NTSB: 787 battery approval should be reconsidered

WASHINGTON (AP) — The government should reassess its safety approval of the Boeing 787 lithium ion batteries, the nation's top accident investigator said today.

Deborah Hersman, the National Transportation Safety Board chairwoman, said the board's investigation of last month's battery fire in a Japan Airlines 787 "Dreamliner" while it was parked in Boston shows the fire started with multiple short-circuits in one of the battery's eight cells. That created an uncontrolled chemical reaction known as "thermal runaway" and spread to the rest of the cells, she said.

That's at odds with what Boeing told the Federal Aviation Administration when the agency was working to certify the innovative aircraft for flight, Hersman said. The manufacturer asserted its testing showed that any short circuiting could be contained within a single cell, preventing thermal runaway and fire, she said.

Boeing's testing also showed the batteries were likely to cause smoke in only 1 in 10 million flight hours, she said. But the Boston fire was followed nine days later by a smoking battery in an All Nippon Airways plane that made an emergency landing in Japan.

The 787, Boeing's newest and most technologically advanced plane, has recorded less than 100,000 flight hours, Hersman noted.