SYDNEY (AP) - The investigation of the engine failure that grounded Qantas' fleet of superjumbo jets is making progress, manufacturer Rolls-Royce said Monday, while the airline announced that tests uncovered worrying oil leaks in the engines of three more Airbus 380s.
Australia's national carrier said its fleet of six doubledecker planes would stay grounded for another 72 hours.
Airbus and other airlines said they would take no action until the investigation is completed, and that it was premature to contemplate any change from the Rolls-Royce Trent 900 engines mounted on many of the A380s - the world's largest passenger jet.
Meanwhile, a European aviation official said the engine's design features had prevented a worse tragedy from occurring after it blew up.
Rolls-Royce Group PLC stock rose more than 2 percent on the London Stock Exchange after the company issued a brief statement saying the tests were "being progressively completed." It said the problem had been isolated to its Trent 900 family of high-bypass fan engines, but provided no further details on how long the inspections would take. Shares in Rolls-Royce Group were down 8 percent Friday.
An engine on a Qantas Airbus 380 exploded minutes into a flight from Singapore to Sydney on Thursday, scattering debris over Indonesia's Batam island. The plane, carrying 466 people, returned to Singapore and made a safe emergency landing.
The version of Rolls-Royce Trent 900 engine used by Qantas differs slightly from those installed on the A380s of other airlines - Lufthansa and Singapore Airlines - because it is a little more powerful.
The Australian Transport Safety Bureau, which is leading an international investigation of the incident, has appealed for help to find a missing piece of a turbine disc, saying it may be crucial evidence needed to fully understand what caused the engine to burst.
The agency released a photo of a jagged and bent piece of turbine disc from the Trent 900 and asked that anyone finding a similar piece should give it to police.
The photos appeared to indicate a failure of the metal disc at the center of the jet turbine. These spin at speeds of 12,000 rotations per minute at high power settings during takeoff and the initial climb, generating immense centrifugal forces.