New Worries for Boeing 787 After Fire: WSJ

An unoccupied Ethiopian Airlines 787 Dreamliner caught fire while parked at London's Heathrow Airport, reprising worries over the Boeing Co. flagship jet three months after it resolved battery problems that had grounded it worldwide.

Emergency crews were called about 4:30 p.m. local time on Friday and soon extinguished the blaze. No one was injured in the incident, which prompted airport authorities to halt flights for more than an hour at Heathrow, the world's busiest international airport. Broadcast images showed that the fire, which authorities said started inside the plane, burned through a portion of the carbon-fiber skin on the top of the jet near the tail.

Officials had yet to determine the cause of the fire Friday evening. There was no indication that it was directly related to the Dreamliner's lithium-ion batteries, which are housed farther toward the front of the plane. Overheating of those batteries triggered burning on two 787s in mid-January that caused regulators to ground the jetliner.

Boeing developed a system to contain fire risk at the batteries, which the Federal Aviation Administration approved, enabling flights to resume in late April. Boeing's business has since been soaring, with deliveries in the latest quarter hitting their highest number in 15 years, including 17 new 787s. Boeing has delivered a total of 68 Dreamliners to 13 airlines around the world.

The incident hit Boeing shares, which had risen by more than 40% this year through Thursday despite the battery problems, knocking them as much as 7.4% lower before ending the day down 4.7% at $101.87 in Friday trading on the New York Stock Exchange.

Other airlines continued to fly their Dreamliners in the hours after the fire. A spokeswoman for United Continental Holdings Inc., UAL +1.95% which operates six 787s and is the only U.S. carrier to fly the plane, said it wouldn't speculated on the cause of Friday's fire "but will monitor the findings."

All Nippon Airways, a unit of ANA Holdings Inc. and the jet's largest operator, said its 20 787s are operating normally. A spokeswoman said the carrier was "still trying to figure out what happened" in the Heathrow incident.

The Dreamliner had been parked at Heathrow for roughly eight hours before the fire was detected, Ethiopian Airlines said. While attention is focused on the plane's systems, it is possible something else caused the blaze. Fires occur on parked planes about once every five years, said Paul Hayes, director of air safety at Ascend, a British aviation consulting firm. Causes have included short-circuits in lavatory electrical sockets, a rag left in a galley oven, and cigarettes. Mr. Hayes said several incidents were suspected to have started after a cleaner or ground worker furtively smoked on a parked plane and then failed to fully extinguish the cigarette.
 
In a statement released shortly after the incident, Boeing said it had "personnel on the ground at Heathrow and [we] are working to fully understand and address this." Ethiopian Airlines said "the cause of the incident is under investigation by all concerned."

The U.K. Air Accident Investigation Branch sent a team to investigate. The U.S. National Transportation Safety Board said it was sending an expert to the scene, and the Federal Aviation Administration said it would also send an official "in support of the NTSB."

As early reports and images of the fire streamed in, several industry and government safety experts said they were struck by its apparent intensity. The incident is likely to generate additional questions and discussion about the flame-resistant qualities of the composite materials that form most of the jet.

Television footage of the 787 at Heathrow showed damage to the top of the jet's body near the passenger doors at the rear of the 787. That area of the aircraft typically houses the crew rest compartment, but two people familiar with the jet's layout say that Ethiopian's 787's likely do not have this overhead bunk. The 787's twin lithium-ion batteries are installed below the floor in electrical bays near the nose and between the wings of the aircraft underneath the cabin, far from the damaged area visible in the footage.

The safety experts said that where the flames seemingly exited also isn't near the location of the auxiliary power unit or certain electrical panels that have been involved in previous onboard incidents. If the fire originated in any of those areas or the battery compartments—all located in the lower part of the fuselage—the flames either burned through the floor or crept up inside the skin of the 787. Emergency crews and investigators should be able to pinpoint the origin shortly, these experts said.

One person familiar with the preliminary information the airline conveyed to Boeing and its suppliers said there were no obvious patterns of battery problems or malfunctions on the Ethiopian 787.

Dreamliners also have suffered a spate of smaller technical glitches that have forced airline operators to delay and cancel numerous flights. Those types of issues aren't necessarily uncommon for a new jetliner like the Dreamliner, which first began carrying passengers in 2011. However, a fire aboard an aircraft is a considerably more serious event and is likely to be evaluated separately from the jet's teething issues.

In a separate incident on Friday, another 787 aircraft suffered problems Friday when a Thomson Airways flight was grounded because of "technical issues," a spokesman for the airline said. The flight had taken off from U.K.'s Manchester airport and was headed to Florida's Orlando Sanford International Airport, but had to return to Manchester "as a precautionary measure," the spokesman said.

The aircraft, which can carry some 290 passengers, was near capacity. There were no injuries and passengers disembarked. Engineers were inspecting the plane, the spokesman said.

United has been bedeviled by "several" flight cancellations due to a variety of issues involving the aircraft since the model was allowed to resume operations in late April—although the frequency of the problems has diminished recently, the United spokeswoman said. The latest was on Tuesday when a flight from London to Houston was scratched after pilots saw a message indicating that something was wrong with the plane. After mechanics checked and found the message was false, the crew had "timed out" and wasn't allowed to fly, the company said.

Ethiopian Airlines, one of Africa's oldest and fastest-growing carriers, was the first airline to reintroduce the 787 in late-April after the jet's 3½ month grounding. The airline took delivery of its first 787 in August 2012, and currently operates four of the long-haul aircraft in its fleet.

Robert Stallard, an analyst for RBC Capital Markets, said in a note after the fire that "any issues with the aircraft will likely face heightened scrutiny" given the battery problems. But he noted that during the 787's grounding, production remained on schedule and Boeing's shares held up. "We could see a similar situation this time around," he wrote, recommending investors buy shares on Friday's drop.