DAVID LEARMONT / LONDON AND BRIAN DUNN / MONTREAL
Engine maintenance spotlighted in first ever engines-out landing of a fly-by-wire aircraft
A maintenance error appears to have caused the 24 August incident in which an Air Transat Airbus A330-200 ran out of fuel and had to make an engines-out landing at Lajes air base in the mid-Atlantic Portuguese Azores islands.
The Canadian charter carrier's flight 236 was cruising at 39,000ft (11,900m) with 291 passengers and 13 crew en route from Toronto, Canada, to Lisbon, Portugal, when the starboard engine stopped. Minutes later the port engine quit. The Portuguese investigators say that both engines failed "as a result of fuel starvation".
Airbus has contacted all A330 operators, especially those with Rolls-Royce Trent 772-211E engines like Air Transat, to advise them to carry out "precautionary checks" on the engine low pressure fuel feed pipe inside the engine cowling. R-R says that the damage consisted of a 75mm (3in) crack. Airbus says that it was caused by "interference with a hydraulic pipe from the rear hydraulic pump". An R-R modification, notified to operators in a March 1999 service bulletin (SB), was designed to prevent this, but the Airbus telex says that the SB "appears to have been partially applied on the affected engine".
Meanwhile, investigators are looking at how long Capt Robert Piche and First Officer Dirk DeJager knew about the fuel problem, and why they appeared to have taken no action to isolate the leak.
The leak was downstream of the starboard engine low pressure fuel cut-off valve, according to the Airbus bulletin. If the pilots had shut this, it would have closed down the right engine but stopped the fuel loss. The flight could then have continued with the left engine only. The location of the fuel leak, however, may not have been clear to the crew. Nevertheless, shutting the fuel crossfeed valve between the left and right wing tanks would have secured the fuel in the left wing tanks.
DeJager says that when he checked the fuel at 04:57 there was sufficient to continue to Lisbon. At 05:25, an hour before fuel exhaustion, he first reported a fuel problem and requested a diversion to Lajes. He declared an emergency 23min later, and at 06:13 radioed air traffic control saying the right engine had failed. Around 13min later, at 32,000ft and with 100nm (185km) to go to Lajes' runway, the left engine stopped. The crew prepared the aircraft for ditching, but 20min later, landed the A330 heavily but safely at Lajes.
Daniel Verrault, director of air investigations at the Transportation Safety Board of Canada, says a fuel leak should not cause a two-engine shutdown.
Airbus says that the information so far has not indicated a design or manufacturing problem with the aircraft. Transport Canada is auditing Air Transat's maintenance records, and has reduced its 120min extended range twin engine operating authority to 60min. This restricts its twin-engined aircraft to routes within 60min single engine flying time from usable diversion airports.
Source: Flight International