In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

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storage could result in BITE information not being recorded correctly (see alsosection 3.7.5).The components of the CPU module that were involved in storing and retrievingdata in memory were the CPU chip, companion ASIC, the wait-state RAM chip,and the other four RAM chips. As noted, testing of the wait-states did not revealany effects relevant to the occurrence.3.5 Review of ADIRU configuration and service history3.5.1 BackgroundTwo of the three known data-spike occurrences involved the same LTN-101ADIRU (unit 4167), and the other occurrence involved a unit with a similar serialnumber (unit 4122). Accordingly, the investigation examined the configuration andservice history of the two units to determine if there were specific aspects of theseunits that could be associated with the data-spike failure mode.3.5.2 Hardware configurationOverview of module and component batchesEach module of the ADIRU consisted of a printed circuit board (PCB) containingelectronic components. External contractors manufactured and populated the PCBswith components. When completed, the PCBs were delivered to the ADIRUmanufacturer, who tested the individual modules and then assembled and tested theADIRU as a complete unit.The ADIRU manufacturer reported that modules were ordered in lots of 50. Eachmodule was annotated with a part number and a serial number, and detailed recordswere kept so that a module’s service history could be tracked. In general, modulesfrom the same batch contained components from identical or similar batches.Most components were ordered in lots of approximately 500. For the CPU chip 135 , alife-time purchase was made to cover future production and spares. The CPU chipwas critical to the design of the ADIRU and a life-time purchase mitigated the riskof a future lack of supply or obsolescence. However, other components were notlife-time purchases, and they could be replaced with equivalent components overtime. These changes would not result in a design change or a corresponding partnumber change.Complex components within each module, such as memory chips, were annotatedwith a part number and usually had additional markings such as the productionbatch number, a manufacturing date code, and sometimes a serial number. Lesscomplex components, such as resistors, were not annotated with a part number,although they had a part number when they were ordered.The ADIRU manufacturer did not have records of the serial numbers, batchnumbers or date codes of the components within each module. Therefore, it was notpossible to track the service history of the components, or to easily compare the135Part number 80960MC, manufactured by Intel Corporation.- 130 -
component configurations of different units. Another ADIRU manufacturer advisedthat its tracking capability was also at the module level and not the componentlevel.In general, there can be variations between components that occur duringmanufacture or over their service life, even though they are built to a specificstandard and have the same part number. Components from the same batch willnormally be more similar than components from different batches.Module and component batches for ADIRUs 4167 and 4122Both ADIRUs 4167 and 4122 were manufactured in August 2002. At the time ofthe data-spike occurrences (12 September 2006, 7 October 2008 and 27 December2008 respectively), their configurations were very similar. The two units had thesame part numbers for each module except for two sub-assemblies of the sensorelectronics module.The CPU modules that were used in both units 4167 and 4122 had the part number465474-03, and the serial numbers were 9-7315 and 9-7273 respectively (adifference of 42 in the build sequence). The two modules were built in adjacentbatches of 50 (9-7300 to 9-7349 versus 9-7250 to 9-7299).In addition to the CPU chip, the other key components in the two units’ CPUmodules had the same part numbers and came from the same or similar batches.More specifically:• The companion ASICs had the same part number 136 , and all other markingswere identical.• The wait-state RAM chips had the same part number 137 , and a visualexamination showed that all markings were identical for both units.• The RAM chips used for CPU data all had the same part number. 138 For unit4167, each of the four chips had identical markings and contained a ‘-9’ in theproduction code. For unit 4122 three devices had a ‘-10’ in a production codewhile one had a ‘-9’.Subsequent CPU modulesThe LTN-101 ADIRU’s CPU module was later redesigned to reduce costs and toinclude error detection and correction (EDAC). EDAC is used for detecting andcorrecting single-bit errors in RAM chips to give protection from single eventeffects (SEEs, see section 3.6.6). This change was a significant redesign andresulted in a new CPU module part number (466871-01). The EDAC wasperformed by a new ASIC, and all of the RAM chips used on the CPU module werereplaced with a different chip. 139136137138139Part number 5962-99A2001QXC, manufactured by AMI Semiconductor.Part number MT5C2564C, manufactured by Austin Semiconductor.Part number MSM8128JMB, manufactured by Mosaic Semiconductor.EDAC was functionally located between the CPU chip and the RAM and required more memoryto be available than in a design without EDAC.- 131 -
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ATSB TRANSPORT SAFETY REPORTAviatio
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Published by: Australian Transport
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3 FACTUAL INFORMATION: AIR DATA INE
