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NTSB update on JAL Boeing 787 battery fire investigation

The National Transportation Safety Board (NTSB) released a fourth update on its investigation into the Jan. 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston. (Earlier post.)

The event airplane, JA829J was delivered to JAL on December 20, 2012. At the time of the battery fire, the aircraft had logged 169 flight hours with 22 cycles. The auxiliary power unit battery was manufactured by GS Yuasa in September 2012.

NTSB investigators have continued disassembling the internal components of the APU battery in its Materials Laboratory in Washington, and disassembly of the last of eight cells has begun. Examinations of the cell elements with a scanning-electron microscope and energy-dispersive spectroscopy are ongoing.

A cursory comparative exam has been conducted on the undamaged main battery. No obvious anomalies were found. More detailed examination will be conducted as the main battery undergoes a thorough tear down and test sequence series of non-destructive examinations.

In addition to the activities at the NTSB lab, members of the investigative team continue working in Seattle and Japan and have completed work in Arizona.

  • In Arizona, the airworthiness group completed testing of the APU start power unit at Securaplane in Tucson and the APU controller at UTC Aerospace Systems in Phoenix. Both units operated normally with no significant findings.

  • Two additional NTSB investigators were sent to Seattle to take part in FAA’s comprehensive review. One of the investigators will focus on testing efforts associated with Boeing’s root cause corrective action efforts, which FAA is helping to lead. The other will take part in the FAA’s ongoing review of the battery and battery system special conditions compliance documentation.

  • The NTSB-led team completed component examination of the JAL APU battery monitoring unit at Kanto Aircraft Instrument Company, Ltd., in Fujisawa, Kanagawa, Japan. The team cleaned and examined both battery monitoring unit circuit boards, which were housed in the APU battery case. The circuit boards were damaged, which limited the information that could be obtained from tests, however the team found no significant discoveries.



Thales and Boeing may have to look for safer battery & control technologies? Many other batteries & control systems could probably do the job safely. Proper selection-installation-operation is essential.

What is Airbus and Bombardier using?


So what do you do when the safety monitor unit(BMS) is the failure point? Two things LION batteries, no matter what chemistry, don't tolerate well; over-charging and over-discharging...if the BMS fails to detect these two conditions, it could allow either charge condition to happen. Or, God forbid, if the BMS also was designed to assist the charger to control current flow into and out of the battery, a failure in these circuits could be the cause of the damaged battery

I believe the BMS function should be simply to monitor the voltages of each battery cell and to disconnect the battery when the voltages are out of the normal range and turn on a warning light. For sure there are backup systems for the battery system on airplanes so you remove the faulty battery from service and use the backup.


I believe the new Airbus A350 uses almost identical Li-Ion batteries but from a different supplier than GS Yuasa.

They argue that their system is safe because of multiple minor but important differences are likely to not have the problem - whatever it is.

There is no truth to the rumor that the A350 is safer because every critical system is 10 pounds heavier than in the dreamliner.

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