What happened
During a flight from Sydney, NSW, to Kuala Lumpur, Malaysia, the right engine (engine 2) of an Airbus A330 operated by AirAsia X experienced a sudden loss of oil pressure. The failure originated in the oil pressure pump drive shaft, which caused the pressure in the engine to drop rapidly to 0 psi. The aircraft's electronic centralised aircraft monitor (ECAM) triggered an ENG 2 OIL LO PR alert, notifying the flight crew of the issue.
Following the alert, the crew reduced the thrust on engine 2 to idle. Although the established procedures suggested a shutdown, the crew chose to monitor the engine's performance instead. After approximately four minutes, the crew moved the thrust lever back to the normal inflight position. This increase in thrust caused the engine to surge multiple times before it ultimately failed. The crew then performed the engine failure procedure, shut down the engine, and diverted the aircraft to Melbourne.
The investigation
Investigators examined the sequence of events following the oil pressure alert, the crew's decision to monitor the engine rather than shut it down, and the subsequent attempts to relight the engine. The crew attempted to restart engine 2 twice: once shortly after the initial failure and a second time just before descending into Melbourne.
An analysis by Rolls Royce identified that the drive shaft had failed due to fatigue cracking. This specific type of failure was noted as an unusual occurrence that had not been previously documented.