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DOCUMENT RETRIEVAL INFORMATIONRepor
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TERMINOLOGY USED IN THIS REPORTOccu
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CSMCSSCVRDADSDCDGACDMCDMUEASAECAMED
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RAMRTCASATCOMSAESAOSDSECSEESEUSSASS
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FCPC design limitationAOA is a crit
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- xviii -
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associated with a master caution ch
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Figure 2: Aircraft track and key ev
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The crew decided that they needed t
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1.3 Damage to aircraftThere was sig
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• The flight crew provided inputs
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exceeding a predefined safe flight
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Table 1: Examples of ADIRU flight d
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Inertial reference partThe IR part
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ADIRS switching controlsIn normal o
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Processing by ADIRUs and FCPCsEach
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The information presented on the fl
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A system could flag its output data
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Table 4: Summary of indications for
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Figure 17: ECAM engine / warning di
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Table 6: Required actions associate
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For internal aircraft communication
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Table 7: Sequence of events (from t
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In summary, the source of most of t
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Summary of IR data for the occurren
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Figure 22: QAR plot showing oscilla
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QAR dataOverall, the QAR recorded 4
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Flight crew pitch inputsDuring manu
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They provided information for maint
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Table 11: Cockpit effect messages d
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Table 13: Troubleshooting data rela
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position 1 on QPA. Further details
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class 1 fault messages shown in Tab
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If there was a discrepancy between
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1.15 Survival aspectsInformation on
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did not identify any faults. The BI
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Comparison of the three occurrences
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1.17.2 Processes for reporting and
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2 FACTUAL INFORMATION: ELECTRICAL F
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monitored external systems that pro
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Each FCPC used a number of paramete
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AOA computation logicThe FCPC softw
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Figure 29: FCPC processing of sever
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Table 19: Characteristics of elevat
Page 99 and 100: Simulation of AOA values for the fi
Page 101 and 102: 2.2.2 Review of recorded flight con
Page 103 and 104: second PRIM 3 FAULT. The role of ma
Page 105 and 106: The ACJ was built around the princi
Page 107 and 108: • It stated that the identificati
Page 109 and 110: The second part of the V-cycle invo
Page 111 and 112: • Functional requirements. These
Page 113 and 114: 2.4.5 Safety assessment activitiesG
Page 115 and 116: equipment software and aircraft ins
Page 117 and 118: 2.5.4 Factors associated with the i
Page 119 and 120: it is very difficult if not impossi
Page 121 and 122: applicable to highly-integrated or
Page 123 and 124: Ongoing developmentsA range of rese
Page 125 and 126: To conduct an effective fault tree
Page 127 and 128: According to this model, accidents
Page 129 and 130: 3 FACTUAL INFORMATION: AIR DATA INE
Page 131 and 132: • inertial reference input/output
Page 133 and 134: 3.3 Examination of data-spike patte
Page 135 and 136: Figure 38: ARINC 429 word for an AO
Page 137 and 138: 3.3.4 Data-spike patterns for the 7
Page 139 and 140: Figure 43: Qualitative correlation
Page 141 and 142: etween the values of any of the fou
Page 143 and 144: 3.4.3 Calculating parameter valuesA
Page 145 and 146: 3.4.5 Packaging the ARINC 429 wordT
Page 147 and 148: 3.4.8 Transmitting data to other sy
Page 149: ARINC 429 packaging analysisThe ADI
Page 153 and 154: manufacturer reported such BITE dat
Page 155 and 156: 3.6 Potential trigger types3.6.1 Ba
Page 157 and 158: such as liquids or small loose frag
Page 159 and 160: wires). The electric 144 field stre
Page 161 and 162: Although the investigation could no
Page 163 and 164: 3.6.6 Single event effectsBackgroun
