B-777 Cold Weather AD Issued

The FAA has issued an airworthiness directive affecting Rolls-Royce RB211 Trent 800-powered Boeing 777-200/300 jetliners that are operated in extremely cold temperatures. 
The AD requires revision of the aircraft flight manual to include in-flight procedures for pilots to follow in certain cold weather conditions and requires fuel circulation procedures on the ground when certain conditions exist. The AD results from an incident of uncommanded reduction in thrust on both engines because of reduced fuel flow. “We are issuing this AD to prevent ice from accumulating in the main tank fuel feed system, which, when released, could result in a restriction in the engine fuel system. Such a restriction could result in failure to achieve a commanded thrust, and consequent forced landing of the airplane,” stated the FAA. On Jan. 17, a British Airways Boeing 777-200 equipped with Rolls-Royce RB211 TRENT 895-17 turbofans crash landed short of a runway at London Heathrow. During final approach, the autothrottles commanded an increase in thrust from both engines, and the engines initially responded. However, at a height of about 720 feet above the ground, the thrust of the right engine reduced, and seven seconds later, the thrust on the left engine also reduced.