with which the OEMs can implement the new 

methodology. 

38 months A report documenting the relative effectiveness of 

conventional and Multizone systems for the 

ultrasonic inspection of billet. 

51 months Revised estimates of POD for larger diameter 

titanium billet (10″ to 14″). 

58 months POD and PFA estimates for nickel billet, including 

comparison with POD results from existent 

methodologies. 

Ongoing Estimates of POD and PFA for titanium billet 

based on use of the random defect block, CBS 

data, and data reported to JETQC, including 

comparison with POD results from existent 

methodologies. 

Milestone will be completed in first 

quarter of 2000, as noted above. 

Metrics: 

A procedure for incorporating the properties of naturally-occurring defects into a model-based POD 

methodology will have been defined in a formal report which becomes the basis for industrial practice, 

providing a consistent basis for future implementation of the POD methodology. 

The success of the new POD methodology developed in Phase I will be critically reviewed in terms of 

attainment of the original goals, using the following criteria: 

• POD results are more accurate that those of existing methodologies. They should be close (e.g., 

flaw size for a given probability within ±40%) to those from existing (R e and â-versus-a) methods 

when the requirements of those methods are satisfied and provide sensible predictions in cases in 

which the existing methods cannot produce answers. 




• PFA results are estimated as a function of threshold and these estimates are validated by 

independent experiments. 

• The method provides a means to predict the effect on POD and PFA of changing (as a minimum) 

transducer beam properties (diameter, focal length, water path, beam orientation); transducer 

frequency; scan index; flaw properties (location, dimensions, acoustic impedance, orientation 

relative to the sound beam); material properties (acoustic impedance, grain-boundary noise), with 

experimental validation that the response agrees with that predicted by the model, as a result of 

changing any one of these parameters, within accuracies typical of ultrasonic measurement, i.e., 

about ±3 dB (or ±40%). 

Modifications will be developed that will enhance the speed, simplicity of use, and range of 

applicability of the POD software developed in Phase I; the ease of operation will be demonstrated by 

successful transfer of the software to one or more OEMs. 

Estimates of the POD of hard-alpha defects in titanium billets will be extended to cover billet diameters 

up to 14″. Success of this enhanced capability for assessing the quality of one of the materials used in 

manufacture of aircraft engines will be indicated by incorporation of these estimates in life 

management calculations by the FAA, members of ETC and the Rotor Integrity Subcommittee of AIA. 

Estimates of the POD of hard-alpha defects in titanium billets, and of white spots in nickel billets, will 

be updated periodically. Success will be indicated by incorporation of these estimates in life 

management calculations by the FAA, members of ETC, and the Rotor Integrity Subcommittee of AIA. 

Improvements in detectability attainable through use of zoned ultrasonic inspection will be quantified 

and documented, permitting subsequent assessments by the OEMs of the effectiveness of such 

systems in improving the quality of titanium billet used for aircraft engine applications. 


Date 

June 14-15, 

1999 

Description 

Technical Kick-off Meeting in West Palm Beach, FL 

September 15, 

1999 

November 17, 

1999 

Workshop in Ames to discuss the random defect block and other 3.1.1 planning issues. 

Semi annual review with the FAA held in Kansas City. 


Date 

December 8, 

1999 

Description 

Thompson presented the paper “Determination of Probability of Detection of Internal Inclusions 

in Gas Turbine Engine Rotating Components” at the 4 th Annual FAA/Air Force Workshop on the 

Application of Probabilistic Methods to Gas Turbine Engines in Jacksonville, Florida 




Project 3: 

Task 3.1: 





POD of Ultrasonic Inspection of 

Titanium Forgings 

Team Members: 

AS: Prasanna. Karpur, Mike Gorelik 

GE: Dick Burkel, Bob Gilmore, Tim Keyes, 

Derek Sturges, Bill Tucker 

ISU: Thomas Chiou, Bill Meeker, Bruce 

Thompson, Ron Roberts 

PW: Jeff Umbach, Kevin Smith, Dave 

Raulerson, Bob Mattern, Taher Aljundi 



Objectives: 

• To extend the SNR-based methodology developed in Phase I to predict the POD of naturally 

occurring defects in titanium, sonic-shaped forgings for commonly used ultrasonic procedures and 

geometries. 

• To further extend the POD methodology to forgings of final shape, including the prediction of POD 

as a function of position within the part. 

• To provide the OEM’s with a set of tools which they can use to implement the new methodology in 

internal analysis of POD of forgings by increasing the user-friendliness of the methodology 

software and flaw and noise response models for forging conditions. Included are improvements 

in speed, accuracy, range of cases treated and reduction in the amount of experimental data 

required. 

• To improve the reliability of experimental methods for detecting flaws in sonic-shaped forgings and 

final-shaped, machined parts by developing and validating tools which allow evaluation of the likely 

effect on POD of proposed changes in inspections systems and procedures such as scan plans, 

transducer properties, gate widths, etc. 

• To verify that the new methodology produces POD results which are comparable with results from 

existent methodologies in cases when sufficient data is available that the existent methodologies 

can be successfully applied and which are consistent with reasonable expectations when such 

data is not available. 

• To provide the best available estimates of titanium forging POD to the aircraft engine industry, by 

means of periodically updating existing estimates based on new information, as it becomes 

available. This will include incorporating new flaw data, and extending the POD estimates to a 

wider range of typical forgings geometries through use of the ISU physical models. 

• To use this methodology to assess the improvements in POD afforded by the Production 

Inspection Task 1.3.2. 




Approach: 

This task will extend and apply the approach used in Phase I for billets to develop a method for 

estimating POD of naturally occurring flaws in forgings. The methodology developed in Phase I is 

based on detection theory concepts involving distributions of noise and of flaw response in the 

presence of noise. In this subtask, that methodology will be applied to the case of forgings, with a 

major extension being related to predicting the POD as a function of position within the forging. The 

proposed program consists of four major elements, which have been selected in response to the 

issues identified above. 

