Members of the National Transportation Safety Board listen during a hearing… (Jonathan Ernst, Bloomberg )
The National Transportation Safety Board began a two-day investigative hearing in Washington into a fire that broke out on Boeing Co.'s 787 Dreamliner passenger jet because of overheating in its lithium-ion battery systems.
The NTSB still hasn't found a root cause of the fire that occurred Jan. 7 at Boston's Logan International Airport. Ahead of the hearing Tuesday, the board issued hundreds of pages of documents that show five years of history in the development and design approval of the battery system.
Much of the testing was left to Boeing and its battery suppliers. They determined that the likelihood of smoke or fire from a 787 battery would occur fewer than once in every 10 million flight hours. But there already have been two crucial battery events on the 787 fleet with fewer than 52,000 flight hours.
"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," NTSB Chairwoman Deborah Hersman said at the hearing.
The hearing, which took place over eight hours Tuesday, came just days after the Federal Aviation Administration approved a fix for the 787 fleet, which has been grounded since January. The FAA's approval clears the way for the jet's return to flight — possibly as early as this month.
NTSB members asked questions of representatives from the FAA, Boeing, battery maker GS Yuasa Corp. of Japan, and electrical system maker Thales of France.
Boeing has delivered 50 of the new planes to eight airlines worldwide, including United Airlines, the only U.S. carrier that has 787s in its fleet.
All 787s were grounded after the Jan. 7 battery fire broke out on a 787 operated by Japan Airlines at Boston's Logan International Airport and a second battery incident occurred less than two weeks later on an All Nippon Airways flight in Japan.
The 787's lithium-ion battery system contains a cluster of eight individual cells packaged together in one box. The 787 is the first large commercial aircraft to use the technology on such a large scale.
The FAA has been aware of the chance of flammability of lithium-ion batteries for years. When the agency was certifying the Dreamliner for flight operation, it issued special conditions in 2007 for lithium-ion battery installations on the plane because regulations don't cover the novel technology.
Mike Sinnett, Boeing's chief project engineer for the 787 program, said the 787 certification effort was the most extensive effort in the company's history.
"The FAA dedicated over 200,000 hours of certification of the 787 program," Sinnett said during the hearing. Testing on the battery system was "rigorous and subject to scrutiny," he said. He added that in hindsight, he would have challenged the testing process.
The FAA said Friday that for the 787 to return to flight operations, it will require airlines to install containment and venting systems for the batteries. The agency will also instruct carriers to replace the batteries and their chargers with modified components.
To make sure the work gets done, the FAA has teams of inspectors at the modification sites. The FAA said it would not let any modified 787 take to the sky until it approves the work.
Boeing's stock rose $1.24, or 1.4%, to $88.18 on Tuesday. The Chicago company will report first-quarter earnings Wednesday.