NTSB Finds Short-Circuiting in Boeing Dreamliner Battery, Probe Could Be Lengthy

By Paul Riegler on 24 January 2013
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Cockpit of an ANA Dreamliner

Cockpit of an ANA Dreamliner

The National Transportation and Safety Board said on Thursday that its probe into problems with the lithium-ion batteries installed on two Boeing 787 Dreamliner aircraft may be far from over.

The battery in the Japan Airlines 787 that caught fire while parked at Boston’s Logan Airport earlier this month showed signs of short-circuiting and a phenomenon known as “thermal runaway,” in which a chemical reaction causes an increase in temperature that causes causes the chemical reaction to increase and results in progressively hotter temperatures, said federal investigators.

According to NTSB chairman Deborah Hersman, it’s still not clear which came first: the short-circuiting or the thermal runaway.  A cause for either issue has yet to be determined, she said during a briefing on the NTSB’s investigation.  Hersman terms both the short-circuiting and thermal runaway as “symptoms,” and refused to say whether either was the cause of the problem that caused two fires in two separate 787s.

“These are all symptoms that something’s wrong,” she said. “Understanding what came first and what triggered the next thing, that’s information we are working to identify.”

Foreshadowing a lengthy investigation, Hersman said that, despite the fact that there were no deaths, injuries, or hull losses, “These events should not happen.”

“There are multiple systems to prevent against a battery event like this,” she said. “Those systems did not work as intended. We need to understand why.”

“It is really very hard to tell at this point how long the investigation will take,” she added. “What I can tell you is we have all hands on deck. We are working hard to determine what the failure mode here is and what actions have to be taken.”

Boeing issued a brief statement acknowledging today’s NTSB announcements, adding that the company was “working this issue tirelessly” in conjunction with customers and regulatory and investigative bodies.

Boeing also stated it regretted the impact that the grounding of the Dreamliners has had “on the operating schedules of our customers and their passengers.”

The Dreamliner was grounded by aviation authorities and airlines around the world on Wednesday after a second battery-related problem caused a fire onboard a Dreamliner aircraft while on a domestic flight in Japan.

The high-tech Boeing 787 Dreamliner has more electrical systems than earlier aircraft. These systems perform a variety of tasks including de-icing the wings, pressurizing the cabin, and operating hydraulic pumps. In addition, the 787 uses electric brakes while other aircraft have hydraulic ones. The Dreamliner has six generators that produce a total of 1.45 megawatts, enough to power 400 homes.

The aircraft has two main lithium-ion batteries, each roughly twice the size of a standard car battery. One, located in the front of the aircraft, supplies power for the plane’s startup functions and ground operations and also serves as backup power for the electric brakes. The second is in the back of the plane and is used to start the aircraft’s auxiliary power unit (APU), which is a small engine that powers the plane while it is on the ground. Malfunctions have been reported with both batteries.

The first Dreamliner took flight in late 2011 and was operated by launch customer ANA.  Boeing has delivered over 50 Dreamliners since the launch.

UPDATE 1 – This article was updated on January 24, 2012 after Boeing released a statement on the NTSB update.

(Photo: Accura Media Group)


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