TRANSPORT investigators say an oil leak caused the engine of a Qantas A380 flight to explode last month.
The Sydney-bound flight was traveling over Indonesia on November 4 when it was forced to return to Singapore after the failure of one of its Rolls-Royce-built Trent 900 engines.
The incident was the result of "an uncontained engine failure'', which saw a loose disc shear through the left wing and other parts of the aircraft, resulting in structural and systems damage.
"The initial assessment was that the most likely cause of the engine failure was problems with the release of oil into a particular part of the engine, leading to an oil fire and consequences finally in the liberation of the disc elements,'' Australian Transport Safety Bureau chief commissioner Martin Dolan said.
"That was initially responded to by ensuring there were regular inspections for oil leakages in the ... engine in the Airbus 380.
"And on that basis with caution continued operations were seen as acceptable.''
Mr Dolan said there had been extra checks over the past 48 hours involving Rolls Royce, which led to an official safety recommendation yesterday.
"(We) determined there was a particular problem that at that stage not been identified and we therefore yesterday issued a safety recommendation in relation to that issue, which was essentially ... potential manufacturing defects in oil pipes in a number of Trent 900 series engines, which have the potential to lead to fatigue, cracking, the liberation of oil and the sort of things that happened in the incident over Batam Island.''
The report also outlines a number of areas for further investigation including additional examination of the turbine disc and other engine components, onboard recorded information, damage to the aircraft and its systems, and of the response by flight, cabin and emergency services crews.
Qantas grounded its entire A380 fleet after the incident and says that sixteen engines require either modification to the latest standard or full replacement. Five of these have already been replaced.
It had recently returned two planes to the skies but was forced to conduct one-off inspections on both the aircraft following the safety warning. The first plane has since resumed service and inspection of the second aircraft has commenced.
The airline said that no issues outlined by air safety investigators have been found and the first plane will operate to London via Singapore tonight as scheduled.
Qantas will continue to operate a full international and domestic schedule and expects to announce the return to service of more A380s before Christmas.
“After discussions with the Australian Transport and Safety Bureau (ATSB) and Rolls-Royce, it was decided it was prudent to conduct further inspections of engine components, although there is no immediate risk to flight safety,” Qantas said.
Mr Dolan said it was impossible to say how close QF32 came to disaster following the explosion.
But the chief commissioner said when pieces of an engine turbine were released "the consequences are very serious".
"The most serious damage (to QF32) in terms of scale was the result of one significant part of the turbine disc going directly through the wing of the aircraft," Mr Dolan said.
There was also damage to wiring in the wing.
As a result, the slats of the aircraft couldn't be deployed for landing and there were "limitations" on the information the crew received regarding nose-wheel steering.
Turbine fragments flew out of the QF32’s engine when it exploded in mid-air last month, severing cables in the wing, narrowly missing the fuel tank and taking out flight control systems, a preliminary report by Airbus found.
The pilots were forced to deal with an "unprecedented" number of issues during the two-hour ordeal, Vice President of the Australian and International Pilots Association, Richard Woodward, said.
The airline has been granted an injunction by the Federal Court of Australia to sue Rolls-Royce over the losses it suffered due to the A380 engine issues.
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