An interim ATSB investigation report has confirmed that a Rolls-Royce engine manufacturing defect ultimately led to the 4 November 2010 uncontained engine failure on board a Qantas A380 aircraft over Batam Island, Indonesia.

The report released yesterday explains how the intermediate pressure turbine disc in the aircraft's No. 2 engine had been weakened by an oil fire. As a result, the disc separated from its shaft, increased its rotation speed and broke into several parts. Sections of the fractured disc and other engine components penetrated the aircraft's left wing and a number of other areas on the aircraft, resulting in significant structural and systems damage.

The oil fire that weakened the disc was due to a manufacturing defect in an oil feed pipe. That defect resulted in fatigue cracking in the pipe, so that oil sprayed into an engine cavity where it ignited because of the high air temperature.

The report also shows how some of the extensive flight data recovered in the first stage of the investigation has been used to program a simulation of how the aircraft handled following the accident. This has helped investigators to understand better the aircraft's handling and performance.

The simulation was part of a broader exercise to understand the extent and consequences of the airframe and systems damage to the aircraft
and the consequences for flight crew workload. The findings from this continuing work will provide valuable safety lessons for future operations.

The ATSB said it will continue to work with international safety agencies and other organisations to gather and compile the large amount of complex factual information required to complete the investigation. Given the highly complex nature of this investigation, the final ATSB report is expected to be released in May 2012.

Meanwhile, the aircraft is currently in Singapore awaiting repair.