Page 165 and 166: until a few years ago, were not dir
Page 167 and 168: Unit testingIn 2005, as part of the
Page 169 and 170: that involved a NAV IR and/or NAV A
Page 171 and 172: EMI from other aircraft systems (su
Page 173 and 174: from ADIRU 1 was not correctly reco
Page 175 and 176: • Detected failure. Any failure w
Page 177 and 178: The ADIRU manufacturer’s analysis
Page 179 and 180: the aircraft and ADIRU manufacturer
Page 181 and 182: 4 FACTUAL INFORMATION: CABIN SAFETY
Page 183 and 184: Summary details of the cabin crew
Page 185 and 186: section, and the ninth flight atten
Page 187 and 188: Table 29: Significant cabin communi
Page 189 and 190: Figure 48: Example of damage to the
Page 191 and 192: 4.3.2 Seat belt examinationsSix pas
Page 193 and 194: The flight crew’s procedures requ
Page 195 and 196: takeoff, landing or when the seat-b
Page 197 and 198: Table 31: Levels of injuryInjury le
Page 199 and 200: 4.6.4 Injuries to seated occupants
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The percentage of occupants who wer
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Statistical analyses 197 were done
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passengers reported that they had h
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that seat belts should be worn only
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4.8.2 Handholds in the cabinThe FAA
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Figure 53: Overview of the 7 Octobe
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process needs to ensure that there
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and determine whether they could le
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useful in this case. If the EFCS sp
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5.3.2 Risk associated with the fail
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• All three events occurred in a
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place. Although aviation manufactur
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equiring cabin crew to enforce the
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With the information available to t
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ADIRU 1 affected the operation of a
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6 FINDINGSFrom the evidence availab
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• As of April 2010, the LTN-101 a
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did not illuminate. The new OEB (A3
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modifications were made to its guid
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this advice. At the time of the fir
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APPENDIX A: VERTICAL ACCELERATIONST
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APPENDIX B: FLIGHT RECORDER INFORMA
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APPENDIX C: POST-FLIGHT REPORTThe f
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APPENDIX D: OTHER DATA-SPIKE OCCURR
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Occurrence on 27 December 2008Overv
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Figure D2: FDR data for the 27 Dece
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ADIRU informationADIRU 1 was the sa
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APPENDIX E: ADIRU TESTINGTest plan
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Visual inspectionsExternal visual i
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(ADR) output databuses. Loading on
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Unit 4167 passed 2,223 of 2,272 tes
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dwells (sustained testing at a fixe
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APPENDIX F: AIRCRAFT LEVEL TESTINGI
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APPENDIX G: ELECTROMAGNETIC RADIATI
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cannot be ‘decoded’ by the rece
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APPENDIX H: SINGLE EVENT EFFECTSNot
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Factors affecting SEE exposureAn ai
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portions of memory are constantly b
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Depending on the form of EDAC, sing
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• crew actions: the passenger’s
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The questionnaire respondents were
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was centred across the passenger’
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Previous occurrencesThe seat belt m
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Australian turbulence eventsThe mos
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APPENDIX L: SEAT BELT USE IN ROAD V
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Table L1: Recent seat belt use rate
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US Federal Aviation AdministrationT
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APPENDIX N: SOURCES AND SUBMISSIONS
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Hanson, RJ 1987, Conducted electrom
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Tvaryanas, AP 2003, ‘Epidemiology
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In-flight upset - 154 km west of Le
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In-flight upset - 154 km west of Learmonth, WA, 7 October 2008,

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