Qantas A380 QF32 : défaillance moteur à Singapour

Update 19 January 2012
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
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
introduced a revised, standalone procedure with appropriate supporting training to better manage the application of retrospective manufacturing concessions
revised its FMECA procedures to provide 'best practice' numerical justification for any assumptions made.
The investigation will monitor the progress of those initiatives.
Aircraft response to the disc failure
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.
Airbus proactive safety action
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.
Ongoing investigation activities
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.
The information contained in this web update is released in accordance with section 25 of the Transport Safety Investigation Act 2003 and is derived from the initial investigation of the occurrence. Readers are cautioned that new evidence will become available as the investigation progresses that will enhance the ATSB's understanding of the accident as outlined in this web update. As such, no analysis or findings are included in this update.

Repairs to the Qantas Airways Airbus A380 that had an uncontained engine failure in November 2010 added only 94kg to the weight of the aircraft.

This was far less than originally anticipated, says Airbus, with the airframer and Australia's flag carrier agreeing at the start of the project that the "weight impact" of the repairs would not exceed 250kg.

Earlier reports by Flightglobal Pro had put the additional weight at 200kg, but Airbus clarifies that the actual weight added to the aircraft was far less at 94kg.

"This was achieved due to 'as-new' replacement parts being used wherever possible. This very small additional weight impact was a considerable achievement," adds Airbus.

The overall performance of the aircraft, including its range and efficiency, is unlikely to be affected by the additional weight, says Airbus.

The aircraft, which has the registration VH-OQA, had a mid-air uncontained engine failure after take-off from Singapore in November 2010. Repairs were completed in April, and the aircraft returned to Sydney on 22 April.

Australian investigators have finished collecting data for an investigation into the uncontained failure of the Rolls-Royce Trent 900 engine. The data is being analysed and a final report is expected in the third quarter of 2012.

Australian safety regulators have issued a final report on the Qantas A380 engine failure and emergency landing on Nov. 4, 2010, including more details about the incident and a review of manufacturing failings at engine-maker Rolls-Royce.
The incident saw flight QF32 return to Singapore’s Changi Airport shortly after takeoff due to an uncontained failure in one of its Trent 900 engines. The cause has already been traced to an oil fire in the engine, resulting from a cracked oil feed pipe in the high pressure/intermediate pressure (HP/IP) hub assembly. The wall width of some oil feed pipes –including the one that cracked on the Qantas aircraft – was found to be thinner than design specifications due to a misaligned bore.
The Australian Transport Safety Bureau (ATSB) says in its final report that the crack in the oil pipe resulted from fatigue, and “developed over some time.” The crack became wide enough to allow oil to be released into the buffer space between the bearing chamber and the hot air surrounding the IP turbine disc. The oil was released as an atomized spray, and the air within the buffer space was hot enough for the oil to ignite.
The resulting fire eventually affected the IP turbine disc drive arm, resulting in the separation of the disc from the drive shaft. “Following the separation of the disc, the engine behaved in a manner different to that anticipated by the manufacturer during engine design and testing,” the ATSB says. The disc accelerated to a speed “in excess of its structural capacity” and burst into three main segments, which punctured the engine case.
Regarding Rolls-Royce, the ATSB found that the misalignment of the counter bores in the feed pipes “was the result of movement within the HP/IP bearing support assembly during manufacture and that a number of opportunities existed during the design and manufacture processes where the misaligned oil feed stub pipe counter bores could have been identified and managed.” According to the final report, “those opportunities were missed for a number of reasons, but generally because of ambiguities within the manufacturer’s procedures and the non-adherence by a number of the manufacturing staff to those procedures.”
The factors that led to the mistakes occurred over a number of years, and “highlighted the importance of manufacturers providing clear procedures and of personnel complying with those procedures,” the ATSB says. The safety agency says it has worked with the aircraft and engine manufacturers “to ensure that any identified safety issues were addressed and actions taken to prevent a similar occurrence.”
Responding to the final report, Rolls-Royce says it “supports the conclusions” of the ATSB. “This was a serious and rare event which we very much regret,” says Colin Smith, the manufacturer’s director for engineering and technology. “At Rolls-Royce we continually strive to meet the high standards of safety, quality and reliability that our customers and their passengers are entitled to expect. On this occasion we clearly fell short.”
Smith says Rolls-Royce has “already applied the lessons learned throughout our engineering, manufacturing and quality assurance procedures to prevent this type of event from happening again.” The company says it has also carried out its own investigations to understand and address what went wrong.
Specifically, the engine-maker says it has modified engine software to prevent a turbine disc from bursting due to over-speeding. It has also introduced better quality assurance processes with supporting training, improved manufacturing and design procedures, and revised the analysis of “the likely effects on an engine in the event of a component failure.”