Application of the Methodology to Sonic-Shaped Forgings: Initial work in Phase II will use designed 

experiments to specify distributions of noise and signal response in existing blocks of forged material 

containing FBHs and/or SHAs. These experiments will involve review of available data gathered in 

Phase I followed by additional ultrasonic scanning of sample material with and without synthetic flaws 

as necessary. The initial focus will be on the effect of material anisotropy that results from flow lines 

created by the forging process on POD. The first step will be determination of the magnitude of 

anisotropy, which will be determined in subtask 1.3.1, Fundamental Studies. Given that information, 

the flaw response and noise models will be modified to take into account this anisotropy. Appropriate 

statistical distributions will then be developed, based on a combination of these models and 

experimental data to describe the distributions of signal and noise response for a simple forging 

geometry. Any further modifications needed to the methodology to take into account anisotropy will be 

made. 

When samples become available from Task 1.3, similar, but more extensive, experimental studies will 

be conducted on sonic-shaped forgings. These experiments will be conducted with samples 

containing flat bottom holes placed at some number n (to be determined later) positions in the sample. 

The positions will be chosen to provide a range of inspection geometries, surface curvatures, flaw 

depths, etc. Because of the symmetry of sonic-shaped samples, it will be possible to replicate these 

synthetic flaws systematically around the sample unit to allow a study of the variability of the 

responses of nominally identical flaws (providing important information needed to quantify sources of 

variability in signal response). Initial scanning, analysis, and modeling will be done on a 

representative sample of n/2 of the seeded flaw positions. The experimental data will be important for 

developing a methodology that will account for the strong effect that flaw location will have on POD 

with complicated geometries. The data will be analyzed to check and tune the deterministic 

signal-response model and to develop appropriate statistical models for the variability in the signal 

response measurements, the important components of the POD prediction model. The resulting POD 

prediction methodology will then be used to predict POD at the other n/2 positions, to validate the 

results. The data generated during these scans will also be used provide a database which will be 

used in the development of noise distributions, as influenced by surface curvature. 

Because a significant amount of the data will be generated in the above study, it should be possible to 

compare POD predictions from the new methodology with predictions of existing methods such as the 

ahat vs. a and the R e methods. Such comparisons will be made to provide an important check on the 

different aspects of the methodology over the required wide range of inspection conditions 

encountered in forgings. Efforts will be initiated to take into account the morphology of naturally 

occurring flaws in forgings. It is recognized that this morphology will be somewhat different from that 




in billets due to the deformations that occur in the forging process. Close contacts will be maintained 

with the TRMD program to obtain the necessary morphology information. (Meeker, Chiou, Margetan, 

Thompson, Gray, Sturges, Burkel, Smith, Raulerson, Umbach, Goodwin, Peters, Karpur) 

Development of the Capability to Make Predictions of the Local POD in Final Forging Shapes: 

Because of the complexity of the geometry of final part shape and of the effects of anisotropy 

associated with flow lines, the POD will depend strongly on position in final forging shapes. The new 

methodology is designed to take these effects into account, and this capability will be developed and 

applied. The essential steps that are required will be determination, on a point-by-point basis, the 

following: 

• Effect of forged material on the flaw response and noise distributions, building on the results of the 

sonic-shaped studies 

• Effect of surface curvature and other geometrical parameters on the beam shape and there by on 

the flaw response and noise distributions 

In parallel, an implementation plan for including these point-by-point variations in the methodology will 

be developed, so that the result can be efficiently integrated with the life prediction code, DARWIN. 

Experimental validation will then be undertaken. The ultrasonic response model will be used to predict 

signal response from flaws which are insonified through representative surface geometries using the 

samples being developed in Task 1.3.1. Samples will be designed in cooperation with 1.3.1 to 

evaluate the full range of surface curvatures typical in final and sonic shape forgings. Consideration 

will also be given to evaluation beyond typical curvatures to determine the limits of the model 

applicability. The flaw response model will be verified by scanning these specimens and comparing 

these observations to the model predictions. Checks on the resulting POD predictions will be made 

for certain testing situations for which POD curves have been estimated by other means (e.g., the ahat 

vs. a and the R e methods). Upon completion of these tests, an updated version of the methodology 

will be prepared. (Meeker, Chiou, Margetan, Thompson, Gray, Sturges, Burkel, Smith, Raulerson, 

Umbach, Goodwin, Annis, Peters, Karpur) 

Improvements/Transfer of the POD/PFA Methodology Software to OEMs: For the new methodology to 

have full impact on damage tolerant design and management of rotating components of aircraft 

engines, it is necessary that the tools, i.e., software for implementing the methodology, the associated 

modules for predicting flaw and noise response as influenced by anisotropy and geometry, and 

materials characterization procedures to efficiently use them, be in a form that can be readily used by 

the OEMs. These tools will be developed, incorporating the results of the previously described major 

work elements. Included will be the methodology software, flaw and noise response modeling 

modules (as influenced by anisotropy and part geometry), and characterization procedures to provide 

the necessary inputs. As in 3.1.1, numerical approximations to the predictions of the ultrasonic 

response models will be developed which are suitable for being called by the methodology to speed 

the calculation process to a rate which will be convenient for a user operating in an interactive mode. 

Also building on the experiences gained in the Task 3.1.1, the flaw response models and noise models 

will be designed to incorporate the effects of microstructure on beam profile, and hence, on the 

distribution of flaw response, the effects of tight focusing with respect to the scale of the microstructure 

on the form of the signal and noise distributions, and the rules required to determine the distribution of 




signal-in-the-presence-of-noise from the noise distribution and the flaw free noise response. All of 

these will be considered as influenced by the presence of anisotropy and beam modification by the 

part geometry. Results of these software and procedural advances will be integrated and provided to 

the OEMs for their internal use. These uses are anticipated to include life management calculations, 

such as consideration of the likely effects on POD of proposed changes in inspection systems and 

procedures such as scan plans, transducer properties, gate widths, etc. (Meeker, Chiou, Thompson, 

Gray, Sturges, Burkel, Smith, Umbach, Chao, Karpur) 

POD for Titanium Forgings: Efforts to acquire naturally occurring hard alpha inclusion data will be 

continuously made. Possible sources include field and manufacturing finds, the utility of which will 

depend on the degree to which appropriate procedures are utilized to fully characterize the 3-D shapes 

of these finds. Information gained during the forging studies of the TRMD program will also be used. 

