Sydney: Dramatic mid-air engine failures that struck two Qantas aircraft in as many days are unrelated, the airline said, adding it was confident of the safety of the planes it is flying.
Qantas grounded its A380 superjumbos on Thursday after one carrying 466 passengers and crew was forced to return to Singapore after an engine exploded during ascent, raining debris onto an Indonesian island.
The 90-year-old airline suffered a second engine failure the following day when a Sydney-bound Boeing 747-400 jumbo carrying 412 passengers and 19 crew experienced problems shortly after take-off from Singapore.
Unlike the A380 engine blast -- which sent debris flying, causing damage to the plane`s wing -- the second incident was a "contained engine failure", Qantas chief executive Alan Joyce said.
"We are not concerned about our 747 fleet," he added. "Those engines have a long life... We`ve seen inflight shutdowns take place before... It`s... not a safety issue."
He pointed to mechanical failure as the source of the problem, which occurred six minutes into the flight, causing the engine to emit sparks and smoke and frightening passengers who likened the explosion to fireworks.
"It was pretty scary," said Swedish tourist Lisa Ogden, who was on board. "An engine on the wing exploded. It looked like fireworks, a pretty big one," she told reporters at the airport.
"The plane jumped a bit and the cabin crew were yelling `crisis` and they told everyone to sit down."
Asked whether he thought the 747 had been sabotaged, Joyce said: "We do not believe this is sabotage. It looks like a mechanical failure of the engine."
Joyce has also said an engine design fault may have caused the other mid-air emergency involving an Airbus A380 superjumbo.
Both planes landed safely in Singapore, with no injuries to any on board.
Qantas has said it will investigate both incidents, and that engine checks were still being carried out on the airline`s six A380s, which Joyce said he hoped to have back in use soon.
"We are hopeful that within days we will have our A380 fleet flying again," he said.
The airline has been using other aircraft to pick up passengers booked onto A380s -- the world`s biggest passenger jets -- but the problems have delayed hundreds of passengers in Los Angeles, London and Australia.
Among those delayed was the captain of the A380, Richard Champion de Crespigny -- praised by passengers for his calm handling of Thursday`s mid-air crisis -- who was on board the 747 which was forced back the following day.
Also on that plane were his two co-captains from the A380 flight, Qantas said.
The engine failures, which are front page news in Australia, were earlier described as "unrelated incidents" by Qantas spokeswoman Olivia Wirth.
Qantas said that while both aircraft operated on Rolls-Royce manufactured engines, the stricken Boeing 747-400 was fitted with Rolls-Royce RB-211 engines while the Qantas A380 uses Rolls-Royce Trent 900 engines.
A Qantas Boeing 747 engine failed on a flight from San Francisco to Sydney in August, blowing a hole in the engine casing and forcing an emergency landing. No one was injured in the incident.
The latest unexplained engine failures have overshadowed Qantas` birthday celebrations, which kicked off at Sydney airport on Saturday with a visit by the airline`s ambassador-at-large, Hollywood star John Travolta.
The actor, who flew his Boeing 707 aircraft to Sydney for the 90th birthday party, said he had had a fascination with aviation since he was five and had been intrigued by Qantas because it is the longest over-water carrier.
Qantas spokeswoman Wirth said that the airline had considered cancelling the celebrations, which were attended by thousands of Qantas staff, before deciding to go ahead. "You only turn 90 once," she said.
Qantas, known as the `Flying Kangaroo`, has never had a fatal jetliner crash.