Ned wrote:

BA 777 crash inquiry believes icing behind fuel-flow restriction
By David Kaminski-Morrow

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.