This information will be used, as appropriate, to provide POD estimates. 

The methodology will be used to evaluate the improvements in POD afforded by developments of the 

Production Inspection Task 1.3.2. (Thompson, Burkel, Sturges, Smith, Brasche) 


1998. 


White paper activities: Efforts to complete the first milestone for 3.1.2 are well underway with Bill 

Meeker coordinating the activity. Several conference calls took place during this quarter to define the 

requirements and the approach to the development of the new POD methodology. Bill Meeker 

outlined two approaches in a white paper distributed to the OEMs on 1/5/2000. The following schedule 

was established to generate the revised draft of the white paper. 

Schedule: 

December 10 - Input to Bill Meeker from other contributors 

December 15 – Questions from Bill to other contributors 

January 4 – Next draft of white paper distributed to team 

January 15 – Discussion of white paper at monthly conference call 

The outline for the white paper and contributing parties are as follows: 

1. Description of method of determining noise distribution 

a. From data (Meeker) 

b. From FOM (Margetan) 

2. Description of ISU physical model for UT (Thompson) 

3. POD Methodology 

a. Based on ISU model (Meeker) 

i. Empirical noise 

ii. 

Modeled noise 




. Based on Tucker model (Tucker) - clear, but brief, written description of the method will be 

provided by Bill Tucker. 

i. TBD by Tucker 

ii. 

TBD by Tucker 

4. Modularity/portability (Meeker, Smith) Smith will provide OEM views on needs for modularity, 

corresponding to diagram presented at Ames workshop. 

5. Needed Experimental Data (Meeker, Chiou, Margetan) – team to give consideration to changing 

title of this section. 

a. FBH blocks 

b. SHA blocks 

c. CBS 

d. Fundamental studies blocks from Phase II 

e. “Sonic shaped” specimen 

• curvature 

• anisotropy 

• replication of nominally similar synthetic flaws (FBH or SHA) 

f. “Noise” data 

6. Other OEM issues (Meeker, Smith, Umbach, Sturges, Karpur) - Sturges and Smith to provide 

input on 6a. 

a. Location-specific POD 

b. Model “verification” 

c. Quantification of uncertainty 

i. model 

ii. 

statistical 

d. Software (Thompson, Brasche, Meeker) 

• Inputs and interfaces with ISU UT model 

Several technical points are being addressed as summarized here: 

♦ A key element of the methodology is the availability of appropriate noise distribution data. Four 

datasets were identified for use in the noise distribution analysis: 

1. Ti-17 data utilized in Howard, Burkel, Gilmore study 

2. ISU data gathered by Chiou on blocks (with FBH and SHA) as part of Phase I 

3. Yalda/Margetan data gathered as part of fundamental studies effort from Phase I 




4. 8 forging and 24 billet datasets used in Tucker/Keys studies. Filenames for this dataset are 

being gathered and a release sought so that the data can be provided to ISU for study. 

• Meeker indicated that he planned to try to incorporate an example using real data to illustrate the 

methodology. The data gathered on the FBH and SHA samples in Phase I was identified as 

candidates. Meeker also wishes to analyze some of the noise data that was studied by GE in 

Phase I. Sturges accepted the assignment of seeking the release of that data from GEAE. 

• Tucker amplified on comments that he had made in the September workshop regarding the form 

of the noise distribution. The essential idea is that Tucker proposes a “particle distribution” based 

model as an alternative to the “communication theory” model that has been proposed by ISU. His 

proposal was motivated by the analysis of noise distribution data that was conducted in Phase I by 

Tucker and Keyes. In that work, it was assumed that the distribution of gated peak-to-peak noise 

could be described by the maximum of M independent samples of an underlying distribution, with 

the value of M and the parameters of the underlying distribution being determined by maximum 

likelihood techniques. Five underlying distributions were considered, the Rayleigh, Weibull, K, 

lognormal and LEV. Analysis of the degree of fit to the data indicated that best performance was 

obtained when the underlying distribution was lognormal or K. The strength of the K-distribution 

had been expected on the basis of underlying “communication theory” arguments by Margetan, 

Yalda and Thompson. That of the lognormal did not have a similar physical motivation at the time 

of the analysis. Tucker’s discussion of a “particle distribution” model represent a first attempt to 

describe the success of the lognormal distribution. 

The availability of “field find” data for forgings, analogous to the GEAE 3D database for billets (see 

3.1.1) was discussed. It was agreed that Sturges, Degtyar, and Duffy would seek such data from their 

respective organizations. Attributes of an appropriate dataset include the availability of unsaturated 

signal strengths, 3D size information for the flaw, the flaw position, and details of the inspection 

(thresholds; calibration procedures; transducer frequency, size and focal properties.) 


Third generation of the white paper will be prepared, including discussion of noise distributions, 

analysis of available noise, and natural flaw data. This will require release of noise data to ISU. 




Milestones: 


Date Date 


Application of the Methodology to 

Sonic-Shaped Forgings: 

18 months Complete scanning and analysis of blocks of 

forged material with FBH and SHA flaws. (ISU 

with support of AS) 

22 months Investigate the application of Phase I methodology 

to the scan data on forged material with FBH and 

SHA flaws. (ISU) 

24 months Initiate generalization of the POD methodology to 

apply to sonic-shaped forgings. (ISU with support 

from GE) 

27 months Define experimental plan for use of FBH and SHA 

sonic-shaped forged samples available from 

TRMD and Phase II Production Inspection Task. 

(All) 

27 

months 

Report documenting a method for 

predicting POD for sonic-shaped forged 

parts. 

30 months Acquire data from available FBH and SHA 

sonic-shaped forged samples to generate noise 

and signal plus noise distributions. (PW, AS, GE) 

32 months Complete necessary modeling and supply model 

predictions corresponding to data available from 

sonic-shaped forged samples. (ISU with support 

from AS) 

32 

months 

Utilize sonic-shaped forging scan data to define 

noise distribution. (GE, PW with support from 

ISU) 

Report documenting the revisions to the 

noise and flaw modeling developed in this 

subtask and supply the modified model 

predictions. 

