The top U.S. transportation safety agency is looking beyond what caused a Boeing Co Dreamliner battery to fail in January at larger lessons that can be applied to the airplane certification process and new technologies.
A two-day hearing at the National Transportation Safety Board headquarters in Washington that began on Tuesday delved into what Boeing and the Federal Aviation Administration knew about volatile lithium-ion batteries when they proposed them for use on the Dreamliner, and how they addressed the risks.
Boeing said that it did not believe during design and testing that a fire could occur in the lithium-ion battery system that failed on the Dreamliner.
Under questioning, Mike Sinnett, Boeing's chief 787 engineer, said: "Any form of internal short circuit could lead to venting of that cell and release of electrolyte, but nothing more than that."
He added: "The only time we were ever able to make a cell vent with fire was with significant overcharging."
The hearing is part of the agency's investigation into what caused a battery to catch fire and burn on a parked 787 Dreamliner in Boston in January. The battery fire occurred after passengers had left the plane, and workers noticed smoke in the cabin. It took firefighters more than an hour to put the fire out.
"We are looking for lessons learned, not just for the design and certification of the failed battery but for knowledge that can be applied to emerging technologies," NTSB Chairman Deborah Hersman said in opening the hearing. "It's imperative to understand how to best oversee their development and certification."
Also in response to questions, Ali Bahrami, the transport airplane manager for the FAA, said the special conditions the agency established for the 787 battery addressed safety concerns for the aircraft "quite eloquently."
He added: "We did the best we could under the circumstances and the knowledge that existed" at the time to develop standards for the battery.
The proceeding is being simultaneously translated into French and Japanese to accommodate journalists and observers from Europe and Japan. In addition to Boeing and the Federal Aviation Administration, the NTSB has called witnesses from GS Yuasa Corp of Japan, which makes the 787 battery, and Thales SA of France, which makes the battery system.