LONDON (Reuters) - A Boeing 787 Dreamliner operated by Ethiopian Airlines caught fire at Britain's Heathrow airport on Friday in a fresh blow for the U.S. planemaker which earlier this year was forced to ground the new planes for three months after battery fires.
Boeing shares tumbled by as much as 7 percent, wiping $5.4 billion off its market capitalization after television footage showed the Dreamliner surrounded by foam used by firefighters at Heathrow. At 1745 GMT, shares were down 3.2 percent at $103.50.
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.
Television footage showed an area on the fuselage in front of the tail that appeared to be scorched.
It was not clear if the fire was related to the batteries, which were the cause of the previous fires on the Dreamliner.
"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."
Boeing said it was aware of the fire and that had people on the ground working to understand the causes of it. The U.S. Federal Aviation Administration said it was aware of the fire and was in contact with Boeing.
"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 telephone 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 Boeing Dreamliner operated by Thomson Airways returned to the United Kingdom due to technical issues 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.
Boeing's 787 Dreamliner was grounded by regulators in January after batteries burned on two of the jets within two weeks. It resumed flying in April, with Ethiopian Airlines being the first carrier to put it back into passenger service.
The new high-tech jet came under intense scrutiny and Boeing redesigned the battery system to add more layers of protection against fire. Boeing began installing reinforced lithium-ion battery systems on the 787 in April.
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 U.S. fleet grounding in 34 years.
The plan approved by the Federal Aviation Administration 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 787 uses a powerful electrical system to drive air conditioning and hydraulic functions that are run from compressed air on traditional aircraft designs. That electrical system experienced fire during its development which also prompted changes in its electrical panels.
The Dreamliner 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 web site. The plane was due to make the return journey later on Friday.
Asked whether the incident could lead to the renewed grounding of Dreamliner jets, 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). EASA was not immediately available to comment.
Ethiopian Airlines Dreamliners are powered by General Electric GEnx engines.
Aircraft graphic: http://link.reuters.com/rax39t(Reporting by Rhys Jones, Estelle Shirbon, Mark Anderson, Michael Holden in London; writing by Guy Faulconbridge and Kate Holton; editing by Jane Barrett and David Evans)