AAIB urges tank control and monitoring changes after Virgin Atlantic aircraft suffers in-flight engine flame-out
UK safety investigators have urged Airbus to modify the A340-500/600's automatic fuel control and monitoring system in the wake of an emergency diversion to Amsterdam by a Virgin Atlantic crew when one of their aircraft's four engines flamed out and another faltered.
The UK Air Accidents Investigation Branch (AAIB) issued a Special Bulletin (SB) after its initial study of the event and says it will now conduct a full inspector's investigation into "this serious incident".
Two days after the 8 February event Virgin Atlantic instructed its A340-600 pilots to more closely monitor the wing inner fuel tanks – from which the engines are fed directly – and to initiate manual fuel transfer from other tanks if their contents reduce below 1,500kg (3,300lb). Airbus followed that up on 15 February with a flight operation telex advising airlines their crews should check the electronic centralised aircraft monitor (ECAM) fuel page every 30min, and providing details of actions required if automatic fuel transfer is lost.
As a flight progresses, the fuel management computers normally transfer fuel automatically from the centre-wing tank and from the trim tank in the tailplane to replenish the inner wing tanks that feed the engines directly, but in the Virgin incident this process had stopped without specific warning to the crew (see graph). Engines Nos 1 and 4 were affected by fuel exhaustion first because the wing tanks feeding them are smaller than those feeding 2 and 3, which still contained nearly 2,500kg each at their lowest point.
When the A340 had entered Dutch airspace en route from Hong Kong to London Heathrow, the No 1 engine lost power, according to the AAIB SB. The crew decided to continue to Heathrow on three engines, but soon the No 4 engine power began fluctuating. After the No 1 engine loss the crew had noticed that the inner 1 fuel tank was reading empty, so when No 4 began fluctuating they checked the Inner 4 tank and found it also reading empty – but the normal low-fuel warnings had not activated. The commander opened all fuel crossfeed valves, and No 4 engine recovered, but the crew declared a "mayday" and requested diversion to Amsterdam.
DAVID LEARMOUNT/LONDON
Source: Flight International
