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NTSB, JAL 787 Airplane APU Battery Did Not Exceed Its Designed Voltage Of 32 Volts
By Mike Mitchell

January 20, 2013 - The National Transportation Safety Board today released a third update on its investigation into the January 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston.

On January 7, a Japan Airlines (JAL) Boeing 787 battery overheated and started a fire at Boston's Logan International Airport. Japan’s transport-ministry investigator, Hideyo Kosugi said that in its preliminary investigation the battery indicated “voltage exceeding the design limit was applied”.

However, the NTSB has now reported an examination of the flight recorder data from the JAL B-787 airplane indicate that the APU battery did not exceed its designed voltage of 32 volts.

The lithium-ion battery that powered the auxiliary power unit has been examined in the NTSB Materials Laboratory in Washington. The battery was x-rayed and CT scans were generated of the assembled battery.


The investigative team had disassembled the APU battery into its eight individual cells for detailed examination and documentation. Three of the cells were selected for more detailed radiographic examination to view the interior of the cells prior to their disassembly. These cells are in the process now of being disassembled and the cell's internal components are being examined and documented.

Investigators have also examined several other components removed from the airplane, including wire bundles and battery management circuit boards. The team developed test plans for the various components removed from the aircraft, including the battery management unit (for the APU battery), the APU controller, the battery charger and the start power unit.

On Tuesday, the group will convene in Arizona to test and examine the battery charger and download nonvolatile memory from the APU controller. Several other components have been sent for download or examination to Boeing’s facility in Seattle and manufacturer’s facilities in Japan. Finally, examination of the flight recorder data from the JAL B-787 airplane indicate that the APU battery did not exceed its designed voltage of 32 volts.



On January 9, United Airlines reported a problem in one of its six 787s with the wiring in the same area as the battery fire on JAL's airliner; the U.S. National Transportation Safety Board subsequently opened a safety probe. 

On January 16, 2013, an All Nippon Airways 787 made an emergency landing at Takamatsu Airport on Shikoku Island after the flight crew received a computer warning that there was smoke inside one of the electrical compartments. ANA said that there was an error message in the cockpit citing a battery malfunction. Passengers and crew were evacuated using emergency slides. 

As a result of these battery issues and other issues the FAA issued an emergency airworthiness directive (AD) to address a potential battery fire risk in the 787. The AD requires operators to temporarily cease operations. Before further flight, operators of U.S.-registered, Boeing 787 aircraft must demonstrate to the Federal Aviation Administration (FAA) that the batteries are safe. 

United Airlines is currently the only U.S. airline operating the 787, with six airplanes in service. When the FAA issues an airworthiness directive, it also alerts the international aviation community to the action so other civil aviation authorities can take parallel action to cover the fleets operating in their own countries. As a result of this AD those countries that their airlines operate the Boeing 787 also grounded the 787. 

The 787 relies more than any other modern airliner on electricity to power nearly everything the plane does. It’s also the first Boeing plane to use rechargeable lithium-ion batteries for its main electrical system. These batteries are prone to overheating but have additional safeguards installed that are meant to control the problem and prevent fires.
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