Initial Boeing Fire Probe to Take Days: WSJ

Global airlines continued to fly Boeing Co. 787 Dreamliners as investigators probed the cause of a fire that seriously damaged one of the advanced jets while it was parked at London's Heathrow Airport.

Friday's incident, which occurred when the Ethiopian Airlines plane was empty, has revived significant uncertainty for Boeing and the 13 airlines currently operating the Dreamliner, which have labored to rebuild trust in the wide-body plane since problems with its lithium-ion batteries triggered a three-and-a-half month grounding of the global 787 fleet in January.

Investigators have said little so far, beyond a short statement Saturday by the U.K. Air Accidents Investigation Branch saying there was no evidence the batteries directly caused the fire. The statement was good news for Boeing, which has said its fixes to the battery system would protect against further fires.

But the statement left open a range of possibilities that could have varying impact on the jet's future, such as some sort of isolated human error or a new design flaw in the Dreamliner's advanced electrical system, which is one of the 787's signature innovations. Boeing's shares closed down 4.7% on Friday after news of the incident at Heathrow.

The Air Accidents Investigation Branch, which is leading the probe with assistance from U.S. officials, said the initial investigation is likely to take several days. Boeing said Saturday that it was asked to participate as an adviser to the inquiry and added: "Protocol dictates that all publicly released information concerning the investigation must come from, or be approved by, the AAIB."

A company spokesman said Sunday, "The safety of passengers and crew members who fly aboard Boeing airplanes is our highest priority. We are confident the 787 is safe and we stand behind its overall integrity."

The airlines' decision to continue Dreamliner flights suggested there was no immediate evidence of a widespread systemic problem that could endanger passengers. Ethiopian said the incident was "not related to flight safety," though a person familiar with the situation later said that referred simply to the fact that the plane wasn't flying at the time. Ethiopian said it hasn't grounded its three other Dreamliners. Several carriers—including United Continental Holdings Inc., the only U.S. operator of the 787, and All Nippon Airways Co. and Japan Airlines Co., the two largest 787 operators—said they were monitoring the investigation closely and wouldn't speculate on the cause.

Thomson Airways Ltd., which had one of its 787s turn back to the U.K.'s Manchester airport on Friday in an unrelated incident that the airline attributed to "technical issues," said Saturday it had replaced some components on that plane and that all three of its Dreamliners were flying as scheduled. "We want to reassure our customers that we have every confidence in this aircraft and would never operate it if we weren't 100% sure of its safety," the carrier said.

The Ethiopian 787, which had arrived from Addis Ababa, was parked at Heathrow for more than eight hours before smoke was detected onboard. Calling it a "serious incident," the Air Accidents Investigation Branch said the fire caused "extensive heat damage in the upper portion of the rear fuselage" and spread smoke throughout the fuselage. Television images show it burned through the plane's carbon-fiber composite skin on its roof, in front of the tail fin.

Safety experts said it is premature to draw conclusions. But two people briefed on early parts of the probe said preliminary indications suggest the fire was in the overhead area over the last few rows of seats. The plane was plugged into ground power while parked, though it isn't clear whether its power was on.

Boeing has been reviewing systems near the rear of the jet that would remain powered by the attached ground power supplied by the airport, said one of the people briefed on early parts of the probe. What those systems are couldn't immediately be determined. Among the electrical parts installed near the area of the fire are two of the plane's 17 remote power-distribution units, which act as substations for the 787's electrical system, and three of the 21 remote data concentrators, which help distribute data signals to systems from the jet's central computer.

Those solid-state components are part of the Dreamliner's powerful electrical and computer systems, which Boeing designed to replace many traditional mechanical parts and wiring to make the plane lighter and burn less fuel. Like its batteries, the 787's electrical grid and central computer system rely on technologies that haven't been used before in jetliners.

A spokesman for GE Aviation, a unit of General Electric Co. that supplies the data concentrators, said "we are not aware that GE components are part of the investigation." A spokesman for United Technologies Aerospace Systems, a unit of United Technologies Corp. that provides the power-distribution units said, "we have not been asked to participate in any investigation on the Heathrow incident."

Another person familiar with but not directly involved in the probe said investigators are examining parts that also are used on jets made by the Airbus unit of European Aeronautic Defence & Space Co.  The data concentrators are installed inside Airbus A350 and A380 aircraft. Airbus declined to comment.

Airlines also continued to fly Dreamliners immediately after a Jan. 7 battery fire on a Japan Airlines Co. 787 parked at Boston Logan International Airport. A burning battery on an All Nippon Airways Co. 787 nine days later, which forced an emergency landing, triggered the world-wide grounding.

In those incidents, the batteries were immediately and publicly identified as the source of the issue. Japanese carriers were moving to voluntarily ground Dreamliners until the battery systems were analyzed and permanently fixed, industry officials said at the time. That pressured the Federal Aviation Administration to act quickly and aggressively by ordering all U.S.-registered 787s to stay on the ground. Within hours of the Jan. 16 order, other governments followed the FAA's lead, not wanting the political liability of keeping 787s in service contrary to FAA mandates.

Without investigators determining a clear-cut cause for the Ethiopian incident so far—and with other 787 operators continuing to keep their Dreamliners in the air—this time the FAA appears to be under less pressure to announce immediate action.

In Washington, the decision-makers also have changed. Anthony Foxx, a former mayor of Charlotte, N.C., was recently confirmed as transportation secretary, and industry officials describe his management style as less hands-on than that of his predecessor, Ray LaHood. Mr. LaHood's initial reaction to the 787 battery fire in Boston was to personally vouch for the safety of the aircraft, while ordering FAA officials to launch a broad review of the certification process used to approve its entry into service. After the second incident, Mr. LaHood and FAA chief Michael Huerta quickly ordered the grounding.

Teams of FAA safety experts have basically completed their internal review of the 787's certification, according to agency officials, and many of their findings were sent to the FAA's senior leadership around the end of June. The review teams, among other things, visited various Boeing 787 subcontractors to assess quality-control procedures.

Now, Messrs. Huerta and Foxx must decide when and how to release the review's conclusions and recommendations. The FAA has said in the past that the certification report's findings are likely to be released this summer. The agency declined further comment on Sunday.