Boeing acknowledged that tests of the lithium-ion batteries on its 787 planes underestimated the risks of fire. Mike Sinnett, Boeing’s chief engineer on the 787, revealed that the calculation that a battery would fail only once every 10 million flight hours only applied to the design of the battery and did not take into account possible flaws in manufacturing. However, the company defended its previous assessment that the hazard was extremely unlikely.
The 787 is the first major commercial airplane to use lithium-ion batteries extensively. On January 7, a Japan Airlines 787 parked at a gate at Boston’s Logan Airport caught fire. In a second incident, an All Nippon Airways plane reported a fire involving a similar battery. These incidents led to the grounding of all 50 of the planes delivered by Boeing so far.
The National Transportation Safety Board held a two-day hearing on the matter. The hearing’s purpose was to determine how Boeing and the Federal Aviation Administration missed the potential for catastrophic failure when the battery was initially certified in 2007 despite years of careful work. Deborah A. P. Hersman, the board’s chairwoman, said, “We are here to understand why the 787 experienced unexpected battery failures following a design program led by one of the world’s leading manufacturers and a certification process that is well-respected throughout the international aviation community.”
Boeing seems to be pointing most of the blame for the battery failures at GS Yuasa, the Japanese manufacturer of the battery. Mr. Sinnett said the battery failure calculation was based on data provided by GS Yuasa. He said, “That value essentially is reached by experience with similar type cells. GS Yuasa had experience with over 14,000 cells of similar makeup. They had millions upon millions of those cells without any cell venting.” Looking forward to the future, the plane’s manufacturers and regulators will have to find ways to cope with rapid changes in technology that may outstrip their ability to predict problems.
