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03 AIR TRANSPORTATION AND SAFETY
tions with additional studies could be used in the development of
better occupant safety systems.
Author
Air Bag Restraint Devices; Finite Element Method; Human Factors
Engineering; Deformation; Loads (Forces); Inflatable Structures;
Impact Damage
20000032865 Textron Bell Helicopter, Fort Worth, TX USA
APPLICATION OF DAMAGE TOLERANCE TO INCREASE
SAFETY OF HELICOPTERS IN SERVICE
Krasnowski, Bogdan R., Textron Bell Helicopter, USA; Application of
Damage Tolerance Principles for Improved Airworthiness of
Rotorcraft; February 2000, pp. 7-1-7-8;InEnglish; See also
20000032859; Copyright Waived; Avail: CASI; A02, Hardcopy
In the past, all helicopters have been designed to safe-life
requirements. Introduced in October 1989, FAR 29.571 at Amendment
28 requires damage tolerance substantiation for transport
category helicopters. Therefore, the majority of helicopters currently
in service were designed to safe-life requirements. In general, the
safe-life approach has proven to be adequate. However, there have
been a number of field problems with cracking components, which
lend themselves to the application of a damage tolerance approach.
Damage tolerance analysis allows addressing the safety of the
cracking components by: Evaluation of the field cracking, supported
by the laboratory evaluation of the field-returned cracks; Establishment
of the inspection interval in conjunction, if necessary, with
operation limitations; and Specification of fixes to be applied to the
structure to either increase the inspection limit and/or lift the operation
limitations. To accomplish the above listed tasks, crack growth
analysis is performed using the appropriate usage spectrum and the
flight load survey data. If necessary, usage spectrum reviews and
additional flight load surveys could be required. The crack growth
analysis results are verified by the laboratory evaluation of the
cracked components, and if necessary by the additional crack
growth testing of the field-returned components with cracks or the
pre-cracked components.
Author
Crack Propagation; Tolerances (Mechanics); Damage; Helicopters;
Cracks; Aircraft Safety; Helicopter Design
20000032866 Agusta A. Finmeccanica Co., Cascina Costa di
Samarate, Italy
AGUSTA EXPERIENCE ON DAMAGE TOLERANCE EVALUA-
TION OF HELICOPTER COMPONENTS
Mariani, Ugo, Agusta A. Finmeccanica Co., Italy; Candiani, Luigi,
Agusta A. Finmeccanica Co., Italy; Application of Damage Tolerance
Principles for Improved Airworthiness of Rotorcraft; February 2000,
pp.8-1-8-12;InEnglish; See also 20000032859; Copyright
Waived; Avail: CASI; A03, Hardcopy
Within the fatigue evaluation of the EHl0l, Agusta has carried
out a specific program of flaw tolerance evaluation of the primary
loading path. The program is close to completion and this paper
provides a summary of the most relevant results. For composite
components, damage size was increased considering both manufacturing
discrepancies greater than the minimum quality standard
and impact damages clearly detectable during visual inspections.
The favourable data achieved are based on the ‘no growth’ concept.
The metal parts of the main rotor head were evaluated by enhanced
safe life method and fail safe capability. The slow crack growth
approach was instead applied for the Rear Fuselage End Fittings,
which connect the Tail Unit. All these evidences can be used in
addition to the comprehensive safe life evaluation of the aircraft to
improve the maintenance and the repair actions. Based on this
experience, application of flaw tolerance criteria will be carried out on
the new helicopters in development phase.
Author
Eh-101 Helicopter; Composite Materials; Crack Propagation; Impact
Damage; Tolerances (Mechanics); Helicopters; Aircraft Structures;
Fiber Composites
20000105075 Department of the Air Force, Kirtland AFB, NM USA
THE COST/BENEFIT OF AGING ON SAFETY AND MISSION
COMPLETION IN AVIATION PROFESSIONS
King, R. E., Department of the Air Force, USA; Operational Issues of
Aging Crewmembers; August 2000, pp. 17-1 - 17-6; In English; See
also 20000105060; Copyright Waived; Avail: CASI; A02, Hardcopy
16
The suspected detrimental effects of aging lead to concerns
about aging pilots in civilian and, to a lesser extent, military flying.
