Qantas extended the grounding of its Airbus A380 superjumbos for at least three more days on Monday after finding oil leaks in some engines, heightening safety fears after two mid-air blow-outs last week.
However Singapore Airlines said Monday its inspections of its 11 A380 superjumbos had found no problems with their Rolls-Royce Trent 900 engines, as it continues flying the planes.
In Sydney, Qantas chief executive Alan Joyce said rigorous testing had uncovered the anomalies on the Rolls-Royce engines on three separate aircraft, pushing back the return to action of the long-haul planes by 72 hours.
"The oil leaks were beyond normal tolerances," Joyce told journalists. "All of these engines are new engines.
"At this stage, Qantas does not expect to operate the A380 fleet for at least another 72 hours."
Qantas\' impeccable safety record -- the Australian flag-carrier has never had a fatal jet crash in 90 years -- has come under the spotlight after two engine explosions in as many days last week.
On Thursday, a Qantas Airbus A380 was forced to return to Singapore for an emergency landing after one of its four Rolls-Royce Trent 900 engines exploded just minutes into its flight, showering an Indonesian town with debris.
And on Friday, a Qantas Boeing 747 -- which was carrying the A380\'s captain -- also had to turn back to Singapore after another model of Rolls-Royce engine also failed in mid-air.
Both flights, which were carrying a combined total of 897 passengers and crew, arrived safely back in Singapore but some of those onboard have spoken of their fear at hearing blasts as the engines failed.
"I just looked at my wife and held hands and I really thought I was going to die," New Zealander Hamzah Munif said of his experience on the Boeing 747-400 after returning to Sydney on Sunday.
But Swedish passenger Peter Geisler said he was not frightened by the malfunction which he described as "no big deal" given the aircraft was able to operate on its three other engines.
"I didn\'t hear any riots or people crying or anything," he told reporters.
Qantas\'s six A380s, the world\'s biggest commercial jet, service lucrative routes from Los Angeles and London to Australia\'s major cities of Sydney and Melbourne.
The grounding has forced the carrier -- which has refused to speculate on the cost of the operation -- to add extra services on some routes and use other aircraft to allow thousands of passengers to make their journeys.
Joyce said Qantas\'s A380s would not take to the skies until the airline was "100 percent sure that we can assure the safety of our operations".
"We are not going to take any risks whatsoever," he told reporters.
Qantas said last week an engine design flaw on the double-decker planes may be at fault, and Joyce said the oil leaks would help narrow investigations into the blast, which also caused damage to the wing and one other engine.
It was possible "this is a problem with the engine not meeting its design criteria", he said.
News of the extended grounding came as Japan\'s low-cost carrier Skymark Airlines said it will buy four A380 superjumbos from Airbus, with an option on two more, in a deal worth about 2.8 billion dollars.
Joyce said Qantas, the only airline which is still grounding its A380s, took safety "unbelievably seriously" but he still expected the massive aircraft to be flying again within days.
"We still believe with the progress we are making -- this is days not weeks -- but we will take as long as it needs to in order that we are absolutely comfortable the aircraft is safe to fly," he told ABC Radio.
The incidents have overshadowed Qantas\'s anniversary celebrations which started on Saturday, with visiting "ambassador-at-large" and trained pilot John Travolta forced to defend the airline\'s safety record.
The Hollywood star said Qantas\' pilot training was arduous "and that\'s why you guys are so safe."
Shares in the "Flying Kangaroo" shed 2.1 percent to 2.80 Australian dollars.
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