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

2006, see below). During the investigation, a third event was reported on 27December 2008 (see below).The aircraft manufacturer conducted searches of the PFRs from a significantproportion of Airbus aircraft flights to identify any PFRs with a similar set ofmessages as were recorded during the three known occurrences. No other eventswere identified. Further details of these searches are provided in Appendix D.The aircraft and the ADIRU manufacturers advised that they were not aware of anyother occurrence involving similar anomalous ADIRU behaviour. They alsoadvised that, if such a problem had occurred and no fault was found in a subsequentground test of the unit, then the event would probably not be reported to them.Communications by the operator and ADIRU manufacturer with other A330operators since 7 October 2008 also did not identify any similar occurrences.Another ADIRU manufacturer also advised that it was not aware of any similartypes of events.12 September 2006 data-spike occurrenceThe 12 September 2006 occurrence involved the same aircraft (QPA) and the sameADIRU (4167) as the 7 October 2008 occurrence. No recorded data was availablefor that flight other than the PFR. However, the PFR and the flight crew’sdescription of numerous warning and caution messages provided sufficientevidence to conclude that the occurrence involved similar ADIRU data outputanomalies as that which occurred on the 7 October 2008 flight. Following the 2006flight, line testing of the ADIRU was conducted in accordance with themanufacturer’s procedures; no fault was found and the aircraft was returned toservice.Further details of the 2006 occurrence are provided in Appendix D.27 December 2008 data-spike occurrenceThe 27 December 2008 occurrence involved another of the operator’s A330-303aircraft, registered VH-QPG (QPG), and a different LTN-101 ADIRU (serialnumber 4122). In that occurrence, the crew reported receiving numerous cautionmessages and that the messages on the ECAM were constantly changing. The crewfollowed a new procedure that was introduced after the 7 October 2008 occurrence,which was successful in shutting down the ADR part 28 seconds after the failuremode started (and 24 seconds after the autopilot disconnected). The new procedurewas not effective in shutting down the IR part. 71The FDR and QAR data showed evidence of data spikes on all IR parameters andsome of the ADR parameters (in the 28 seconds during which it operated in thefailure mode). General observations about the spike timing and magnitudes weresimilar to those for the 7 October 2008 event. In addition to data spikes, the IR datafor the 27 December 2008 event also showed similar patterns as the IR data on the7 October 2008 flight.ADIRU 4122 was removed from the aircraft and sent to the manufacturer’sfacilities for examination and testing and to download the BITE data. The testing71Following the 27 December 2008 occurrence, the procedure was modified further to eliminate thisproblem (section 7.1.1).- 59 -