Ten months later, the agency allowed Boeing to use the same volatile type of battery on its new 787 plane. But in Boeing’s case, the batteries weighed 63 pounds each, were to be used in critical flight systems as well as to provide backup power, and would be charged and discharged much more often. Yet the agency’s ruling used identical language — it could have been just cut and pasted — in laying out the broad safeguards for using the batteries that it had given Airbus to follow.

The use of lithium batteries in the 787 is at the center of the difficulties involving Boeing. The plane maker has staked its reputation on the success of the 787, an aircraft it nicknamed the Dreamliner. All 50 787s delivered to airlines worldwide were grounded last week until investigators in the United States and Japan find out why two lithium batteries failed in recent weeks, causing a fire on one 787 and damage to another that led to an emergency landing.

It also raises fundamental questions about how federal regulators certify new technology and how they balance advances in airplane design and engineering with ensuring safety in commercial flying. In addition to finding out what went wrong, these issues will be examined in a federal investigation and at future Senate hearings.

When it approved Boeing’s request in 2007, the F.A.A. said it had limited experience with the use of lithium-ion batteries in commercial airplanes, though it acknowledged that the batteries themselves were more prone to fire than traditional nickel-cadmium or lead-acid batteries.

Still, the agency approved the technology on the assumption that Boeing could make the batteries work and that computer controls could prevent batteries from overcharging or overheating. The agency also specified that any fire or toxic leak be contained and not damage any surrounding electrical systems.

At the same time, the agency brushed off concerns raised in 2006 and 2007 by the Air Line Pilots Association that a fire in flight would be difficult to extinguish and that flight crews should be given extra training.

“We have concluded that providing a means for controlling or extinguishing a fire — such as stopping the flow of fluids, shutting down equipment, or fireproof equipment” was an “adequate alternative to requiring the flight or cabin crew to use extinguishing agents,” the agency said in its 2006 decision about the Airbus A380.

Experts said that regardless of the cause of the 787’s problems, the charred remains of the battery that caught fire earlier this month in a plane in Boston raised the question of whether the safeguards functioned properly.

On Wednesday, the National Transportation Safety Board, which is investigating the battery fire in Boston, said that all eight cells in the battery had sustained “varying degrees of thermal damage.” Six of them have been scanned and disassembled for further examination.

Many battery experts said they viewed Boeing’s decision to use lithium-ion batteries as a reasonable one and pointed out that lithium-ion batteries had also been used in expensive space satellites since around 2000 without serious problems. They said that track record would have added to the confidence Boeing and federal regulators had about using them in commercial airliners.

Jay F. Whitacre, an associate professor of engineering at Carnegie Mellon University, said GS Yuasa, the Japanese company that built the 787 batteries, told the National Aeronautics and Space Administration in a 2008 presentation that it had already supplied batteries for six satellites and had contracts for 50 more. GS Yuasa also said that its satellite batteries had never had a shorting incident in more than 10 years of production.

“That’s pretty compelling,” Professor Whitacre said. “If I had all that data and saw that they were making batteries for 50 more satellites, I’d say that was a reasonable risk to take. My sense is that Boeing did a fairly decent job of picking the right company.”

But another battery expert, Donald Sadoway, a materials chemistry professor at M.I.T., disagreed. He said that sticking with an older type of battery instead of the lighter lithium battery would not have made a huge difference to the 787, adding about 40 pounds, or the equivalent of an extra suitcase per battery.

Matthew L. Wald contributed reporting from Washington.

Article source: http://www.nytimes.com/2013/01/24/business/global/boeing-787-battery-was-not-overcharged-japanese-investigators-say.html?partner=rss&emc=rss