Source: ATW Daily News Author: 05/22/2008
Subject Concerned: Government Airlines Plane Crash Aviation Fuel
Investigation into the Jan. 17 crash landing of a British Airways 777 on final approach to London Heathrow has not revealed an anomaly that could have caused the flow of fuel to the engines to be reduced as the pilots called for more power, according to the UK Air Accident Investigations Branch, although restricted fuel flow was certainly the cause of the non-fatal accident.
In an update released on May 21, AAIB noted that the engine control system detected the reduced flow and "commanded the fuel metering valve to open fully." The valve responded, "but with no appreciable change in the fuel flow to either engine." Some kind of "restriction" in the fuel system between the fuel tanks and the pumps is suspected.
Examination of the aircraft and analysis of recorded data "have revealed no evidence of an aircraft or engine control system malfunction," nor is there any evidence of "a wake vortex encounter, a bird strike or core engine icing. There is no evidence of any anomalous behavior of any of the aircraft or engine systems that suggests electromagnetic interference. The fuel has been tested extensively; it is of good quality, in many respects exceeding the appropriate specification, and shows no evidence of contamination or excessive water. Detailed examination of the fuel system and pipe work has found no unusual deterioration or physical blockages."
Investigators are examining whether "particularly" cold temperatures along the flight path may have had something to do with the restriction, although the temperatures "were not exceptional" and tests revealed that the fuel onboard had a measured freezing temperature of -57C, well below the minimum recorded lowest fuel temperature of -34C.