On 24 February 2011 and 3 November 2011 respectively, two different Airbus A380-842 (A380) aircraft were being operated by Qantas Airlines on scheduled passenger services from Singapore to London, United Kingdom.
About 8 hours into the flight on 24 February 2011, the flight crew detected a reduction in the indicated oil tank quantity for the No 3 engine. The crew reduced the thrust on the affected engine to idle and continued to the planned destination. Maintenance personnel found that one of the engine's external oil feed pipes was finger tight and had leaked. This was the fourth event involving similar in-flight oil loss from engines installed on the operator's fleet of A380 aircraft.
Examination and testing by the engine manufacturer found that the oil leaks were the result of a loss of clamping force on the oil feed pipe connection at the engine casing. Potential factors in the loss of clamping force were identified and were subject to ongoing engineering analysis. In the interim, the aircraft operator checked the engine oil feed pipes every five flight cycles, then every 20 cycles for evidence of oil leakage.
On 3 November 2011, a different aircraft was about 3 hours into the flight when the flight crew received a low oil quantity advisory for the No 4 engine. Forty minutes later, the crew received a low oil pressure warning from that engine. The crew shut down the engine and diverted the aircraft to Dubai, United Arab Emirates. Maintenance personnel found that one of the engine's oil feed pipes had leaked in the same location as the earlier A380 engine oil loss events.
By the time the November event occurred, there had been 15 engine oil leaks across the A380 fleet worldwide. The engine manufacturer conducted an ongoing investigation into the oil leaks and at the time of writing this report had identified high pipe deflection loads as a significant factor. Subsequent action by the engine manufacturer included modification of the oil pipe clipping arrangement and revised securing methods for the pipe connection and deflector assembly. In addition, trend monitoring of engine oil consumption was enhanced and work continued to develop a new oil pipe design.