36 months Utilize sonic-shaped forging scan data to estimate 

the flaw-signal distribution and to compare with 

model prediction to define the deviation 

distribution. Apply the generalized methodology to 

estimate POD of synthetic hard alpha inclusions. 

(ISU with support from GE, PW) 

36 

months 

Compare with ahat vs. a and the R e methods. 

(GE with support from PW) 

Report assessing the adequacy of POD 

predictions of the physical/statistical 

model-based methodology developed in 

this program, based on comparison with 

the ahat vs. a and the Re methods, and 

describing and illustrating the advantages 

of the new methodology. 

Development of the Capability to Make 

Predictions of the Local POD in a Final 

Forging Geometry 




Original 

Date 

Revised 

Date 


24 months Analyze results (anisotropy, geometry effects) of 

Production and Inservice Inspection Tasks for 

implications to POD as a function of position in 

typical forging geometries. (ISU with support from 

AS, PW) 

27 months Define implementation plan for POD as function of 

position. (GE with support from ISU, PW, and 

AS) 

30 

months 

Report providing default POD curves for 

titanium forgings, for both production 

and in-service inspections, for use by the 

OEMs and FAA in life management/risk 

assessment studies. 

30 months Initial estimates of POD and PFA for sonic-shaped 

titanium forgings based on use of the FBH, SHA, 

CBS data, and field finds. 

36 months Complete modeling tools for the effects of 

geometry on flaw response and noise 

distributions. (ISU with support from PW) 

36 months Revised estimates of POD as a function of forging 

geometry, including effects of anisotropy, 

curvature, and position within the forging. 

38 months Complete experimental validation of modeling 

tools. (PW with support from GE, AS) Complete 

the development of the methodology needed to 

account for positional effects on POD. (ISU with 

support from GE, PW, and AS) 

40 months Compare with ahat vs. a and the R e methods. 

(GE with support from ISU and PW) 

42 months Provide updated methodology with POD as 

function of position as an output. (ISU) 

Improvements/Transfer of the POD/PFA 

Methodology Software to OEMs 

ongoing Modify the modeling software if and when 

necessitated by experimental data. (ISU) 

40 months Provide OEMs with integrated software containing 

flaw response and noise models as influenced by 

anisotropy and geometry. (ISU) 

48 months Review results for effects of introducing numerical 

approximation methods to the flaw response 

surface to speed the operation of the new 

methodology. (ISU, with support of AS, GE, PW) 

52 months Complete development and integrate validated 

methods to add noise to flaw response in c-scan 

images in the presence of anisotropy. (ISU with 

support from PW) 

60 months Provide OEMs with final software and procedure 

packages. (ISU) 

60 

months 

Report describing the technical details of 

the POD prediction methodology for 

sonic-shaped and final geometry forgings. 




Original 

Date 

Revised 

Date 


POD for Titanium Forgings 

48 months Apply the generalized methodology to estimate 

improvements in POD afforded by developments 

of Task 1.3. (ISU with support from GE) 

ongoing Update POD estimates for naturally occurring 

flaws in Ti alloys as field find data become 

available. (ISU with support of GE, PW, and AS) 

Deliverables: 

Original 

Date 

Revised 

Date 


12 months White-paper defining a method for predicting POD 

for sonic-shaped forged parts. 

30 months Initial estimates of POD and PFA for sonic-shaped 

titanium forgings based on use of the FBH, SHA, 

CBS data, and field finds. 

Ongoing Revised estimates of POD as a function of forging 

geometry, including effects of anisotropy, 

curvature, and position within the forging. 

30 months Report providing default POD curves for titanium 

forgings, for both production and inservice 

inspections, for use by the OEMs and FAA in life 

management/risk assessment studies. 

36 months Report assessing the adequacy of POD 

predictions of the physical/statistical model-based 

methodology developed in this program, based on 

comparison with the ahat vs. a and the R e 

methods, and describing and illustrating the 

advantages of the new methodology. 

60 months Report describing the technical details of the POD 

prediction methodology for sonic-shaped and final 

geometry forgings. 

60 months Prototype software implementing the methodology 

and associated flaw and noise response models 

for POD prediction as a function of inspection 

parameters, position in forging, and flaw 

characteristics. 

Third draft of white-paper to be 

completed in January 

Metrics: 

Procedures will be developed for estimating the POD of sonic shaped forgings and of final forging 

geometries as a function of position. Success will be indicated by the incorporation of these 

procedures by the OEMs in their life management programs. 

The ability of response models to predict flaw signals will be measured against the goal of having the 

predicted ultrasonic flaw response be within 3dB of experimental values at least 95% of the time when 

considered over typical inspection modalities. 

The ability to predict noise distributions will be measured against the goal of having predicted 

ultrasonic noise response within 3dB of experimental values at least 95% of the time when considered 

over typical inspection modalities. 




The development and transfer of the software for POD/PFA curve generation will be considered 

successful if it is utilized by the members of ETC and the Rotor Integrity Subcommittee of AIA in life 

management decisions. 

Estimates of the POD of hard-alpha defects in sonic-shaped and final forging geometries will be 

provided to the FAA and members of the ETC and Rotor Integrity Subcommittee. These estimates will 

be judged adequate if they compare favorably with predictions of existing POD methodologies for 

inspection situations in which such POD values can be obtained and if they provide sensible 

predictions in cases in which the existing methodologies cannot do so. 


Date 

June 14-15, 

1999 

September 16, 

1999 

November 17, 

1999 

Description 


Workshop to detail the approach for POD for Forgings. Included review of first draft of white 

paper and assignment for preparation of chapters of the document. 

Semi annual review with the FAA held in Kansas City. 


Date 

Description 




Project 3: 

Task 3.1: 





POD of Eddy Current 

Inspections in the Field 

Team Members: 

AS: Joe Chao, Mike Gorelik 

GE: Dick Burkel, Derek Sturges, Bill Tucker 

ISU: Bill Meeker, Norio Nakagawa, Bruce 

Thompson 

PW: Chuck Annis, Kevin Smith, Dave 

Raulerson 



Objectives: 

• To develop a new methodology for estimating the POD and PFA of eddy current (ET) inspections 

in the field which facilitates prediction of POD and PFA for specific changes in test parameters, 

surface conditions, material noise characteristics and feature geometries in a rapid fashion without 

the need to construct extensive specimen sets. 

