CONCERNS over the future of Rolls-Royce powered A380s have taken a new turn after three of Singapore Airlines' superjumbos were grounded.

A spokeswoman for the airline has confirmed that the planes, currently grounded in Melbourne, Sydney and London, will be flown back to Singapore without passengers.

Up to 24 technical and cabin personnel will be onboard the jets, which will fly for at least five hours and up to 11 hours each to reach Singapore where they will undergo engine changes.

"It's not that it's not safe, it's that we are taking precautionary measures by changing three engines on these planes," the spokeswoman said.

Rolls Royce advised the airline to take action after tests showed signs of oil stains in the engines, she said.

Earlier today crew in Heathrow refused to fly an A380 jet bound for Singapore after oil was allegedly found in one of the turbines, Heraldsun.com.au reports, a claim Singapore airlines says is "absolutely incorrect".

The forced grounding came about at about the same time as another A380 owned by the same airline left Sydney for Singapore.

First reports suggest that passengers who were due to depart from London were told that engine-maker Rolls-Royce had placed an embargo on its now-suspect Trent 900 engine which was designed for the A380, the world's biggest airliner.

Rolls Royce spokesman Roger Hunt said checks are being carried out on affected A380 planes but could not confirm if an embargo was in place.

"This is a process of ongoing checks. Safety is our highest priority," Mr Hunt said.

On Monday, Singapore Airlines said inspections had found no problems with the Rolls-Royce Trent 900 engines used on the carrier's Airbus A380s.

"We completed engine inspections on all 11 of our A380 aircraft and did not find anything of concern," the airline's spokesman Nicholas Ionides said in a statement.

"Any further checks that may be recommended by the manufacturers will of course be done, and in the meantime we continue with our regular routine checks."

The airline has warned that passengers due to leave Sydney for Singapore this afternoon may face disruptions as the airline seeks to accommodate them on other flights.

Passengers flying from Melbourne to Singapore were delayed for a few hours this morning before being accommodated on an alternative aircraft.

The grounding comes after Qantas said last night it had cleared the backlog caused by the grounding of its A380 fleet.

New reports have emerged that allege the spectacular engine failure near Singapore last week caused more damage to the plane involved than first thought.

The No 2 engine's violent disintegration ripped a hole through the Airbus A380's left wing, destroying wiring that prevented the pilots from turning off the No 1 engine and causing a fuel leak.

Suggestions have now emerged that there was also significant damage to hydraulic systems that prevented spoilers, panels on the wing that create drag to slow the plane down, from deploying.

The suggestions came as the Australian Transport Safety Bureau yesterday interviewed the flight crew of the stricken A380 and performed the first boroscope inspection of the Rolls-Royce Trent 900 engine.

Investigators are continuing their search for the rest of a turbine disc that broke up in the incident and have set up a schedule for examining a recovered piece that has been sent to Britain for forensic tests.

Inspections of the grounded planes continued yesterday amid suggestions European regulators were poised to issue an airworthiness directive on the checks.

Qantas is using its Boeing 747s and Airbus A330s to plug the gap caused by the A380 groundings and says it will be able to keep operations going and meet network requirements while the A380 issue is resolved.

Mr Joyce said Rolls-Royce had a good understanding of the problem, which was likely to result in a series of recommendations.

The engine-maker broke its silence to say it had made progress in understanding the cause of the engine failure on QF32 but did not provide details.

Rolls-Royce rejected speculation there was a link between the Trent 900 failure and the uncontained failure of a Boeing 787 Trent 1000 engine operating "outside of normal parameters" on a test bed in Britain.

Singapore Airlines, Qantas and Lufthansa operate A380 jets powered by different versions of the Trent 900 engine series.

The model fitted to the six Qantas planes is more powerful than that used by Singapore and Lufthansa, producing 72,000 pounds of thrust.

- with Steve Creedy and Kate Schneider

