Air accident investigators continued on Sunday to try to figure out why a parked 787 Dreamliner caught fire on Friday in London, while airlines around the world kept flying the plane and expressed confidence in it.

Passengers and investors in Boeing, the Chicago-based plane maker, were left to make their own calculations about how serious the problem would turn out to be.

In that sense, the situation seemed like a return to the limbo of early January, after a battery fire broke out on a Dreamliner parked in Boston and federal safety officials began an investigation. Only after a battery started smoking on another 787 days later were regulators compelled to ground the planes worldwide for four months.

Now, the latest episode raises its own puzzling question: Is the innovative jet passing through mere growing pains, or is there a more serious problem in its design or manufacturing?

Investigators in London have essentially put to rest any concerns about a repeat of the battery hazards. But it is still not clear whether the fire on the Ethiopian Airlines 787, which sat unoccupied in a remote spot at Heathrow Airport, was caused by something as simple as a galley stove that had been left on or a faulty component, or indicated a more serious problem.

Several of the 13 airlines flying the plane, including Ethiopian, and several that have ordered the planes, including Virgin Atlantic, said they were confident in Boeing and were sticking with the Dreamliner. Some frequent fliers and passenger-rights groups, however, were more skeptical.

“What do we tell consumers? ‘Flier beware,’ ” said Kate Hanni, the founder of FlyersRights.org, an airline passenger advocacy group.

Ms. Hanni, a real estate broker in Napa, Calif., said she was personally concerned because she and her husband were scheduled to fly to Tokyo on the Dreamliner in mid-August. Depending on the outcome of the investigation into the fire at Heathrow, she said, she might ask to fly on a different aircraft.

“I am very nervous about it,” she said. But, she added, “so far the Dreamliner appears to be safe while in flight.”

United Airlines, the only United States carrier that is flying the 787 so far, said on Sunday that it had not made any changes to its 787 flight schedule as a result of the fire. “We won’t speculate on the cause but will closely monitor the findings of the investigation,” it said in a statement. British Airways reiterated that it planned to start its Dreamliner service on Sept. 1.

Several airlines also said they had been in close touch with Boeing, which has sent a team to London to support the British investigators. Boeing said in a statement that the safety of passengers and crew members was “our highest priority.” It added: “We are confident the 787 is safe and we stand behind its overall integrity.”

Still, unless the cause of the Heathrow fire is pinpointed quickly, Boeing, the airlines and the Federal Aviation Administration could once again find themselves in a delicate spot in balancing passenger safety with high financial stakes, including millions in lost revenue that would come from any delays or suspensions in service.

Boeing and its suppliers have invested more than $20 billion in the Dreamliner, which uses lightweight carbon materials and more efficient engines to cut operating costs by some 20 percent. The company has delivered 68 of the planes to the 13 airlines, and it expects to sell thousands of the planes over the next two decades.

The F.A.A. and the National Transportation Safety Board, which investigates aircraft safety issues, are assisting the Air Accidents Investigation Branch in Britain with the Heathrow inquiry. Federal officials said the F.A.A. typically needs to have more information about what went wrong — and indications that the problems apply to more than one aircraft — before it takes any action.

Former federal safety officials said that so far they were not picking up the kind of urgent alarms about the Heathrow fire from current safety officials as they did after the Boston battery fire. Aviation consultants said the airlines were also not quite sure what to make of the problem, in part because Ethiopian Airlines workers could have made a mistake in doing maintenance on the plane.

Natasha Singer, Georgi Kantchev and Stephen Castle contributed reporting.

Article source: http://www.nytimes.com/2013/07/15/business/airlines-confident-in-boeings-787-but-doubts-linger.html?partner=rss&emc=rss