• To validate that methodology by comparing its POD results to corresponding predictions of 

existing methodologies, such as the a-hat versus a model, when sufficient data exists to support 

that comparison. 

• To apply the methodology to the estimation of POD/PFA of inservice inspections of flat plates and 

slots. 

• To transfer the resulting software and procedures to the OEM’s for their use in life management 

calculations. 

Approach: 

As in the previous work on UT, the methodology will be based on the determination of the distributions 

of signal and of noise, with physical models of the measurement process being used to allow the 

maximum information to be obtained from limited experimental data. Special emphasis will be placed 

on the needs imposed by the development of field durability issues. 

The incorporation of physical models of the inspection adds flexibility and extensibility to the 

methodology, while reducing the cost. In general, physical models make parametric studies 

inexpensive, by repeated computations of output signals for a wide range of inspection parameters. 

The specific benefits of the models used in POD/PFA analyses are twofold: 

• The model-assisted POD/PFA estimation significantly reduces the specimen preparation, 

compared to a purely experiment-based POD estimate. The economic benefit is substantial for 

flat-surface geometry since only a handful of crack specimens are sufficient to provide 

normalization and model predictions can then cover a wide range of parameters. The benefit is 

even more substantial when complex geometries are considered because, without models, one 

must prepare a large number of specimens of varying defect sizes and conditions to perform POD 




analyses for each new inspection geometry. The expense of this approach often leads to a best 

effort approach rather than a rigorous statistical study of the required number of samples. 

• Models make POD/PFA results transferable. For instance, suppose that the distributions have 

been determined for a given probe and the POD/PFA estimated. The model can then be used to 

transfer this POD/PFA result to another probe, with appropriate correction factors, because of the 

model’s ability to reliably predict relative signal strengths between one probe and another. Also, 

the model allows results to be transferred from one geometry [e.g., straight edges] to another 

geometry [e.g., slot edges]. Collectively, the use of models can reduce the cost and time 

requirements of POD/PFA analyses to more manageable levels in an environment where both 

inspection demands and opportunities are increasing. This results not only in cost savings, but 

more importantly, increases the likelihood that formal POD/PFA estimates will be made with 

enhancement to safety and quantification of the benefits now possible. 

Figures 5 and 6 present flow diagrams of the work plan that has been developed to accomplish these 

goals, as is discussed in detail in the following text. 




a 

Notch 

& crack 

specimens 

h 

ET measurement 

b 

1D line/ 

2D raster 

scan data 

g 

Physical probe 

response 

model 

(flaw & geometry) 

c 

Data 

analysis 

Validation 

Noise 

component 

Flaw 

signal 

Geometry 

signal 

d 

e 

Monte Carlo 

(Scan index,etc) 

f 

i 

Stat. model of 

noise 

distribution 

Stat. model of 

signal 

distribution 

Crack 

morphology 

database 

j 

l 

k 

POD, PFA, 

ROC 

Figure 5. Detailed experimental and validation plan for EC methodology. 

Workshop and implementation plan: A kickoff meeting will be held to finalize a number of aspects of 

the program. Such a workshop was held to kick-off the UT work in Phase I and it had a major impact 

on the successful developments which followed. Included in the ET workshop will be a review of the 

current status of flaw response models, the definition of experimental plans for validating these 

models, the definition of the protocols for data capture and exchange in this validation process, a brief 

summary of the previous POD modeling work at ISU under the NIST funding, existing OEM 

applications of the EC models, the definition of the data needed to generate POD/PFA estimates, the 

discussion of questions associated with statistical rigor, and the development of definitions of such 

quantities as the PFA for continuously observed variables. (Nakagawa, Meeker, Thompson, 

Raulerson, Smith, Annis, Sturges, Burkel, Tucker, Duffy, Chao) 

Development of key additional ingredients for POD modeling: The basic tools for the flaw response 

models are already in place and formed the basis for feasibility demonstrations as noted in the Issues 

discussion. In this element a number of required extensions will be made. The primary model 

software is the BEM-based code, the development of which was initiated in the ETC Phase I, novel 

probe design program. The code has progressed recently to the point that it can deal with complex 

part geometries 

as well as general 

probe geometries 

and 

constructions. Of 

particular 

importance for 

this proposed 

effort is its 

capability to deal 

with two types of 

probes of high 

2 

Workshop 

& 

Implementation plan 

7a-7l 

6 

8 

9 

10 

Key 

additional 

ingredients 

Bolt hole 

or 

slot demonstr. 

Second 

generation 

methodology 

3a-3l 4 5 

First 

Flat plate 

generation 

demonstration 

Validation 

methodology 

Validation 

Third 

generation 

methodology 

Figure 6. Overall framework for development and validation of the EC methodology. 




current interest, i.e., differential reflection and wide-field probes, and with complex geometries such as 

the edges of a slot. The code has been validated against experimental data from edge crack 

inspections with air-core coil probes. It is therefore a crucial component of the project to validate the 

BEM code experimentally against data from the project-specific inspection conditions, namely cracks 

in flat plate and slot geometries, with differential-reflection and wide-field probes. Such experimental 

validations will be performed, as discussed below. In this work element, the theoretical comparisons 

will be made and model modifications made as needed. FEM-based models will also be used as a 

tool for cross-checking on the accuracy and validity of the BEM-based code. Practical inspection 

methods for complicated geometry often include methods for edge signal suppression. These will be 

reviewed and extended as needed, and methods will be developed for the characterization of their 

capability to reduce this component of noise. (Nakagawa, Meeker, Thompson, Raulerson, Smith, 

Annis, Sturges, Burkel, Tucker, Duffy, Chao) 

Application to a simple geometry: flat plates: The elements of the new methodology will be 

demonstrated by predicting the POD of notches and fatigue cracks in flat plates. Both differential 

reflection and wide field probes will be considered. A set of samples containing representative 

notches and cracks will first be obtained. These will be scanned to develop a data base, from which 

smaller data bases of noise and flaw response signals can be extracted. The noise data will be 

analyzed to yield a statistical model of the noise distribution, including its functional form and 

procedures for determining its parameters. The data will also be analyzed to determine the extent to 

which the noise is controlled by surface finish, microstructure, or other effects. The flaw signals will be 

used to validate the physical models for flaw response. These, as well as the noise distribution, will 

form the basis for the formulation of a physical model for the signal distribution. In the formulation of 

this model, attention will be paid to providing “hooks” which will allow a crack morphology database to 

be introduced at a later time (the development of such a database is not priced in this proposal). From 

the statistical models of noise and signal, POD, PFA and ROC curves will be determined. 

