Boeing Co.’s assertion that U.S. investigators ruled out a fire within the battery case of a Japan Airlines Co. 787 is premature, a National Transportation Safety Board spokesman said.
Investigators examining the Jan. 7 fire aboard the Dreamliner in Boston haven’t ruled out that flames erupted within the lithium-ion battery container, Peter Knudson said today in response to questions about the issue.
The 787, Boeing’s most sophisticated jet, has been grounded worldwide since Jan. 16 after the JAL incident and a battery overheated on a second Dreamliner in Japan. While the battery aboard the All Nippon Airways Co. smoked and was charred, it didn’t erupt in flames.
Boeing’s proposed changes to the battery were approved for testing by the U.S. Federal Aviation Administration March 12, the first step toward getting the plane back in the air. The FAA approved Boeing’s plan even though the safety board hasn’t found the cause of the JAL incident. Boeing officials said today in Tokyo they expect the plane to be flying again within weeks.
Michael Sinnett, Boeing’s chief project engineer, said in the briefing that investigators hadn’t found evidence of flames within the Boston battery’s container box, an indication it worked as designed to limit damage from a battery failure.
A witness who tried to fight the Jan. 7 fire said he saw 3-inch (7.6-centimeter) flames outside the lithium-ion battery, and the NTSB has found evidence of high temperatures within battery cells that failed, according to preliminary safety-board documents released March 7.
Preliminary estimates are that temperatures within the case exceeded 570 degrees Fahrenheit (299 degrees Celsius), according to a factual report released by the NTSB March 7. Firefighters reported the battery exploded as they attempted to extinguish it, according to the NTSB report.
Sinnett said the reports of fire and explosion weren’t accurate.
Boeing is redesigning its batteries to ensure a fire isn’t possible. Among the new features will be a fire-resistant stainless steel case that will prevent oxygen from reaching the cells so fire can’t erupt, Sinnett said.
Marc Birtel, a Boeing spokesman, didn’t respond immediately to an e-mail request for comment.