Investigation Still Centering On Oil Feed Pipe In Rolls-Royce Trent 900 Engine

The ATSB has released an interim report in its investigation of an uncontained engine failure which occurred on a Qantas A380 flying from Singapore to Sydney. The engine failure caused the pilot to return to Singapore, as well as the grounding of Qantas' A380 fleet in November of 2010.

The investigation team is being led by the Australian Transport Safety Bureau (ATSB). With the assistance of accredited representatives from the Bureau d'Enquêtes et d'Analyses (BEA), the Air Accidents Investigation Branch of the United Kingdom (UK AAIB), the Air Accident Investigation Bureau of Singapore (AAIB Singapore), the National Transportation Safety Committee of Indonesia (NTSC), and advisors to those investigation bodies including Rolls-Royce, Airbus, SAFRAN Sagem, Honeywell (USA and UK), Aerolec UK and Singapore Aero Engine Services Private Limited, the data gathering phase of the investigation is complete and the team has commenced analysing that data.

During the period July to August 2011, accredited representatives from the BEA and UK AAIB and advisors from Airbus met with ATSB investigators in Canberra, Australia to ratify relevant A380 technical data in respect of the structural and systems damage sustained by the aircraft as a result of the uncontained engine failure. The examination of relevant Rolls-Royce Trent 900 engine data and a number of engine manufacturing processes is nearing completion.

The ATSB has met with Rolls-Royce and Qantas Airways to update those parties on the progress of the investigation. In accordance with international protocol and ATSB policy and procedures, those and other relevant stakeholders will be involved in the development of the investigation findings and final report.

In conjunction with the UK AAIB and Rolls-Royce, the ATSB is continuing its examination of the circumstances and missed opportunities with the potential to have detected the reduced wall thickness and offset counter bore of the oil feed pipe prior to, during and after the manufacture of the module 51 assemblies. The ATSB has also reviewed the quality audits undertaken, and quality assurance system affecting the module 51 design and manufacturing process, and their effectiveness in detecting deficiencies in that process.

In the interim, Rolls-Royce has conducted a number of major internal investigations into its processes including the manufacture of oil pipes with reduced wall thickness, management of retrospective concessions of manufactured components, and failure mode, effects and criticality analysis (FMECA) of previous component failures.

As a result of those investigations, Rolls-Royce has revised procedures for new structures that include feature verification and risk assessment during the design and manufacture process, as well as introducing a revised, standalone procedure with appropriate supporting training to better manage the application of retrospective manufacturing concessions, and revised its FMECA procedures to provide 'best practice' numerical justification for any assumptions made.

The investigation will monitor the progress of those initiatives.

The examination of airframe and systems damage that resulted from the engine disc burst has been completed. That examination did not reveal any significant or critical safety issues. The continuing repair of the aircraft in Singapore has allowed the examination of relevant removed/replaced aircraft components at the ATSB's technical facilities in Canberra. Those components have included a number of wiring looms, elements of the aircraft's airframe and a number of sub-components.

As part of its ongoing examination of this event, Airbus has commenced working with a number of airport and rescue and firefighting agencies to develop an agreed safe means for those agencies to externally shut down engines on Airbus aircraft - as became necessary in this case. Any agreed procedures will be incorporated in the Airbus Aircraft Rescue and Fire Fighting Chart and be made available to airports and fire crews on line in document and poster form.

The investigation is continuing and has progressed to the analysis of the large amount of complex factual information that has been gathered during the investigation. The drafting of the investigation report has commenced and will include extensive liaison with domestic and international stakeholders. In accordance with international protocol, that will include a 60-day consultation period for international parties to the investigation.

The final report is anticipated for public release in the third quarter of 2012. (Images provided by ATSB)

FMI: www.atsb.gov.au