Based on the flat-plate demonstration, a first generation methodology will be specified. This will 

include procedures for each of the steps mentioned above. The methodology will be validated by 

exercising it on a set of existent samples and comparing the results to those of existent methodologies 

such as a-hat versus a. The conditions under which one or the other breaks down and the degree of 

agreement between their predictions will be noted and interpreted. Particular attention will be paid to 

the sparseness of data that can be accommodated by the new methodology, and the time that would 

be required for its implementation in the field. After validation, the new methodology will be used to 

make predictions of POD, as influenced by a variety of parameters, for use by the lifing community. 

(Nakagawa, Meeker, Thompson, Raulerson, Smith, Annis, Sturges, Burkel, Tucker, Duffy, Chao) 

Application to a complex geometry: blade slots: A demonstration will then be conducted on a blade 

slot, using a differential reflection probe. The same steps will be followed as in the flat plate 

demonstration, modified by insights gained in the formulation of the first generation methodology, and 

considering the edge geometry signals as sources of noise in the analysis of the data. Poorly 

managed edge responses can easily mask defect responses. One must assume that the inspection 

procedure incorporates appropriate mechanisms (e.g., by correct choices of probes and scans, and/or 

by signal processing) so that the edge contamination is suppressed. This is the reason for the 

consideration of the differential reflection probe, which is frequently used to suppress edge responses 




in the field. The edge signal remaining is effectively a source of noise. Our new POD/PFA 

methodology will be designed to quantify the edge-suppression capabilities as well as the other 

sources of noise. Once the signal and noise distributions are determined, following procedures 

already discussed, predictions will be made of the POD, PFA and ROC. 

Based on the experiences gained in the blade slot demonstration, a second generation methodology 

will be formulated. This will include procedures for each of the steps mentioned above. The second 

generation methodology will be validated by exercising it on an independent set of blade slot samples 

and comparing the results to those of existent methodologies such as a-hat versus a. The conditions 

under which one or the other breaks down and the degree of agreement between their predictions will 

be noted and interpreted. Particular attention will be paid to the sparseness of data that can be 

accommodated by the new methodology, and the time that would be required for its implementation in 

the field. The new methodology will be used to make predictions of POD, as influenced by a variety of 

parameters, for use by the lifing community. (Nakagawa, Meeker, Thompson, Raulerson, Smith, 

Annis, Sturges, Burkel, Tucker, Duffy, Chao) 

Improvement/transfer of the POD/PFA methodology software to the OEMs: In order for the new 

methodology to have full impact on the damage tolerant design and management of rotating 

components of aircraft engines, it is essential that the necessary tools, i.e., software for implementing 

the methodology, the associated modules for predicting flaw and noise response as influenced by 

geometry, and materials characterization procedures to efficiently provide input to them, be in a form 

that can be readily used by the OEMs. These tools will be developed, incorporating the results of the 

previously described major work elements. For example, procedures will be specified for the 

determination of the signal and noise distributions, defining the relative roles of empirical data and 

physical models. A final form of the methodology will be produced, including software incorporating all 

experiences gained in the execution of the subtask. This will be transferred to the OEMs and 

documented in a final report. (Nakagawa, Meeker, Thompson, Raulerson, Smith, Annis, Sturges, 

Burkel, Tucker, Duffy, Chao, Gorelik) 


1998. 


To coordinate efforts with the in-service subtasks, Rob Stephan communicated regularly about their 

subtask progress. The provided materials consisted of the minutes of their group meetings, the list of 

ET/UT specimens, the characteristics of the probes to be used, particularly those of the wide-field 

type, and information about the updated data acquisition software. In addition, Thadd Patton provided 

the POD Group with an actual series of measurement data taken with the SECAP (single-element 

eddy current array probe). Some of these information exchanges took place in conjunction with the 

white paper development, as described below. 

Progress was made to generate the white paper for the EC POD methodology. Particular attention 

was paid to amplification of the “Data Requirement” section. Substantial accomplishment was made 

during the conference call held on 12/09/99, attended by Joe Chao, Derek Sturges, Dave Raulerson, 

Bill Meeker, Norio Nakagawa, and Sridhar Nath, as well as Rob Stephan and Thadd Patton. During 




the call, two main concerns were raised and discussed; one is about the type of scans needed, and the 

other has to do with adequacy of the data to be taken in the in-service subtask. 

First, Stephan commented about the nature of scans described in the draft white paper and shown in 

the accompanying example-data set, which showed 2D raster scan data. He contended that the widefield 

probe scans would not be characterized as “raster,” since, by nature, the extended field probe 

permits large step sizes. Nakagawa responded, with concurrence by Raulerson, saying that raster 

scans are not required, as long as sufficiently redundant measurements with over-sampling are done 

so that the data will contain sufficient noise information. Stephan suggested to look at the SECAP data 

for confirmation, and proposed Patton to provide the data. Patton agreed, and later sent out the 

aforementioned data set. 

Second, Derek Sturges raised an issue regarding potential data limitation toward POD “validation.” 

Naturally, the In-service Tasks have their own goals to meet, and thus, understandably, are not 

necessarily structured to produce statistically sufficient data to validate POD results. For instance, 

Sturges contends, perhaps ~40 crack specimens may be desirable per inspection geometry to carry 

out the convincing POD analysis. Should this Task prepare to augment the measurement plan with 

additional validation measurements? Two points were immediately obvious: One, the issue is too 

important to resolve during a single phone call. Two, this Task is not funded to do additional 

measurements. Besides, it is up to each of OEMs to decide how precisely the POD methodology 

ought to be validated within usual resource limitations. Our current position is that the issue will be revisited 

in the course of development, while we figure out what can be done within the given project 

resources, such as utilizing existing measurement data and/or specimens, and perhaps performing a 

small amount of noise measurements. 


