text: Shares of Boeing are sinking after a fire aboard an empty 787 airplane flown by Ethiopian Airlines at Heathrow Airport. 
   
   British police said the fire is being treated as unexplained. 
   
   The entire fleet of 787s was grounded in January for problems involving the plane's lithium-ion batteries. One caught fire at Boston's Logan airport. 
   
   The planes resumed flying in May after Boeing made redesigns to the battery system that were approved by global aviation regulators. Ethiopian was the first airline to resume using the 787. 
   
   Boeing shares fell $7.20, or 6.7 percent, to $99.68, around midday in New York. 
   
   Boeing spokesman Marc Birtel said in an email to The Associated Press that the company has personnel at looking into the event at Heathrow. ||||| Image caption An area in front of the tail area on the fuselage appeared to be scorched 
   
   Flights have resumed at London's Heathrow Airport after a fire on a parked Ethiopian Airlines Boeing 787 Dreamliner jet. 
   
   All runways were closed for nearly 90 minutes after the fire at 16:30 BST. No passengers were aboard the plane at the time, a Heathrow spokesman said. 
   
   Fifty Dreamliners worldwide were grounded in January after malfunctions with the plane's lithium-ion batteries. 
   
   Boeing modified the jets with new batteries and flights resumed in April. 
   
   The Air Accidents Investigation Branch of the Department for Transport has despatched a team to the scene. 
   
   The Ethiopian Airlines Dreamliner in the Heathrow incident - named the Queen of Sheba - flew from Addis Ababa to Nairobi on the first commercial flight since the grounding. 
   
   Pictures of the Heathrow fire showed the Queen of Sheba close to a building and surrounded by fire vehicles. London Fire Brigade said its crews assisted Heathrow staff. 
   
   Fire-retardant foam was sprayed at the airliner, and an area on top of the fuselage in front of the tail appeared to be scorched. 
   
   Ethiopian Airlines said smoke was detected from the aircraft after it had been parked at Heathrow for more than eight hours. 
   
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   Media playback is unsupported on your device Media caption Aerial pictures show the plane surrounded by emergency crews 
   
   A Heathrow spokesman said: "Heathrow's runways are now fully open following an earlier fire on board an Ethiopian Airlines aircraft which the airport's emergency services attended. 
   
   "The aircraft was parked on a remote parking stand and there were no passengers on board. Arrivals and departures were temporarily suspended while airport fire crews attended to this incident. 
   
   "This is a standard procedure if fire crews are occupied with an incident." 
   
   Heathrow reopened shortly before 18:00 BST but was advising passengers to check the status of their flights with the airlines. 
   
   Gatwick Airport said it experienced minor delays on departing flights as it assisted Heathrow with flights that were diverted. 
   
   Meanwhile, Thomson Airways said one of its Dreamliners travelling to Florida returned to Manchester Airport as a precautionary measure, not connected to the Heathrow fire. 
   
   Thomson, which became the first British carrier to operate the aircraft earlier this week, and is taking delivery of eight of the planes, said the plane had "experienced a technical issue". 
   
   British Airways is taking delivery of the first two of its 24 Dreamliners. 
   
   Virgin Atlantic said it "remains committed" to taking on the first of its 16 Dreamliners in September 2014. 
   
   The British pilots' union Balpa said: "The Boeing 787 Dreamliner forms an important part of many of our airlines' future plans, and it is vital that the cause of this fire is established as quickly as possible. 
   
   "All parties in the industry need a full and transparent explanation as to what has been identified as the root causes in this series of events." 
   
   The battery problems followed production difficulties for the Dreamliner, marketed as a quiet, fuel-efficient aircraft carrying between 201 and 290 passengers on medium-range routes. 
   
   It was due to enter passenger service in 2008 but it was not until October 2011 that the first commercial flight was operated by Japan's All Nippon Airways. 
   
   The groundings of all Dreamliners in service in January followed two major incidents concerning the plane's two lithium-ion batteries. 
   
   On 7 January, a battery overheated and started a fire on a Japan Airlines 787 at Boston's Logan International Airport. Nine days later, an All Nippon Airways 787 had to make an emergency landing in Japan after a battery started to give off smoke. 
   
   The two batteries are not used when the 787 is in flight. 
   
   They are operational when the plane is on the ground and its engines are not turned on, and are used to power the aircraft's brakes and lights. 
   
   The new versions of the batteries, which run at a much cooler temperature, are now enclosed in stainless steel boxes. 
   
   Boeing shares fell on the New York Stock Exchange on news of the fire. 
   
   A Boeing spokesman said: "We're aware of the event. We have Boeing personnel on the ground at Heathrow and are working to fully understand and address this." ||||| Thomson Airways says one of its Boeing 787 Dreamliner planes travelling from England to the U.S. had to turn back after experiencing a technical issue. 
   
   The incident is the second to involve one of Boeing Co.'s troubled planes on Friday. Earlier, Heathrow Airport temporarily shut down its runways due to a fire on an empty 787. 
   
   Thomson said that flight 126 travelling from Manchester Airport to Sanford, Florida had returned to Manchester "as a precautionary measure." 
   
   It said all passengers had disembarked from the plane and engineers are inspecting the aircraft. 
   
   THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below. 
   
   A fire on an empty Boeing 787 Dreamliner plane forced Heathrow Airport to temporarily close both its runways Friday. 
   
   The incident comes as unwelcome news for Chicago-based Boeing Co., whose Dreamliners were cleared to fly again in April after a four-month grounding amid concerns about overheating lithium-ion batteries. 
   
   Heathrow said there were no passengers aboard the Ethiopian Airlines plane, which was parked at a remote stand of the airport, and runways reopened after about an hour. British police said the fire is being treated as unexplained. 
   
   Boeing spokesman Marc Birtel said in an email that the company had personnel on the ground at Heathrow and "is working to fully understand and address" the situation. 
   
   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 airline could not immediately be reached for comment. 
   
   Television images showed nearly a dozen fire trucks on the scene at Heathrow and firefighters standing around the Ethiopian Airlines plane, which was parked on a remote stand. 
   
   Fire-retardant foam appeared to have been sprayed, and it was not immediately clear if there was damage to the plane. 
   
   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. 
   
   Shares in Boeing fell 6.5 percent to $99.58 on news of the Heathrow fire. 
   
   ___ 
   
   Associated Press writers Raphael Satter in London and Scott Mayerowitz in New York contributed to this report.
target: – Looks like the Boeing 787's fire issues aren't entirely behind it. A parked Dreamliner, owned by Ethiopian Airlines, caught fire today at Heathrow airport, prompting a suspension of all arrivals and departures to the London airport, the BBC reports. No passengers were aboard, no injuries have been reported, and the airport has since reopened. But the incident is likely to raise more doubts about the benighted Dreamliner—and sure enough, Boeing's stock plunged on the news, the AP reports. And as if that wasn't enough bad news for the plane maker, later another 787 flying from Manchester to the US had to turn around after encountering an unspecified mechanical failure. All 126 passengers aboard have now disembarked safely. The plane's operator, Thompson Airways, describes the emergency landing as a "precautionary measure."