The engine failure that caused the emergency landing of a Qantas Airbus A380 in Singapore may have been caused by a design fault, the Australian airline says.
"We believe this is most likely some kind of material failure or a design issue," CEO Alan Joyce said, adding the investigation was continuing.
One of the engines failed after take-off from Singapore's Changi airport.
Qantas has grounded its six A380 jets pending emergency checks.
Mr Joyce said it was too early to say what exactly caused the problem, but he said the blowout was "an engine issue" and not one of maintenance on the two-year-old plane.
The incident occurred on Thursday, when flight Qantas QF32 experienced an engine failure over western Indonesia, before safely returning to Changi airport. It was carrying 440 passengers and 26 crew.
It was the most serious incident involving the twin-deck A380 superjumbo passenger plane in its three years of service.
British jet engine maker Rolls-Royce said it was checking all the A380s in service - with Qantas, Singapore and Lufthansa - that use its Trent 900 engines.
The other A380 aircraft - with Air France and Emirates - use a different engine.
A statement on the Rolls-Royce website said it had "well established" processes to collect and understand information relating to the event and to "determine suitable actions".
It said safety was the number one priority, adding: "We continue to work closely with our customers as the investigation moves forward. This is at a very early stage and it would be inappropriate to drawn any conclusions at this time."
On Friday, Singapore Airlines said it had completed the checks and was resuming its A380 flights.
The European Aviation Safety Agency confirmed it had issued an airworthiness directive on 4 August requiring an inspection of certain conditions within the Trent 900 engine.
Thursday's aborted Qantas flight from Singapore was bound for Sydney. Passengers were put on a relief flight to Australia early on Friday.