Investigators classified the fire that broke out on a Boeing 787 Dreamliner parked at London’s Heathrow Airport as a “serious incident,” but have found no evidence it was caused by the plane’s batteries, Britain’s Air Accidents Investigation Branch (AAIB) said on Saturday.
The question of whether the fire was connected to the batteries is crucial because the entire global fleet of Dreamliners, Boeing’s groundbreaking new flagship jet, was grounded for three months this year because of battery-related problems.
The AAIB designation fell just short of a full-blown “accident” on the scale it uses to describe investigations. The agency’s preliminary probe is expected to take several days, opening up Boeing to more questions about its top-selling aircraft.
Despite the uncertainty surrounding the blaze, airlines around the world continued to operate the Dreamliner. Eighteen 787s took to the skies on Saturday afternoon, about the same number as on Friday.
The fire broke out on the Ethiopian Airlines plane on Friday afternoon, and was discovered when smoke was seen coming from the plane eight hours after its arrival from Addis Ababa. No one was injured.
“There has been extensive heat damage in the upper portion of the rear fuselage, a complex part of the aircraft, and the initial investigation is likely to take several days,” the AAIB said in a statement.
“However, it is clear that this heat damage is remote from the area in which the aircraft main and APU [Auxiliary Power Unit] batteries are located, and, at this stage, there is no evidence of a direct causal relationship,” it said.
Footage from the scene of the fire showed apparent scorching on the fuselage near the tail. The Dreamliner’s two batteries are in compartments located low down near the front and middle of the aircraft.
The Financial Times on Saturday reported that airline staff had discovered a problem with the aircraft’s air conditioning system during a routine inspection and had seen sparks, but no flames.
The Times, quoting Mark Mangooni, Ethiopian Airlines’ senior manager in Britain, did not make clear when this had happened.
Separately, Britain’s Thomson Airways said one of its Dreamliners that turned back during a flight from Manchester to Sanford, Florida on Friday had suffered a “minor technical issue” and had now had a small number of components replaced.
Thomson said the aircraft had been fully tested and was being taken back into service at once. The airline declined to specify which components had been replaced.
The Heathrow and Manchester incidents were a new blow for Boeing after the entire global fleet of Dreamliners had to be grounded for three months, ending in April, after one high-tech battery caught fire and another overheated.
Ethiopian Airlines said it would continue to fly its Dreamliner fleet. It has ordered a total of 10 Dreamliners, of which four have been delivered.
Several other airlines said they were continuing to operate their Dreamliners, including United Continental, the Polish airline LOT, Japan Airlines and ANA, the world’s biggest operator of the 787.
The AAIB said the US National Transportation Safety Board, representing the state of design and manufacture, and the Civil Aviation Authority of Ethiopia, representing the state of registry and operator, had been invited to appoint accredited representatives to participate in the investigation.
The AAIB also said it had also invited the US Federal Aviation Administration, Boeing, Ethiopian Airlines, the European Aviation Safety Agency and Britain’s Civil Aviation Authority to participate as advisers to the investigation.