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

Occurrence on 27 December 2008OverviewOn 27 December 2008, an Airbus A330-303 aircraft, registered VH-QPG (QPG)and being operated as Qantas flight 71, was on a scheduled passenger transportservice from Perth to Singapore. The aircraft departed Perth at 0750 UTC(1550 local time) and reached its cruise altitude of FL360 at 0814. At 0829(1729 local time), ADIRU 1 failed.The flight crew reported that:• The autopilot (autopilot 1) disconnected and the ECAM started providing aseries of caution messages, including a NAV IR 1 FAULT.• They actioned the relevant operational procedure 204 by selecting theIR 1 pushbutton to OFF and the ADR 1 pushbutton to OFF, and both OFF lightsilluminated.• They continued to receive multiple ECAM messages, and those messages wereconstantly scrolling on the display. One of the ECAM messages was a NAV IR1 FAULT, and the recommended crew action was to switch the ATT HDGswitch to the CAPT ON 3 position. They completed this action, but it did notstop the ECAM messages.• They returned to Perth and conducted an uneventful landing. At no stage wasthere any effect on the aircraft’s flight controls.At the time that the autopilot disconnected, the aircraft was about 480 km (260 NM)north-west of Perth and about 650 km (350 NM) south of Learmonth (Figure 26).The PFR for the 27 December 2008 flight contained a series of messages associatedwith ADIRU 1 that were very similar to those for the PFR from the 7 October2008 occurrence (Table D1). Consistent with there being no in-flight upset, therewere no PRIM FAULTS or PRIM PITCH FAULTS.Flight recordersThe flight data recording system fitted to QPG on 27 December 2008 differed fromthe system fitted to QPA. QPG had a single box system (Teledyne FDIMU partnumber 2234340-02-02) with two separate processors to handle both the FDR andACMS (QAR) functions. However, the source of ADIRU parameters for the FDRand QAR was the same as for QPA (section 1.11).The overall pattern of ADR and IR data from the recorders was very similar to thatfor the 7 October 2008 event. A summary of key events from the FDR is presentedin Table D2. The FDR data is presented in Figure D1 and D2, and QAR data ispresented in Figure D3.204This procedure was different to that which applied at the time of the 7 October 2008 occurrence.The relevant procedure at the time of the 27 December 2008 occurrence was based on AirbusOperations Engineering Bulletin (OEB) 74-3 issued in December 2008 in response to the7 October 2008 accident (section 7.1.1).- 237 -