ATSB moves into final stage of QF32 investigations

Singapore
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Australian investigators have finished collecting data for an investigation into the uncontained failure of a Rolls-Royce Trent 900 engine on a Qantas Airways A380 on 4 November 2010.

The data is being analysed and a final investigation report is expected in the third quarter of 2012.

Both Rolls-Royce and Airbus have taken several measures to improve their processes, said the Australian Transport Safety Bureau (ATSB) in an interim report released on Thursday.

The engine-maker conducted several "major internal investigations" looking into the manufacture of oil pipes with reduced wall thickness, the management of concessions of manufactured components, and the failure mode, effects and criticality analysis (FMECA) of previous component failures.

Rolls-Royce has revised its procedures to include feature checks and risk assessment during the design and manufacture of new structures, and introduced a revised procedure to provide training to better manage the application of retrospective manufacturing concessions.

In its FMECA procedures, Rolls-Royce has revised it to include numerical justifications for any assumptions made.

Meanwhile, Airbus is working with airports and firefighting agencies to develop an agreed safe method for these agencies to externally shut down the manufacturer's engines when the need arises.

The agreed procedure will then be incorporated into Airbus's rescue and firefighting chart and distributed to those involved.

In its report, the ATSB said together with the Air Accidents Investigation Branch of the UK and Rolls-Royce, it is still looking into "the circumstances and missed opportunities with the potential to have detected the reduced wall thickness and offset counter bore of the oil feed pipe" before, during and after the manufacturing of the IP turbine module case.

The ATSB added that checks on the airframe and systems damage has been completed and did not reveal any significant or critical safety issues.

So far, the investigations identified a defect in an oil feed tube as the cause behind an oil fire, which led to the engine failure.

The defect caused a section of the oil tube to thin out and crack, leading to an internal engine oil fire that weakened the intermediate pressure turbine disc. This was then separated from the turbine shaft, puncturing the engine case and wing structure.

The ATSB will now move into the analysis of the "complex factual information" that has been gathered.

The A380 involved in the incident is still undergoing repairs in Singapore and is expected to return to service in March.