The Federal Aviation Administration said Wednesday that it was grounding all Boeing 787s operated by U.S. carriers until it can determine what caused a new type of battery to catch fire on two planes in nine days.
The decision follows incidents involving a plane parked in Boston and one in Japan that was forced to make an emergency landing Wednesday morning after an alarm warning of smoke in the cockpit. The problems prompted All Nippon Airways and Japan Airlines to voluntarily ground their 787s.
The FAA's emergency directive, issued Wednesday night, initially applies to United Airlines, the only U.S. carrier using the new plane, with six 787s. But the agency said it expected international regulators would take similar action. That would ground all 50 of the 787s delivered so far.
Boeing, based in Chicago, has a lot riding on the 787, and its stock dropped nearly 3.4 percent Wednesday, to $74.34. The company has outlined ambitious plans to double its production rate to 10 planes a month by the end of 2013. It is also starting to build a stretched-out version and mulling an even larger one after that.
The grounding an unusual action for a new plane focuses on one of the more risky design choices made by Boeing, namely to make extensive use of lithium ion batteries aboard its airplanes for the first time. Until now, much of the attention on the 787 was focused on its lighter composite materials and more efficient engines, meant to usher in a new era of more fuel-efficient travel, particularly over long distances. The batteries are part of an electrical system that replaces many mechanical and hydraulic ones common in previous jets.
The 787's problems could jeopardize one of its major features, its ability to fly long distances at a cheaper cost. The plane is certified to fly 180 minutes from the nearest airport. The government is unlikely to extend that to 330 minutes, as Boeing has promised, until all problems had been resolved.
For Boeing, "it's crucial to get it right," said Richard Aboulafia, an aviation analyst at the Teal Group in Fairfax, Va. "They've got a brief and closing window in which they can convince the public and their flying customers that this is not a problem child."
The 787 uses two identical lithium-ion batteries, each about 1 1/2 to twice the size of a car battery. One battery, in the rear electrical equipment bay near the wings, is used to start the auxiliary power unit, a small engine in the tail that is used most often to provide energy for the plane while it is on the ground. The other battery, called the main battery, starts the pilot's computer displays and serves as a backup for flight systems.
The maker of the 787's batteries, Japan's GS Yuasa, has declined to comment.
Boeing has defended the novel use of the batteries and said it had put in place a series of systems meant to prevent overcharging and overheating.
In a conference call last week with reporters, Boeing's chief engineer for the 787, Mike Sinnett, said that the company had long been aware of possible problems with lithium-ion batteries, but it had built numerous redundant features to keep any problems with the batteries from threatening the plane in flight. He said that the batteries had not had any problems in 1.3 million hours of flight, and that Boeing was trying to understand what had caused the problems.
Sinnett said that if the lithium-ion batteries started a fire, it would be nearly impossible to put out because the batteries produce oxygen when combusting. Sinnett said that the plane was designed to survive such an event in flight, when the cabin's air-pressure system protects passengers and allows the plane to vent the smoke outside. The plane is also designed, he said, to contain a fire to a small area.
"Fire suppressants just won't work on a situation like that," he said in the conference call. "So something like that is very difficult to put out." Heat from the fire on the plane parked in Boston last week was so extreme that it melted the bolts holding the battery to the equipment rack. Firefighters had to use a hydraulic tool to cut it loose.
The solutions to the battery problem could be simple, analysts said, such as encasing the battery in a stronger shell or monitoring the batteries more closely. But if Boeing had to switch to more conventional nickel-cadmium or lead-acid batteries, they would have to be larger, adding more weight to the plane, cutting into the plane's fuel-savings potential.
Wednesday's emergency landing was the latest in a string of incidents for the 787, which also included an electrical failure, fuel leaks and other smaller mishaps. But the latest event raised concerns that the 787's problems were potentially more serious than previously thought and led to doubts about the plane's safety and reliability.
As part of Wednesday's emergency directive, the government said it would "validate that the 787 batteries and the battery system on the aircraft are in compliance with the special condition the agency issued as part of the aircraft's certification."
Eight airlines now fly the 787, which entered service in November 2011. All Nippon Airways and Japan Airlines own 24 of them. The other operators are Air India, Ethiopian Airlines, LAN Airlines of Chile, LOT of Poland and Qatar Airways.
Orders for about 800 additional 787s are in the pipeline.
The airplane's six power generators generate enough electricity to power 500 houses. By contrast, the Boeing 777, a larger aircraft, can generate only a fifth of that power.
Replacing batteries on the 787 with different ones is theoretically possible but would be costly, said Hans Weber, the president of Tecop International, an aviation consulting firm. He estimated that different batteries could double the weight of the current systems and would be twice the size.