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

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The information presented on the flight displays was generated by two displaymanagement computers (DMCs), based on inputs from the ADIRUs, FWS andother sources.1.6.8 Overview of avionics fault-detection processesTypes of faultsModern aircraft systems are composed of line-replaceable units (LRUs) 31 and otheritems of equipment, each of which includes many components. These units willoccasionally develop physical faults or failures. 32 The faults can be permanent,transient (appear for a short time then disappear), or intermittent (occur from timeto time). Transient and intermittent faults are often known as ‘soft’ faults.Hard faults can be reliably reproduced during operation or testing, whereas softfaults are more difficult to reproduce unless the circumstances that induced themare well known. With soft faults, the equipment behaviour will generally return tonormal after the equipment is rebooted or power is cycled.Self-detected faultsAircraft systems are designed so that the probability of an equipment fault is belowa specified level. 33 In addition, systems are designed so that they can manage theoccurrence of a fault using methods such as fault detection and equipmentredundancy.The fault-detection processes on the A330 are summarised in Figure 16. In generalterms, the aircraft’s systems were designed so that the primary means of detectingfaults was self-detection (that is, internal detection by the unit or system itself). If afault was self-detected, then it was easier to manage. For example, the system couldflag incorrect output data as invalid and other aircraft systems could then ignore it.Alternatively, some systems did not provide outputs to other systems, and could notrely on external fault detection.313233An LRU is a unit that, due to its size, weight and connections, could be easily removed during linemaintenance. It would be replaced with a serviceable unit, while the original was dispatched forrepair. The ADIRUs and FCPCs are examples of LRUs.In some situations, the term ‘fault’ is used to refer to an anomaly in the system or unit, whereas theterm ‘failure’ is used to refer to when the system or unit is unable to perform its functions (due toa malfunction or loss of function). In practice, manufacturers and operators use the termsinterchangeably, and they are used interchangeably in this report.Regulatory requirements for aircraft systems such as the EFCS are discussed in section 2.3, andthe aircraft manufacturer’s equipment specification for the ADIRUs is discussed in section 3.1.1.- 22 -
Figure 16: Overview of system fault reporting processesOn the A330, systems could self detect faults by using built-in test equipment(BITE) 34 and, depending on the system, a wide range of tests were conducted. If afault was self-detected, it was managed using the following actions:• depending on the severity of the fault:– flag any affected output data as ‘invalid’ so that other systems would not useit (see below)– stop the transmission of any output data– shut down the system.• send a message to the flight warning system (FWS), which generated ECAMmessages and other associated fault indications that were provided to the flightcrew• send a signal to illuminate a local fault light on the overhead panel (ifapplicable)• send a message to the central maintenance system (CMS), which included themessage in maintenance reports such as the post-flight report (section 1.12.2)• record a fault message in the system’s BITE memory, which could be used insubsequent maintenance troubleshooting activities.34In general, some of the LRUs within a system actually contained the BITE and conducted the faultdetection, rather than the system as a whole.- 23 -
Page 1: ATSB TRANSPORT SAFETY REPORTAviatio
Page 4 and 5: Published by: Australian Transport
Page 6 and 7: 3 FACTUAL INFORMATION: AIR DATA INE
Page 9 and 10: DOCUMENT RETRIEVAL INFORMATIONRepor
Page 11: TERMINOLOGY USED IN THIS REPORTOccu
Page 14 and 15: CSMCSSCVRDADSDCDGACDMCDMUEASAECAMED
Page 16 and 17: RAMRTCASATCOMSAESAOSDSECSEESEUSSASS
Page 18 and 19: FCPC design limitationAOA is a crit
Page 20 and 21: - xviii -
Page 22 and 23: associated with a master caution ch
Page 24 and 25: Figure 2: Aircraft track and key ev
Page 26 and 27: The crew decided that they needed t
Page 28 and 29: 1.3 Damage to aircraftThere was sig
Page 30 and 31: • The flight crew provided inputs
Page 32 and 33: exceeding a predefined safe flight
Page 34 and 35: Table 1: Examples of ADIRU flight d
Page 36 and 37: Inertial reference partThe IR part
Page 38 and 39: ADIRS switching controlsIn normal o
Page 40 and 41: Processing by ADIRUs and FCPCsEach
Page 44 and 45: A system could flag its output data
Page 46 and 47: Table 4: Summary of indications for
Page 48 and 49: Figure 17: ECAM engine / warning di
Page 50 and 51: Table 6: Required actions associate
Page 52 and 53: For internal aircraft communication
Page 54 and 55: Table 7: Sequence of events (from t
Page 56 and 57: In summary, the source of most of t
Page 58 and 59: Summary of IR data for the occurren
Page 60 and 61: Figure 22: QAR plot showing oscilla
Page 62 and 63: QAR dataOverall, the QAR recorded 4
Page 64 and 65: Flight crew pitch inputsDuring manu
Page 66 and 67: They provided information for maint
Page 68 and 69: Table 11: Cockpit effect messages d
