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

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The redesigned CPU module was incorporated in all ADIRUs from serial number4385 (late 2002) onwards. The ADIRU manufacturer advised that it was also usedin some ADIRUs prior to serial number 4385, and it was incorporated when olderunits were returned for repair.3.5.3 Software versionThe ADIRU software was changed from time to time as updates and improvementswere incorporated. At the time of manufacture, units 4167 and 4122 had softwareversion -0312 installed. Updated versions were usually promulgated as optionalservice bulletins 140 , and operators could decide whether the advantages of installingan updated version of the software were sufficient to justify the logistics ofupgrading each aircraft (three ADIRUs per aircraft). The operator of QPA electednot to load software versions -0313 and -0314 in any of their ADIRUs.Software version -0315 was loaded on unit 4167 on 20 July 2005 and was theversion installed at the time of the 12 September 2006 occurrence. Software version-0316 was released in August 2008; it was the version installed on unit 4167 at thetime of the 7 October 2008 occurrence and it was also installed on unit 4122 at thetime of the 27 December 2008 occurrence. As far as could be determined, most ofthe LTN-101 ADIRUs had software versions -0315 and/or -0316 installed.3.5.4 Service historiesDetails of the service histories of units 4167 and 4122 are summarised in Figure 46.Notable features include:• Unit 4122 was removed from service three times for examination (two times forreported drift problems 141 ), and unit 4167 was removed once. The removalfrequency was normal for this type of unit.• Both units experienced a similar type of fault early in their service life thatinvolved temperature sensor failures. In both cases, the manufacturer replacedthe sensor electronics module and performed a thermal calibration. These werethe only faults of this type experienced on the operator’s fleet; however, themanufacturer advised that it was not an uncommon fault, with 24 casesoccurring across the world fleet of LTN-101s during the period from 2006 to2008. Both units had many hours of service following these repairs.• In addition to removals, both units had been associated with reported IR and/orADR faults that did not require removal. Such faults were not unusual (section3.9.2).• Unit 4122 experienced an IR 1 fault in July 2008, 5 months prior to the27 December 2008 data-spike occurrence. Available BITE data was consistentwith the fault being due to a type of SEE (section 3.6.6). The ADIRU140 Service bulletins are issued by aircraft, component, or engine manufacturers to provide operatorswith relevant service information. Not all service bulletins are safety-related, and compliance witha particular service bulletin can only be mandated by the State of Registry of an aircraft.141After many months or years of service, the drift rate of laser-ring gyro inertial systems can exceedthe allowable threshold and the unit needs to be re-calibrated. This is a relatively routinemaintenance requirement.- 132 -
manufacturer reported such BITE data was not uncommon, with over 100similar events reported across the world fleet since 2000.• Unit 4167 experienced an IR 1 fault in June 2006, 3 months prior to its firstdata-spike occurrence on 12 September 2006. Very little recorded data in theunit’s BITE was available for this period, but the available information indicatedthat the fault was not consistent with a similar type of SEE as occurred for unit4122 in July 2008.• Unit 4167 had operated for over 2 years after its first data-spike occurrencewithout any reported problems, and its software was replaced with a newversion during this period (as part of a routine upgrade).3.5.5 SummaryAs discussed in section 1.16.2, there was nothing unusual about the operationalenvironment associated with the three data-spike occurrences. Therefore, the factthat two of the three data-spike occurrences involved one unit (out of about 8,000)provided a strong indication that some aspect specific to the affected unitscontributed to the data-spike failure mode.The software installed on the two affected units was common to most of the units,and no software-related problems were found on the two affected units duringtesting (section 3.6.2). Therefore, it is probable that some aspect of the two affectedunits’ hardware was associated with the failure mode.The key hardware components in the CPU modules of units 4167 and 4122 werevery similar, but the number of other units that had the same level of similaritycould not be determined as component details were not recorded.- 133 -
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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
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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 and 150: ARINC 429 packaging analysisThe ADI
Page 151: component configurations of differe
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
Page 201 and 202: 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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- 233 -
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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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