LONDON (AP) -- Two Boeing 787 Dreamliner planes ran into trouble in England on Friday, with a fire on one temporarily shutting down Heathrow Airport and an unspecified technical issue forcing another to turn back to Manchester Airport.
The incidents are unwelcome news for Chicago-based Boeing Co., whose Dreamliners were cleared to fly again in April after a four-month grounding due to concerns about overheating batteries.
The fire at Heathrow involved an empty Ethiopian Airlines plane, which was parked at a remote stand of the airport after arriving at the airport. British police said the fire is being treated as unexplained, and that there were no passengers on board at the time of the fire. Heathrow's runways reopened after about an hour.
Boeing spokesman Marc Birtel said in an email that the company had personnel on the ground at Heathrow and that the company "is working to fully understand and address" the situation.
The U.S. National Transportation Safety Board said Friday that it was sending a representative to London to assist British authorities with their investigation of the fire.
Ethiopian Airlines was the first airline to resume using the 787, with a flight on April 27 from Ethiopia's capital of Addis Ababa to Nairobi, Kenya, after the battery incidents.
The registration number of the plane at Heathrow —ET-AOP — is the same as the aircraft used in the April 27 flight. Randy Tinseth, vice-president of marketing for Boeing's commercial unit, was on that initial flight and said that it "left on time, landed early and was truly perfect."
Ethiopian Airlines could not immediately be reached for comment after Friday's incident, and it was not clear how long the plane had been parked at its remote stand.
Soon after the fire at Heathrow, U.K. tour operator Thomson Airways confirmed that one of its Boeing 787 Dreamliner planes travelling from England to the U.S. had to turn back after experiencing a technical issue.
Thomson said that flight 126 travelling from Manchester Airport to Sanford, Florida had returned to Manchester "as a precautionary measure."
It did not specify the nature of the technical issue, but said all 291 passengers had disembarked from the plane and engineers are inspecting the aircraft.
Richard Aboulafia, an analyst with the Teal Group Corporation, said it was too early to comment about the fire at Heathrow except that this is "not a welcome development" for Boeing.
While it was unclear what caused either incident, investors fear that Boeing's lithium-ion batteries could again be the culprit. Shares in the aerospace company were down 4.9 percent to $99.58 in afternoon on news of the Heathrow fire.
Television images showed nearly a dozen fire trucks on the scene at Heathrow and firefighters standing around the Ethiopian Airlines plane.
Fire-retardant foam appeared to have been sprayed. What appeared to be some scorch marks were visible at the rear of the plane, in front of the tail.
The Dreamliner suffered battery incidents in January, including an emergency landing of one plane and a fire on another. U.S. federal authorities lifted the grounding order on April 19, and several airlines have recently resumed flying their Dreamliners.
None of the incidents caused any serious injuries. But the January grounding embarrassed Boeing and disrupted schedules at the eight airlines that were flying the planes. The company had delivered 50 of the planes worldwide.
Boeing never did figure out the root cause of the battery incidents. Instead, it redesigned the battery and its charger. The changes included more heat insulation between each cell and charging the battery to a lower maximum voltage.
Associated Press writers Raphael Satter and James Brooks in London and Scott Mayerowitz in New York contributed to this report.