Page 70 and 71: Table 13: Troubleshooting data rela
Page 72 and 73: position 1 on QPA. Further details
Page 74 and 75: class 1 fault messages shown in Tab
Page 76 and 77: If there was a discrepancy between
Page 78 and 79: 1.15 Survival aspectsInformation on
Page 80 and 81: did not identify any faults. The BI
Page 82 and 83: Comparison of the three occurrences
Page 84 and 85: 1.17.2 Processes for reporting and
Page 87 and 88: 2 FACTUAL INFORMATION: ELECTRICAL F
Page 89 and 90: monitored external systems that pro
Page 91 and 92: 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
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2.2.2 Review of recorded flight con
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second PRIM 3 FAULT. The role of ma
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The ACJ was built around the princi
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• It stated that the identificati
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The second part of the V-cycle invo
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• Functional requirements. These
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2.4.5 Safety assessment activitiesG
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equipment software and aircraft ins
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2.5.4 Factors associated with the i
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it is very difficult if not impossi
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applicable to highly-integrated or
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Ongoing developmentsA range of rese
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To conduct an effective fault tree
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According to this model, accidents
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3 FACTUAL INFORMATION: AIR DATA INE
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• inertial reference input/output
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3.3 Examination of data-spike patte
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Figure 38: ARINC 429 word for an AO
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3.3.4 Data-spike patterns for the 7
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Figure 43: Qualitative correlation
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etween the values of any of the fou
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3.4.3 Calculating parameter valuesA
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3.4.5 Packaging the ARINC 429 wordT
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3.4.8 Transmitting data to other sy
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ARINC 429 packaging analysisThe ADI
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component configurations of differe
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manufacturer reported such BITE dat
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3.6 Potential trigger types3.6.1 Ba
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such as liquids or small loose frag
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wires). The electric 144 field stre
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Although the investigation could no
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3.6.6 Single event effectsBackgroun
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until a few years ago, were not dir
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Unit testingIn 2005, as part of the
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that involved a NAV IR and/or NAV A
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EMI from other aircraft systems (su
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from ADIRU 1 was not correctly reco
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• Detected failure. Any failure w
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The ADIRU manufacturer’s analysis
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the aircraft and ADIRU manufacturer
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4 FACTUAL INFORMATION: CABIN SAFETY
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Summary details of the cabin crew
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section, and the ninth flight atten
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Table 29: Significant cabin communi
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Figure 48: Example of damage to the
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4.3.2 Seat belt examinationsSix pas
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The flight crew’s procedures requ
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takeoff, landing or when the seat-b
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Table 31: Levels of injuryInjury le
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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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- 231 -
Page 253 and 254:
- 233 -
Page 255 and 256:
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
Page 269 and 270:
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’
Page 294 and 295:
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
Page 313:
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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