Complete the white paper, in which detailed architecture of the POD methodology for eddy current 

inspection and the implementation plan for its adaptation will be laid out. 

Continue coordination with the in-service subtasks to complete the definition of data requirements for 

generating POD/PFA estimation. 

Milestones: 


Date Date 


Workshop and Implementation Plan 

6 months Establish implementation plan for adaptation of 

the methodology to eddy current inspection. 

Define data needed by Inspection Systems 

Capability Working Group to generate POD/PFA 

estimates and provide guidance to Inservice 

Inspection working group. (All) 

Application to a Simple Geometry: Flat Plates 

18 months Complete flat plate demonstration. (AS, GE, PW 

with support from ISU) 

24 months Complete formulation of first generation 

Implementation plan will be 

completed in first quarter of 

2000 based on accelerated 

3.1.2 white-paper. Joint 

conference have been held 

with In-service team to define 

data needed. Interaction will 

continue. 




Original 

Date 

Revised 

Date 


methodology. (ISU with support from PW, GE, 

AS) 

30 months Complete validation of first generation 

methodology. Provide updates to default POD 

curves for flat plate to RISC. (PW with support 

from ISU, GE, AS) 

30 months Validation of the first generation methodology 

Development of Key Additional Ingredients for 

POD Modeling 

30 months Complete development of key additional 

capabilities of physical models. Complete 

development of methods to characterize edge 

suppression algorithms. (ISU with support from 

AS, PW, GE) 

30 months Development of additional capabilities of physical 

models along with edge suppression algorithms. 

Application to a Complex Geometry: Blade 

Slots 

36 months Complete blade slot demonstration. (PW, AS, GE 

with support from ISU) 

40 months Complete formulation of second generation 

methodology. (ISU with support form PW, AS, 

GE) 

52 months Complete validation of second generation 

methodology. Provide updates to default POD 

curves for slots to RISC. (PW, AS, GE with 

support from ISU) 

52 

months 

Validated POD/PFA methodology for ET 

inspection based on signal and noise 

distributions which incorporates false call 

considerations, can be applied to sparse 

data and can predict the results of similar 

inspections for which no data is available. 

Improvement/Transfer of the POD/PFA 

Methodology Software to the OEMs 

52 

months 

52 

months 

60 

months 

60 

months 

Estimates of POD/PFA for ET inspection 

improvements made with ETC tools. 

Updates to the default POD curves for 

RISC documents. 

Deliver third generation POD/PFA 

methodology to OEMs and provide final 

report. (ISU with support from PW, AS, 

GE) 

Prototype software made suitable for 

implementation of the methodology by 

the OEMs. 




Deliverables: 

Original 

Date 

Revised 

Date 


52 months Validated POD/PFA methodology for ET 

inspection based on signal and noise distributions 

which incorporates false call considerations, can 

be applied to sparse data and can predict the 

results of similar inspections for which no data is 

available. 

52 months Estimates of POD/PFA for ET inspection 

Milestones: improvements made with ETC tools. 

52 months Updates to default POD curves for RISC 

documents. 

60 months Prototype software suitable for implementation of 

the methodology by the OEMs. 

Metrics: 

The methodology developed for estimating POD of eddy current inspections will be judged successful 

if three conditions are met. For data sets such as those used by existent methodologies, the new 

methodology should make comparable POD predictions. For sparse data sets, the new methodology 

should make sensible predictions when none are made by existents empirical methodologies. In 

either case these predictions should be able to be obtained with less expense and more rapidly than 

with existent methodologies. 

The updates to the POD curves will be judged successful if they are incorporated by RISC in life 

management guideline materials. 

The software produced to implement the methodology will be judged successful if it is utilized by the 

members of ETC and the Rotor Integrity Subcommittee of AIA in life management decisions. 

The estimates of improvements afforded by the advances in the ETC will be judged successful if they 

impact the acceptance of these technologies by the OEMs. 


Date 

June 14-15, 

1999 

September 17, 

1999 

Description 


Workshop to detail the approach for POD for EC. Included review of first draft of white paper 

and approach to the methodology. 


Date 

Description 




ETC Program Management Team Members: 

AS: Tim Duffy 

GE: Jon Bartos 


PW: Kevin Smith 

WTA: Hans Weber 


Program initiation date: April 26, 1999 

Objectives: 

• To support the development, integration and implementation of technology generated as part of 

the ETC Phase I and Phase II programs 

• To manage all program issues that are of a scheduling, reporting, programmatic, financial, or 

technical nature including the day-to-day activities of ETC and responsibilities related to 

deliverables and milestones 

• To ensure communication between the various ETC technical teams, between other funded FAA 

inspection programs, and between other relevant industry groups such as TRMD and RISC as 

well as the portion of the industry not participating in the funded program 

• To ensure an integrated ETC II program. 

Approach: 

The ETC Technical Team consists of over 50 scientists and engineers from the four organizations. 

Brief capabilities statements from key contributors are provided in the Program Resources section of 

the proposal. In an effort to ensure coordination across the program, primary responsibility for the 

technical areas rest with the PMT focal points established as follows: 

Billet Inspection: Jon Bartos 

Forging Inspection: Jon Bartos and Tim Duffy 

Inservice Inspection: Kevin Smith 

Inspection Systems Capability and Assessment: Ron Roberts 

Fluorescent Penetrant Inspection: Tim Duffy 

Phase I of the ETC successfully used a combination of quarterly meetings, monthly conference calls, 

and annual cross-coordination meetings to ensure communication and progress internal to the ETC. 

