There is no evidence at this stage of a link between a fire that broke out on a Boeing Dreamliner parked at London's Heathrow airport and the plane's batteries, Britain's Air Accidents Investigation Branch (AAIB) said on Saturday.
The fire broke out on the plane, operated by Ethiopian Airlines, on Friday afternoon, when it was parked at a remote stand with no passengers on board, eight hours after arriving from Addis Ababa. No one was injured.
The question of whether the fire was in any way connected to the batteries is crucial because the entire global fleet of Dreamliners, Boeing's new flagship jet, was grounded for three months this year due to battery-related problems.
"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."
Separately, Britain's Thomson Airways said one of its Dreamliners that had to turn back during a flight on Friday had suffered a "minor technical issue".
Thomson said a small number of components had been replaced, the aircraft had been fully tested and it would take off from Manchester in northwest England bound for Cancun in Mexico at 9:50 a.m. (0850 GMT/ 4:50 a.m. EDT) on Sunday.
Thomson declined to specify which components had been replaced. The aircraft turned back as a precautionary measure during a flight from Manchester to Sanford in Florida on Friday afternoon.
Thomson said its two other Dreamliners had also been fully tested and would fly from London's Gatwick airport to Sanford and to Palma on Sunday.
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.
Boeing shares closed down 4.7 percent at $101.87 on Friday, knocking $3.8 billion off the company's market capitalization.
"SMOKE THROUGHOUT FUSELAGE"
The Ethiopian Airlines Dreamliner has been moved to a hangar at Heathrow where it is under technical investigation, the AAIB said, adding that the initial witness and physical evidence showed there had been smoke throughout the fuselage.
The AAIB said the U.S. National Transportation Safety Board (NTSB), 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 U.S. Federal Aviation Administration, Boeing, Ethiopian Airlines, the European Aviation Safety Agency and Britain's Civil Aviation Authority to participate as advisers to the investigation.
Boeing will be keen to reassure airlines, travelers and investors over the cause of the fire as quickly as possible but under aviation rules it will be up to investigators to decide how much information to release and when.
Ethiopian Airlines, one of Africa's top five carriers, said it would continue to fly its Dreamliner fleet. It has ordered a total of 10 Dreamliners, of which four have been delivered.
"The incident at Heathrow happened while the plane was on the ground and had been for more than eight hours and was not related to flight safety," the carrier said in an emailed statement on Saturday.
"After a normal flight from Addis to London, passengers disembarked in the morning and the aircraft was cleaned. It was towed to a remote parking area as usual and parked properly with all internal and external powers switched off," said an official from the airline's public relations department.