WASHINGTON/NEW YORK The top U.S. transportation safety agency said on Tuesday it is looking beyond what caused a Boeing Co Dreamliner battery fire in January to find larger lessons that can be applied to the airplane certification process and to new technologies.
A two-day public hearing by the National Transportation Safety Board that began on Tuesday delved into what Boeing and the Federal Aviation Administration knew about volatile lithium-ion batteries when they proposed their use on the Dreamliner and how they addressed the risks.
Questioners also examined how the batteries were tested and how the FAA and Boeing responded when better tests became available after the system was approved.
The hearing is part of the NTSB's probe into what caused a battery to catch fire and burn on a parked 787 Dreamliner in Boston in January. The battery fire, one of two failures that month, took more than an hour to put out. Video at the hearing showed smoke billowing from the cabin when fire fighters opened the plane's rear door. The first fire crew arrived within a minute of the report of the blaze, officials said.
"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.
With witnesses discussing voltage, impedance and other battery properties, the hearing was often highly technical. Simultaneous translation for officials from France and Japan occasionally made it difficult for questioners to pinpoint answers, discern meaning and ask follow-ups.
During the hearing, Hersman sometimes played the role of referee, asking questioners if they got their answers and warning Boeing executives against "obfuscation." Participants even struggled to agree on a definition of "thermal runaway" to describe how a battery overheats.
But the hearing revealed that the FAA and Boeing stand by their design and certification decisions.
Asked what, in hindsight, Boeing would do differently, Mike Sinnett, Boeing's chief 787 engineer, said the system worked by preventing a catastrophe and "from that perspective, that validates our process."
He added the incident taught Boeing it should challenge test assumptions, use tougher test criteria and "seek to understand the test criteria a little bit more."
The FAA, answering the same question, said it needs to ensure it can "dig deeper to find out what (an incident) is telling us, so that we can absorb that information and roll it into future designs," said Ali Bahrami, the transport airplane manager for the FAA.
Under the current FAA approval process, however, the agency stays at a high level, approving how Boeing will comply with requirements, but leaving it up to Boeing and its suppliers to conduct tests and analysis. The FAA does not conduct its own tests, but serves as "an independent set of eyes," Bahrami said.
The NTSB plans to delve more deeply on Wednesday into the close ties between the FAA and the companies it regulates, Hersman said.
Much of the discussion on Tuesday focused on tests that Boeing and its partners performed on the battery. Officials from GS Yuasa Corp of Japan, which makes the 787 battery, and Thales SA of France, which makes the battery system, were on hand to help answer those queries.
The tests had predicted the chance of a fire failure was one in 10 million flight hours, but those results were proved wrong when two batteries overheated and emitted smoke within two weeks on two airplanes. The second incident, during a flight in Japan, is being investigated by the Japanese. The entire fleet of planes had less than 60,000 hours of flight time.
Boeing said that, during design and testing, it did not believe fire could occur in the lithium-ion battery system on the Dreamliner.
"Any form of internal short circuit could lead to venting of that cell and release of electrolyte, but nothing more than that," Sinnett said.
Speaking after the hearing, Hersman said that some of the testing done on the battery "really didn't replicate the worst-case conditions that we saw in the events of January."
Bahrami, the FAA manager, said that special conditions the agency established for the 787 battery addressed safety concerns for the aircraft "quite eloquently."
"We did the best we could under the circumstances and the knowledge that existed" at the time, he said.
The NTSB also released a timeline of the FAA's approval for the Dreamliner battery and a less extensive lithium-ion system for the Airbus A380 superjumbo jet.
The timeline showed the FAA approved Boeing's system before Airbus, even though both applied in the same year, and that Boeing's use was much more extensive.
It also showed that the FAA asked an outside industry group known as RTCA to develop standards for lithium ion batteries just after a fire broke out at SecuraPlane, the company making the charger for Boeing's Dreamliner system.
The industry group finished the standard, known as DO-311, five months after the FAA approved Boeing's battery system. But Boeing and the FAA never applied it to the Dreamliner.
"Why didn't you rebaseline" using the new standard? Hersman asked.
Steve Boyd, an FAA manager, said the RTCA tests were "in some cases more severe than they needed to be."
Boeing has redesigned the system in recent months and tested it to DO-311 standards as part of the FAA certification.
Last week, the FAA approved the new system, clearing the way for Boeing to install it in the 50 aircraft it has delivered to airlines around the world.
Commercial flights are expected to start as early as this month.