Jet engine gave clues prior to breakdown

4 problems reported, most with turbines, oil

A passenger waited to board a Qantas jet yesterday in Sydney. The Rolls-Royce Trent 900 is a technologically advanced engine in 20 Airbus A380s around the world. A passenger waited to board a Qantas jet yesterday in Sydney. The Rolls-Royce Trent 900 is a technologically advanced engine in 20 Airbus A380s around the world. (Tim Wimborne/Reuters)
By Michael Weissenstein and Joan Lowy
Associated Press / November 12, 2010

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LONDON — Rolls-Royce engines on the world’s largest airliner malfunctioned four times before one of them disintegrated during flight last week, and aviation specialists said yesterday that the earlier mishaps might hold clues to design or construction flaws.

Four problems dating to 2008 led to two warnings for airlines to check parts of the Rolls-Royce Trent 900, a technologically advanced model used by 20 Airbus A380s around the world.

Three of the four previous problems centered on the turbines or oil system. An oil leak is suspected in last week’s disintegration, and since then several A380s have been grounded after oil leaks or stains were discovered in another six Trent 900 engines.

The number of problems identified in the Trent 900 is not unusual for a jet engine, and analysts, pilots, and former safety investigators caution that there is no obvious link between the earlier mishaps and last week’s failure.

But they also said they suspect there may be critical problems that were not detected before the engine went into use. Several identified the tubes that pump oil around the spinning turbines of the house-size engine as a possible culprit.

Based on what authorities have said, it appears the problem with the Trent 900 is a “fundamental unforeseen flaw’’ that will probably be expensive to fix, said Michael Barr, who teaches aviation safety at the University of Southern California.

Joerg Handwerg, a spokesman for the pilots union for German airline Lufthansa, said minor problems are routine for any jet engine, but it is possible the issues are an indication that regulators did not adequately check the engine before approving it for commercial use.

Barr said the Trent 900 is “out there right at the edge of the envelope’’ of new engines that are lighter, more efficient, less polluting, and less noisy.

“The engine has been out there for a few years; they’ve got some miles on it, and now they’re finding things they didn’t foresee,’’ he said.

The European air-safety regulator pointed to the oil system as a culprit in last week’s mishap, saying yesterday that leaking oil may have caught fire in the Qantas Trent 900 that disintegrated and sent pieces slicing through vital control systems in the wing.

The disintegration on the Qantas A380 was more serious than the airline implied, said John Goglia, a former member of the US National Transportation Safety Board and an airline maintenance expert.

Damage from engine shrapnel to the wing over the engine occurred very close to the wing’s front spar, one of two support beams that attach the wing to the plane, he said. If the shrapnel had hit the spar it could have weakened the spar and even caused the wing to fall off, he said.

Photos and video of the mishap show the shrapnel ruptured a hydraulic line and an electric line in the wing, cutting off the pilots’ control of half the brake flaps and the remaining engine on the affected wing, along with the door of the landing-gear compartment, Handwerg said. “It’s not a single failure, it’s a multiple failure. That obviously creates a more risky situation,’’ he said.