The Australian Transport Safety Bureau (ATSB) has released its final report into the uncontained engine failure involving a Qantas A380 over Batam Island, Indonesia on 4 November 2010, finding the failure was the result of a fatigue crack in an oil feed-pipe in the number two Rolls-Royce Trent 900 of the aircraft.
“The crack allowed the release of oil that resulted in an internal oil fire,” the ATSB report noted. “The oil fire led to one of the engine’s turbine discs separating from the drive shaft. The disc then over-accelerated and broke apart, bursting through the engine casing and releasing other high-energy debris.”
The accident occurred about four minutes after takeoff from Singapore. At about 7,000ft above Batam Island, the engine failure sent debris into the aircraft’s left wing and fuselage, and onto Batam Island.
The aircraft sustained damage from a large number of disc fragments and associated debris. The damage affected the aircraft’s structure and a number of its systems. The ATSB found a large fragment of the turbine disc penetrated the left wing leading edge before passing through the front spar into the left inner fuel tank and exiting through the top skin of the wing. The fragment initiated a short duration low intensity flash fire inside the wing fuel tank. The ATSB determined that the conditions within the tank were not suitable to sustain the fire.
Another fire was found to have occurred within the lower cowl of the No. 2 engine as a result of oil leaking into the cowl from the damaged oil supply pipe. The fire lasted for a short time and self-extinguished.
The large fragment of the turbine disc also severed wiring looms inside the wing leading edge that connected to the aircraft’s electrical, hydraulic and other systems. The crew managed the multitude of system failures before safely returning and landing the aircraft, the report stated.
Rolls-Royce has supported the conclusions of the ATSB report.
Colin Smith, Director Engineering & Technology, Rolls-Royce said: “This was a serious and rare event which we very much regret. 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. The robustness of the Airbus A380 and the professionalism of the Qantas crew members assured that the aircraft and all its passengers landed safely.
“We support the ATSB’s conclusions and, as the report notes, have already applied the lessons learned throughout our engineering, manufacturing and quality assurance procedures to prevent this type of event from happening again.”
Rolls-Royce noted the oil pipe was one of a small number which had been incorrectly manufactured as a result of a measurement error during a precision drilling procedure.
Following the incident and in parallel with the ATSB’s investigation, Rolls-Royce carried out its own investigations to understand and address the chain of events which led to faulty oil pipes being released into service. A number of issues were identified and changes implemented to address them, including:
- Modification of the engine software to prevent a turbine disc from bursting as a result of over-speeding following a similar failure.
- Better quality assurance processes with supporting training.
- Revised analysis of the likely effects on an engine in the event of a component failure.
- Improved manufacturing and design procedures.
Following the uncontained failure, the ATSB, Rolls-Royce, regulatory authorities and A380 operators using Trent 900 engines took a range of steps to ensure that those with non-conforming oil feed stub pipes were identified and either removed from service or managed to ensure their safe continued operation. Rolls-Royce also released an engine control software update that included a turbine overspeed protection system designed to shut the engine down before the turbine disc can overspeed, in the unlikely event that a similar failure occurs.
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