The primary management tool for the individual tasks will be the monthly conference calls. As in 

Phase I, the monthly conference calls provide a status update to all participants in the call and tracking 

of action items as well as broader programmatic updates to all members of the team. The monthly 

call will be supplemented by approximately quarterly face-to-face meetings within the technical task 




that will last on the order of one day. The need for these meetings is determined by the technical 

teams. They will occur at various member locations. Annual meetings will be held in which all 

members of the program meet to enable cross task coordination of the technical participants and the 

Sponsor. The ETC Open Forum was successfully used to communicate that progress to the rest of 

the industry and the FAA as evidenced by unfunded participation by Rolls Royce in the Contaminated 

Billet Study. ETC also participated in various reviews such as with the New England Directorate and 

the Technical Oversight Group for Aging Aircraft (TOGAA). We anticipate continuation of these 

activities including adding to that further coordination by the PMT with other funded programs as 

defined above. Based on the accomplishments delivered in Phase I and the technical strength of the 

Phase II team, we anticipate a strong Phase II program. 

An independent facilitator has been added at FAA request with Hans Weber of Weber Technology 

Associates serving that function. The individual shall provide administrative oversight required to 

support the FAA including serving as a non-voting chair of the PMT and coordinating various 

communication, meeting, and reporting requirements to the FAA. 

Objective/Approach Amendments: Objective remains as originally proposed in July 1998. The 

approach was modified in January 1999 to include an independent facilitator at the request of the FAA. 

Progress (October 1, 1999 –December 31, 1999):The Program Management Team (PMT) covered 

the following agenda: 

1. In a telecon on December 2, 1999, the PMT came to consensus agreement on the detailed SOW 

and work assignments for the proposal to resolve the questions raised by unexpected inspection 

results on the RDB. A copy of the SOW was submitted to the FAA. Subsequent to this agreement, 

ISU issued requests for quote to the OEMs, based on the SOW. ISU is preparing a quote for the 

POD task contribution to the RDB proposal. Once the ETC II members have submitted their 

quotes, ISU will submit the RDB proposal to the FAA. The following sequence of events led up to 

the PMT’s completion of the SOW: 

• Following the POD workshop at ISU in September the PMT developed a detailed technical 

plan for solving the outstanding RDB questions. The recommendations made by the technical 

team at the workshop formed the basis for the plan. 

• During October certain additional technical information became available that was considered 

by the PMT in the development of the plan. The PMT then assigned three basic levels of 

priority to the recommended tasks: ”Must do”, “may have to do” if the “must do” tasks do not 

lead to complete resolution, and “nice to do, but not essential”. The PMT eliminated the third 

category from the plan as part of its overall effort to control the cost of the RDB work. 

• By October 28 the PMT had reached agreement on the technical plan consisting of tasks in the 

first two priority levels. On November 1 it briefed the EIOB. The EIOB raised several 

questions which were resolved with the EIOB on November 17. On December 2 the PMT 

came to final agreement on the detailed SOW and on a plan for work assignments. The work 

assignments were guided by the principle of providing best value to the FAA. 

• The PMT convened numerous telecon “meetings” throughout the months of October and 

November to complete the RDB plan. 




2. On November 1 the EIOB conducted the first ETC II program review. The status of the entire 

program was reviewed with emphasis placed on problem areas, such as the RDB. The EIOB 

asked for more information on the RDB (see above). 

3. On November 18 the FAA conducted the first semi-annual review of the ETC II program at Kansas 

City, immediately following on to the second annual meeting of the Airworthiness Assurance 

Center of Excellence. The review was positive. The FAA asked the PMT to develop ideas for 

speeding up its decision-making process. In response, the PMT has committed to nominating 

alternate members who can be authorized to vote on decisions at PMT meetings. The PMT is 

considering further ideas. 

4. In response to a request from Tim Mouzakis for Quarterly Reports (QRs) that can be distributed to 

parties who are not signatories to the ETC proprietary information agreement, the PMT developed 

the following approach: Two versions of the QR will be generated, one for open, the other for 

restricted distribution. The main difference between the two is that all proprietary information will 

be eliminated from the unrestricted version. The PMT will generate one QR retro-actively to the 

beginning of the technical work in Phase II in June. The first unrestricted QR will cover the fourmonth 

period June through September, 1999. 

5. The second QR was submitted. 

6. Gantt charts were developed and presented at the semi-annual meeting. 

7. During November Lisa Brasche, the PMT member representing ISU, was promoted to the position 

of interim Executive Director of the FAA Center of Excellence for Airworthiness Assurance 

(AACE). ETC II is one of the projects under AACE (it is the single largest project). Ron Roberts 

from ISU joined the PMT as the new ISU member. 


1. All PMT members will work with their respective organizations to respond to the RFQs from ISU 

for the RDB proposal. They will generally be of assistance in getting the formal proposal prepared 

and submitted to the FAA. 

2. All PMT members are prepared to render assistance, as required, during negotiations on the RDB 

proposal. 

3. The third QR will be submitted in two versions, restricted and unrestricted (see above). The 

unrestricted version for the first four months (combining the first two QRs) will also be submitted. 

The unrestricted version will be submitted following the restricted one. 

4. Develop further ideas for speeding up the PMT’s decision-making process. 





Date 

Description 

May 13-14 FAA Kickoff meeting held in Cincinnati with Rick Micklos, Bruce Fenton, Chris Seher and Tim 

Mouzakis in attendance. Tony Murphy, EIOB, attended. 

June 14 - 17 ETC Phase II Technical Kickoff meeting held in West Palm Beach with Rick Micklos and Al Broz 

in attendance. An executive overview was also provided to Chris Seher. It was attended by 

Bryant Walker of the EIOB. 

June 30 Phase II Overview provided to representatives of the New England Directorate at the Burlington 

FAA Offices. Rick Micklos, Bruce Fenton, Chris Seher and Al Broz were attending. 

Sep 15-17 POD Workshop at ISU. Detailed plan developed for resolving RDB questions. 

Sep. 28-29 Review meeting with UniWest on ETC scanner 

Nov. 18 Semi-annual review meeting held at Kansas City, MO, with Rick Micklos and Cathy Bigelow in 

attendance. 


Date 

Description 

May 13-14 FAA Kickoff meeting held in Cincinnati. Presentations included overviews for each of the tasks, 

management plan, and communication plans. 

June 14 - 17 Presentations for each of the tasks and subtasks as necessary to initiate the technical program. 

June 30 Phase II Overview which focussed on the relationship between the ETC program and current 

FAA initiatives. 

Nov. 18 Semi-annual review meeting at Kansas City. Presentations on all technical subtasks were given, 

as well as on the management task.

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