The Air Accidents Investigation Branch said in a statement Saturday that it was clear that the damage to the Ethiopian Airlines plane was far from the area where the carrier's batteries are located.
"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 agency said in a statement.
Investors in Boeing, which calls the plane a Dreamliner, had feared that Friday's fire meant that the battery problem that had grounded the whole fleet of such planes in January had not been fixed.
The incident did not cause any injuries because no one was aboard the plane, but it forced runways at Heathrow, one of the world's busiest airports, to shut down for nearly an hour.
U.S. investigators with the National Transportation Safety Board are assisting the AAIB in the investigation into the Ethiopian 787 fire. The U.S. Federal Aviation Administration and Boeing also have sent officials to assist in London.
The Heathrow fire appears to have been in “a very complicated area of the structure that ties together the fuselage barrel, the tail cone and vertical fin loads,” Robert Mann, an aviation consultant in Port Washington, New York, said in an e-mail. “It will be a complicated repair -- if it is repairable. I think every current and prospective operator will be looking at the outcome.”
An Ethiopian Airlines official said Saturday that the 787 fire was "not related to flight safety."
“We have to wait for the investigation,” Henok Teferra, head of corporate communications at Ethiopian Airlines in Addis Ababa, the capital, said in a text message. “At this point all that we can say is that there was no flight safety issue and the aircraft was parked for hours, waiting for the scheduled return flight time, when smoke was observed.”
The airline hasn’t grounded its three other 787s, the company said today in an e-mailed statement.
The FAA grounded the Dreamliner on Jan. 16 after the lithium-ion batteries overheated on two aircraft, with one catching fire in Boston with no passengers aboard. In that incident, a Japan Airlines Co. 787 experienced what U.S. safety investigators called an uncontrolled chain reaction that charred the battery. The second malfunction occurred on an All Nippon Airways plane that took off from Japan and was forced to make an emergency landing.
The FAA cleared the plastic-composite 787 to fly again after Boeing redesigned the battery to include more protection around individual cells to contain any overheating, a steel case to prevent fire and a tube to vent any vapors outside the fuselage.
Ethiopian Airlines on April 27 made the first Dreamliner flight after the grounding was lifted, traveling from Addis Ababa to Nairobi. The carrier has four 787s.
Through June, Boeing had delivered 66 Dreamliners to 11 airlines and a leasing company, including six to United Continental Holdings Inc. The 787 has a list price of $206.8 million.
“We will not speculate on the cause of this issue, but will closely monitor the findings,” said Mary Ryan, a spokeswoman for United Continental Holdings. It received six Dreamliners in 2012 and will get two this year, Ryan said.
The Japanese carrier ANA has taken delivery of 20 Dreamliners, the most of any airline, and was the first to receive the plane, in September 2011, according to Boeing’s website.
Ryosei Nomura, a spokesman for ANA, said in a phone interview that the company was aware of “what happened to the Ethiopian Airlines aircraft, but we are still confirming the details. We are collecting information via Boeing. As of now, the 20 787 jets we own are all in their regular operation.”
While Boeing officials maintain the 787’s reliability is on par with the Boeing 777 at this stage in its development, some industry watchers disagree.
“I’m hard-pressed to find any other aircraft to come into service with this level of conspicuous problems,” said Richard Aboulafia, vice president at Teal Group, an aerospace consultant based in Fairfax, Virginia. The 777 also had operational glitches and teething problems, “but there weren’t flames,” he said.