Qantas has said that faulty engine design or material failure were the most likely causes of an engine blow-out on one of its Airbus A380 superjumbos.
The airline also confirmed that pieces from the engine had pierced the plane's wing.
Qantas chief executive Alan Joyce said it was too early to say exactly what caused one of the plane's four engines, supplied by Rolls-Royce, to fail shortly after take-off from Singapore and that a thorough investigation was under way.
But he said maintenance, for which the airline has responsibility, did not appear to be a significant factor.
"This is an engine issue and the engines have been maintained by Rolls-Royce since they were installed on the aircraft," Joyce said.
"We believe this is probably most likely a material failure or some type of design issue. We don't believe this is related to maintenance in any way."
A row broke out between Qantas and the Australian Licenced Aircraft Engineers’ Association today after the federal secretary of the organisation, Steve Purvinas, claimed that Qantas engineers had been stood down following the A380 incident. Qantas’ Joyce said Purvinas was peddling “prejudices and generalisations” about aircraft maintenance when it was too early to speculate on the cause of the engine failure.
The A380 suffered an engine blow-out about four minutes after taking off from Singapore on Thursday, shooting flames and shedding metal over an Indonesian island. It landed safely in Singapore after dumping its fuel.
It was the most serious mid-air incident involving the double-decker A380, the world's largest passenger jet, since it debuted in October 2007 with a Singapore Airlines flight to Sydney.
Airbus said it had asked all airlines operating A380s with Rolls-Royce engines to inspect them to ensure safety.
Airbus has delivered a total of 37 A380s so far. Thirteen are in service with Emirates, 11 with Singapore Airlines, six with Qantas, four with Air France and three with Lufthansa.
Qantas’ fleet of A380s remains grounded. Singapore Airlines, which also grounded its A380s after the Qantas incident, said it had resumed flights after completing precautionary checks.
Lufthansa said it was still conducting inspections but expected to be able to fly an A380 from Frankfurt to Tokyo as scheduled today. It held back an A380 yesterday for checks and instead flew an A340-600 on a flight from Frankfurt to Johannesburg, said the airline.
Emirates airline said all of its A380s were flying as scheduled. Its planes are not powered by Rolls-Royce engines.
Joyce said Qantas would complete its checks within two days, and if no problems were found the planes would resume flying.
Talking of the damage to the wing caused by the incident, he said: "Parts of the engine did go into the wing of the aircraft... that was part of what made this a significant engine failure."
The engine closest to the fuselage on the left wing had visible burn marks and was missing a plate section painted with the red kangaroo logo of the airline. The upper part of the left wing had raised and torn metal.
Ian Sangston, general manager of air safety investigation at the Australian Transport Safety Bureau, said the faulty engine was being removed for inspection and the rest of the plane was also being examined.
The flight data and cockpit voice recorders had been recovered and brought to Australia, where their contents would be analysed.