Boeing crash: 'No evidence of mechanical defect'

An investigation into the British Airways' Boeing 777 that crash-landed at Heathrow airport last month has found "no evidence" of a mechanical defect.

A report by the Air Accidents Investigation Branch (AAIB) said that the data from the flight recording systems indicated there were "no anomalies in the major aircraft systems."

It also concluded: "The autopilot and the autothrottle systems behaved correctly and the engine control systems were providing the correct commands prior to, during and after the reduction in thrust.

"Examination of the engines indicated no evidence of a mechanical defect or ingestion of birds or ice".

The Boeing 777 had 136 passengers and 16 crew on board the flight which was traveling from Beijing to London on January 17.

The cockpit crew were unable to get the required thrust from the engines as the plane came into land and the aircraft was forced to come down on the grass "some 1,000ft short of the paved runway surface and just inside the airfield boundary fence", the report said.

Samples taken from the fuel tanks showed that there were "no signs of contamination or unusual levels of water content".

Regarding the high pressure pumps, the report said: "Detailed examination of both the left and right engine high pressure fuel pumps revealed signs of abnormal cavitation (air bubbles) on the pressure-side bearings and the outlet ports.

"This could be indicative of either a restriction in the fuel supply to the pumps or excessive aeration of the fuel. The manufacturer (Boeing) assessed both pumps as still being capable of delivering full fuel flow."

The relevance of small items of debris found in the fuel tanks are also "still being considered".

The report went on to make a safety recommendation concerning the order in which the captain Peter Burkill and first officer John Coward had gone through the evacuation checklist procedures.

Boeing had raised no technical objection to BA introducing a save-time checklist sequence but the report concluded this had led to a loss of fuel from the aircraft.

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

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