The typically superior cognitive ability of all pilots, and experience of
older pilots in particular, however, render them a valuable asset and
dictate they be carefully assessed when concerns about their
cognitive ability arise.
Author
Cost Effectiveness; Age Factor; Safety
20010002554 European Research Office (US Army), Army Research
Lab., London, UK
SAFETY AND SERVICE DIFFICULTY REPORTING
Sampath, S. G., European Research Office (US Army), UK; Aging
Engines, Avionics, Subsystems and Helicopters; October 2000, pp.
7-1 - 7-12; In English; See also 20010002548; Copyright Waived;
Avail: CASI; A03, Hardcopy
Today, safety is considered to be of highest importance in most
societies. In the context of the military, safety is essential to averting
loss of life and damage to a high-value asset. While safety may take
second place to winning a war, its importance is further accentuated
because of its connotation to battlefield readiness. There have been
numerous instances to illustrate this last point. To wit: (1) Widespread
Fatigue Damage (WFD) was discovered in ‘weep holes’ of
fuel tanks of some C-141 military transport airplanes. Because of the
loss of minimum residual strength, with the attendant risk of catastrophic
fracture posed by WFD, the entire fleet had to be grounded
and an expensive refurbishment program had to be undertaken
before the fleet was deemed to be airworthy. In this instance, the
unsafe condition was detected and corrected quickly, so no lives
were lost nor did any of the airplanes in the fleet suffer catastrophic
damage. However, the grounded aircraft were certainly not battleready
for a certain length of time. Had they been sent into battle, they
would have had to be operated under severe flight restrictions and,
thus, their utility to serve the purpose of the deployed forces would
have been very restricted. Had they been deployed without any
restrictions, in all probability they would have been unable to
complete their missions and the Air Force could have lost valuable
aircraft assets. Also, the necessary logistic support to properly carry
out tactical operations in the battlefield would not have been available.
(2) WFD was the primary cause of a highly publicized air
accident involving a commercial aircraft. The wide publicity given to
that single accident, abetted by on-site video tape recording of the
condition of the aircraft after it had landed, shook the confidence of
the public in the safety of commercial aviation. As a result, inspection
and refurbishment of 3000 jet transport airplanes among a fleet of
about 5000 was mandated by the authorities, to be undertaken on an
urgent basis. The economic impact of this mandate on the airlines,
the aircraft manufacturer and the flying public was high and resulted
in numerous complaints to the regulatory authorities. It must be
noted that since that time more than twelve years have elapsed
without a single accident attributable to WFD.
Author
Aircraft Reliability; Damage; Fatigue (Materials); Fractures
(Materials); Aircraft Safety; Flight Safety; Accident Prevention
20010028487 European Research Office (US Army), London, UK
SAFETY AND SERVICE DIFFICULTY REPORTING
Sampath, S. G., European Research Office (US Army), UK; Aging
Aircraft Fleets: Structural and Other Subsystem Aspects; March
2001, pp. 12-1 - 12-13; In English; See also 20010028476; Copyright
Waived; Avail: CASI; A03, Hardcopy
Today, safety is considered to be of highest importance in most
societies. In the context of the military, safety is essential to averting
loss of life and damage to a high-value asset. While safety may take
second place to winning a war, its importance is further accentuated
because of its connotation to battlefield readiness. There have been
numerous instances to illustrate this last point. To wit: Widespread
Fatigue Damage (WFD) was discovered in ‘weep holes’ of fuel tanks
of some C-141 military transport airplanes. Because of the loss of
minimum residual strength, with the attendant risk of catastrophic
fracture posed by WFD, the entire fleet had to be grounded and an
expensive refurbishment program had to be undertaken before the
fleet was deemed to be airworthy. In this instance, the unsafe
condition was detected and corrected quickly, so no lives were lost
nor did any of the airplanes in the fleet suffer catastrophic damage.
However, the grounded aircraft were certainly not battle-ready for a
certain length of time. Had they been sent into battle, they would