NTSB: 787 Battery Shows Evidence of 'Thermal Runaway'

 - January 24, 2013, 6:55 PM
Joseph Kolly, director of the NTSB office of research engineering, points to damaged electrode windings from the lithium-ion battery removed from the JAL 787. (Photo: Bill Carey)

The damaged lithium-ion APU battery from the Japan Air Lines Boeing 787 that caught fire on January 7 while parked at Boston’s Logan Airport experienced an uncontrolled chemical reaction known as a “thermal runway” and short circuiting, but the cause and sequence of these events are still unknown, according to the U.S. National Transportation Safety Board (NTSB).

Seventeen days into its investigation of the incident, the first of two separate battery failures that led to the grounding of the worldwide 787 fleet, the NTSB conducted an update briefing on Thursday at its Washington, D.C., headquarters. “Today I can tell you what we know so far,” said Deborah Hersman, the board chairman. “We know that the lithium-ion battery experienced a thermal runaway. We know that there were short circuits, and we know that there was a fire. The work that we continue to do will tell us why these things happened.”

Hersman said “cells 5, 6 and 7” of the eight-cell battery unit manufactured by GS Yuasa of Japan “are of particular interest to our investigators because they appear to have experienced the most thermal damage,” based on a computed tomography (CT) scan of the battery assembly and examination of the individual cells.

The NTSB investigative team that responded to the scene reported that damage to surrounding structures and components was confined to a 20-inch radius around the APU battery rack. “The APU battery was spewing molten electrolytes, very hot material,” she said. “We did also see some damage involved with the extrication of the battery as well. The firefighting response teams (took) the battery out before NTSB investigators arrived, so we were examining the scene after the battery was removed.”

Hersman declined to estimate how long the NTSB’s investigation will take. She deferred to the FAA a question about whether the worldwide grounding of the 787 fleet was an overreaction, but said that her board “respects the FAA’s decision.” The JAL battery fire, followed on January 16 by a main battery fire that forced the emergency landing of an All Nippon Airways 787 in Japan, are serious and extraordinary events, she said. “The expectation in aviation is to never experience a fire on board an aircraft. In two weeks time, we saw two cases of battery failures on the 787 and the grounding of the entire fleet by the FAA. The significance of these events cannot be understated.”


1.GCAA in its interim report implicates, batteries of Lithium and Lithium derivatives in the cargo loft of UPS freighter that crashed in 2010 in Dubai.
2.The safeguards to prevent short cicuit did not work, comment by NTSB
3.'The Assumptions used to certify the battery must be reconsidered",Deborrah Hersman of NTSB
4.Boeing says it (Lithium ion) stores more energy than safer chemistries! Sadly this statement betrays Boeings attitude. Flight safety appears to take a backseat.
I worked for over 40 yrs. in both Civil and Military Jets.
Allow me to say that going back to the trusted 'Ni-cad' is the best alternative. For Boeing, no doubt it is a hard decision.

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