Ruled Out Ice, Water, And Contamination Of Fuel Tanks

The BBC reports investigators have ruled out ice, water or contamination of fuel tanks on a Boeing 777 that was forced to land short of a runway at London Heathrow Airport on January 17. The Air Accidents Investigation Branch is quoted as saying the plane's data recorder showed nothing wrong with major aircraft systems.

There was some damage to the fuel pumps, and what were termed small items of debris found in the fuel tanks. Investigators have also ruled out bird ingestion by the engines as the cause of a failure by the engines to produce enough power to reach the runway on landing.

There were 136 passengers and 16 crew members on the plane. All survived, although a few were injured, and some have claimed trauma of various types on the British Airways flight from Beijing.

The board did note the aircraft climbed into areas with lower than average temperatures over the Urals and Eastern Scandinavia, with outside ambient temperatures reaching as low -76ºC. However, the Board noted that resulted in a total air temperature (TAT) of "only" -45 degrees C, and the minimum recorded fuel temperature was -34 degrees C... quite chilly, but still comfortably above the -57ºC freezing point of the fuel onboard.

While the investigation continues, BBC reports investigators have issued one recommendation -- that Boeing should notify all Boeing 777 operators to operate the fuel control switch to cut-off prior to operation of the fire handle, to reduce the risk of fuel leaks as seen in the aftermath of the Heathrow accident. Fortunately, while fuel leaked from the 777 as its undercarriage was damaged, the fuel did not ignite.

The AAIB also believes an evacuation checklist created by British Airways to save time over the procedures recommended by Boeing left passengers exposed to risks from fire.

"This was not causal to the accident but could have had serious consequences in the event of a fire during the evacuation," said the AAIB report.

Boeing reportedly did not find fault with the BA version of the checklist, but the board suggests Boeing make clear its own checklist should be followed in future evacuations.

FMI: Download The AAIB Update (.pdf)