A Boeing 787 Dreamliner operated by Ethiopian Airlines caught fire at London's Heathrow airport on Friday in a fresh blow for the US plane maker.
Heathrow briefly closed both its runways to deal with the fire which broke out while the aircraft was parked at a remote stand. There were no passengers aboard the plane.
It was not clear if the fire was related to the batteries, which led to the worldwide grounding of the 787 in January. Pictures from Heathrow showed an area just in front of the tail that appeared to be scorched.
The 787's two batteries are in electrical compartments located low down and near the front and middle of the plane, while the visible damage to the Ethiopian plane appears to be on top of the fuselage, toward the rear, according to video from the scene.
"A Boeing 787 Dreamliner suffered an on board internal fire," a Heathrow spokeswoman said. "The plane is now parked at a remote parking stand several hundred meters away from any passenger terminals."
Former US National Transportation Safety Board Chairman Mark Rosenker said the Heathrow incident was extraordinary news, coming so soon after the fleet had returned to service, but he cautioned against jumping to conclusions.
"It's very early. No one knows where the fire started at this point," Rosenker told Reuters news agency, adding it could be something as simple as a coffee pot left on in a galley.
Boeing said it was aware of the fire and it had people on the ground working to understand the causes of it. The US Federal Aviation Administration said it was in contact with Boeing.
The plane which caught fire in London was the first of the 787 fleet to resume flight after the battery-related grounding.
"This is terrible for the Dreamliner, any event involving fire and that airplane is going to be a PR disaster for Boeing," Christine Negroni, an aviation writer and safety specialist based in New York, said in a phone interview.
"Because of the battery issue, the public is even more sensitive to events that happen to the Dreamliner. Even if they are normal, benign teething problems, that subtlety is going to be lost on the public," she said.
Another 787 operated by Thomson Airways returned to the UK due to technical issues on Friday as a precaution, TUI Travel said.
Ethiopian Airlines said its aircraft had been parked at Heathrow for more than eight hours before smoke was detected.
Richard Aboulafia, a senior aerospace analyst at the Teal Group, said early evidence, including images of the jet, suggest the battery is not the issue because of the location of the fire.
Another person familiar with the aircraft's configuration said the damaged area appears close to galleys and environmental control systems, but added that it was too early to link the fire to any specific equipment.
The Dreamliner was grounded by regulators in January after batteries overheated on two of the jets within two weeks.
Boeing was forced to halt deliveries of the jet while it was grounded and airlines stopped ordering the plane during that period. Orders have since resumed and Boeing has logged 83 787 orders this year, bringing its current order book to 930 planes.
The 787 resumed flying in April, with Ethiopian Airlines being the first carrier to put it back into passenger service.
The high-tech jet came under intense scrutiny and Boeing redesigned the battery system to add more layers of protection against fire.
Teams of engineers were dispatched by Boeing worldwide to install the stronger battery casing and other components designed to prevent a repeat of the meltdowns that led to the first US fleet grounding in 34 years.
The plan approved by the FAA called for Boeing to encase the lithium-ion batteries in a steel box, install new battery chargers, and add a duct to vent gases directly outside the aircraft in the event of overheating.
The NTSB has still not issued a final report on the cause of the 787 battery issues but Boeing said its redesign addressed more than 80 potential causes. The NTSB said it would send a representative to assist in the Heathrow investigation.
The 787 uses a powerful electrical system to drive air conditioning and replace hydraulic functions, taking less power from the engines than traditional aircraft designs. That electrical system experienced fire during its development which also prompted changes in its electrical panels.
The 787 which caught fire at Heathrow on Friday was delivered to Ethiopian Airlines in November last year.
It arrived at Heathrow from Addis Ababa in the early hours of Friday, according to the Flightradar monitoring site. The plane was due to make the return journey later on Friday.
Asked whether the incident could lead to the renewed grounding of 787s, a spokesman for Britain's Civil Aviation Authority said decisions on the airworthiness of particular models of plane were made by the European Aviation Safety Agency (EASA).
An EASA spokesman said it was too early to say whether the aircraft would be grounded again.
Several airlines said they were continuing to operate their 787s, including ANA, Japan Airlines, LOT and United.