The British Airways Boeing 777-200ER which crash landed at London Heathrow on 17 January had adequate fuel on board and that both engines continued to generate thrust, albeit much-reduced, say investigators.
Preliminary findings from the UK Air Accidents Investigation Branch had indicated that the twinjet's Rolls-Royce Trent 800 engines had failed to respond to an auto-throttle command for increased thrust during the final stage of the approach.
In an update issued last week, however, the AAIB says both engines did initially respond to the auto-throttle command, but that the starboard engine's thrust reduced after about 3s and the port engine's thrust also reduced to a similar level 8s later.
"The engines did not shut down and both engines continued to produce thrust at an engine speed above flight-idle, but less than the commanded thrust," it adds.
Data from the flight recorders, says the AAIB, shows that an "adequate" fuel quantity was on board the twin-jet and that both the auto-throttle and engine-control commands were performing as expected, both before and after the thrust reduction.
"All possible scenarios that could explain the thrust reduction and continued lack of response of the engines to throttle-lever inputs are being examined," it adds.
It states that the analysis includes examination of the fuel-flow path between the 777's fuel tanks and the engine fuel nozzles.
All 136 passengers and 16 crew members on board the aircraft (G-YMMM) escaped with only a handful of minor injuries after the aircraft, operating flight BA038 from Beijing, suffered heavy damage after landing short of Heathrow's runway 27L.
Keep up to date on the latest developments in the BA 777 investigation at http://www.flightglobal.com/ba777