UK investigators believe that ice was the source of the fuel-system restriction which led a British Airways Boeing 777-200ER to experience a loss of engine power on approach to London Heathrow in January, and crash just short of the runway.
In an interim report on the accident today, the Air Accidents Investigation Branch has issued three safety recommendations, including one directed specifically at Rolls-Royce Trent 800-powered 777s.
The AAIB is recommending that US and European regulators - in conjunction with Rolls-Royce and Boeing - introduce "interim measures" to reduce the risk of restriction in Trent-equipped 777 fuel-feed systems caused by icing of water in fuel.
Flight BA038 from Beijing crashed short of Heathrow's runway 27L on 17 January. All 152 passengers and crew survived the accident but the aircraft suffered severe damage.
AAIB attention has focused on the external conditions during the flight, particularly given that the Trent-powered aircraft passed through areas of extremely cold air while in cruise.
"The investigation has shown that the fuel flow to both engines was restricted, most probably due to ice within the fuel-feed system," says the AAIB. "The ice is likely to have formed from water that occurred naturally in the fuel while the aircraft operated for a long period, with low fuel flows, in an unusually cold environment."
It stresses, however, that the 777 was being operated within its certified operational environment the whole time.
US FAA and European Aviation Safety Agency regulators should take "immediate action to consider the implications" of the inquiry's findings on other aircraft, says the AAIB.
It also recommends that both authorities review certification requirements to ensure aircraft and engines are "tolerant" to the build-up and possible sudden release of ice in their fuel-feed systems.
- AirSpace gallery of images from the incident involving a BA 777
- Flight's safety and operations editor David Learmount's blog Learmount - 777 crash at Heathrow: what chance of another such accident?
Source: Air Transport Intelligence news