NTSB chairman updates 787 battery investigation, questions certification

A top federal official Thursday identified what started a battery fire aboard a Boeing 787 last month before questioning how the high-performance but overheating-prone battery type was certified for use on the new jetliner.

National Transportation Safety Board Chairman Deborah Hersman said her agency’s investigation suggests a short circuit in one cell of the plane’s auxiliary power unit battery that rippled throughout the battery and sparked the blaze.

How that happened is still unclear. But Hersman said the Jan. 7 incident in Boston and an in-flight battery malfunction in Japan the following week have already rebutted two fundamental safety conclusions Boeing drew — and that the Federal Aviation Administration accepted — regarding its prize plane’s lithium ion batteries.

“The assumptions used to certify the battery must be reconsidered,” Hersman said.

Boeing’s tests indicated a short circuit in one cell of the battery would not spread to the battery’s seven other connected cells, she said.

“However, our investigative findings with respect to the event battery show that when a short circuit did occur it resulted in cell-to-cell propagation, in a cascading manner, and a fire,” Hersman said.

Boeing also estimated there would be a smoky battery incident only once every 10 million hours of flight.

“That assessment was not demonstrated in reality,” Hersman said, noting on consecutive weeks, less than 100,000 flight-hours into 787 service, there were two incidents on two different airplanes — and one involved a fire, not just smoke.

The Wall Street Journal has reported that Hersman is a leading contender to replace outgoing Transportation Secretary Ray LaHood. The FAA, which certified the Dreamliner’s batteries after imposing special conditions, is an agency of the Department of Transportation.

In a statement, Boeing said it “welcomes” the NTSB’s progress. It also said it committed to working with government investigators and regulators to make its planes safe.

“We are working collaboratively to address questions about our testing and compliance with certification standards, and we will not hesitate to make changes that lead to improved testing processes and products,” the statement read.

Carter Leake, who covers the aerospace and defense industries for BB&T Capital Markets and has downgraded Boeing’s stock twice this year, was not encouraged by Hersman’s remarks.

Leake predicted the 787 troubles would be a long-term problem for the company in a research note last week. He said Thursday’s briefing, especially Hersman’s words about certification, confirmed his thinking.

“Once we’re done with finding root cause, which we still don’t have, we’re moving onto a bigger issue, which is should this battery have been certified at all?” Leake said. “Recertification has a time element that only works against Boeing.”

Among other evidence of the short circuit, Hersman said the flight data recorder in the Japan Airlines 787 that caught fire while parked in Boston showed the battery’s voltage drop to 28 from 32.

“The body of evidence strongly suggests that the event initiated in cell number six,” she said.

It then spread to other cells in the lithium-ion battery through a process called “thermal runaway.”

Hersman said the NTSB has ruled out two possible causes of the short-circuiting: mechanical damage and an external short.

Investigators are looking at the design of the battery, the manufacturing process and the way the battery is charged, Hersman said. They are looking for evidence of contamination or folds or pinches in the cells.

Hersman also said the investigation is looking at the connections between the cells in the battery and the spacing between the cells, the kinds of design changes that The Wall Street Journal has reported Boeing also is working on to minimize fire risks.

She said her agency’s investigators have been working “around the clock” to solve the mystery. “We have a lot of work to do,” she said.

But given the damage to the battery, Hersman could not guarantee the root cause would be determined.

She said the NTSB will issue an interim factual report in 30 days but added that report would not be definitive.

Hersman declined to speculate what might have happened if the fire occurred while in the air, because that is beyond the purview of the NTSB investigation and her agency wants to “stay in our lane” by solely investigating the event.

The Japan Transportation Safety Board is investigating the Jan. 16. in-flight battery malfunction that prompted the global grounding of the revolutionary plane model.

Hersman said the NTSB and JTSB are working together but that the investigations are at different phases. “I don’t think we’re in a position to do a comparative analysis at this point in time,” she said.

Meanwhile, production of 787s continues. Between final assembly plants in Everett and North Charleston, Boeing is making five planes a month now and hopes to double that rate by the end of the year.

Hersman said it is still up to the Federal Aviation Administration to determine what Boeing needs to do to get the grounded fleet of 787s flying again.

“But if we learn lessons that we think are applicable to other scenarios, we will be sure to pass those on,” she said.

“It is important to get smart about these batteries,” Hersman said. “Everybody wants to understand what happened here and make safety improvements.”

Reach Brendan Kearney at 937-5906 and follow him on Twitter at @kearney_brendan.