The Australian Transport Safety Bureau was advised on 27 December 2008 of an occurrence that day involving a Qantas Airbus A330-300 aircraft while in cruise at FL360 (36,000 ft) enroute from Perth to Singapore.
At about 0829 UTC (1729 Local Time), the autopilot disconnected and the crew received an ECAM message (NAV IR 1 Fault) indicating a problem with ADIRU Number 1. The crew actioned the Airbus Operations Engineering Bulletin (OEB) procedure by selecting the IR 1 push-button to OFF and the ADR 1 push-button to OFF. Both OFF lights illuminated. The crew elected to return to Perth and an…