Excess voltage of the 787 batteries is ruled out as the cause of the Boston JAL fire, NTSB now looking at the APU
The National Transportation Safety Board (NTSB) (Washington) has ruled out excess voltage as the cause of a battery fire this month on a Boeing 787 operated by Japan Airlines (Tokyo) according to Reuters (see reports below) and said they were expanding the probe to look at the battery’s charger and the jet’s auxiliary power unit.
According to the report, investigators will convene in Tucson, Arizona today to test and examine the charger for the battery, and download non-volatile memory from the APU controller, with similar tests planned at the Phoenix facility where the APUs are built.
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On January 14 the NTSB issued this preliminary report:
The National Transportation Safety Board today released a second update on its investigation into the Jan. 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston.
The lithium-ion battery that powered the auxiliary power unit on the airplane was removed and transported back to the NTSB Materials Laboratory in Washington on Jan. 10. The battery is currently being examined by NTSB investigators, who plan to disassemble it this week.
In advance of that work, under the direction of the NTSB, radiographic examinations of the incident battery and an exemplar battery were conducted this past weekend at an independent test facility. The digital radiographs and computed tomography scans generated from this examination allowed the team to document the internal condition of the battery prior to disassembling it.
In addition, investigators took possession of burned wire bundles, the APU battery charger, and several memory modules. The maintenance and APU controller memory modules will be downloaded to obtain any available data. Investigators also documented the entire aft electronics bay including the APU battery and the nearby affected structure where components and wire bundles were located. The airplane was released back to Japan Airlines on Jan. 10.
The airplane’s two combined flight data recorder and cockpit voice recorder units were transported to NTSB headquarters and have been successfully downloaded. The information is currently being analyzed by the investigative team.
The airport emergency response group documented the airport rescue and firefighting efforts to extinguish the fire, which included interviews with first responders. Fire and rescue personnel were able to contain the fire using a clean agent (Halotron), however, they reported experiencing difficulty accessing the battery for removal during extinguishing efforts. All fire and rescue personnel responding to the incident had previously received aircraft familiarization training on the Boeing 787. In accordance with international investigative treaties, the Japan Transport Safety Board and French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile have appointed accredited representatives to the investigation. The NTSB-led investigative team is comprised of subject matter groups in the areas of airplane systems, fire, airport emergency response, and data recorders and includes experts from the Federal Aviation Administration, The Boeing Company, US Naval Surface Warfare Center’s Carderock Division, Japan Airlines (aircraft operator), GS Yuasa (battery manufacturer), and Thales Avionics Electrical Systems (APU battery/charger system).
On January 20 the NTSB issued this on-going report:
The National Transportation Safety Board today released a third update on its investigation into the Jan. 7 fire aboard a Japan Airlines Boeing 787 at Logan International Airport in Boston.
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 has 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 has 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.
In accordance with international investigative treaties, the Japan Transport Safety Board and French Bureau d’Enquêtes et d’Analyses pour la sécurité de l’aviation civile have appointed accredited representatives to this investigation. Similarly, the NTSB has assigned an accredited representative to assist with the JTSB’s investigation of the Jan. 15 battery incident involving an All Nippon Airways B-787. Both investigations remain ongoing.