The Japan Transport Safety Board (JTSB) has concluded in a draft report that extreme cold most likely caused a lithium-ion battery on an All Nippon Airways Boeing 787 to malfunction in January 2013, The Asahi Shimbun newspaper reported. The board plans to release a final report in September or later.
The ANA 787 was flying from Yamaguchi-Ube Airport to Tokyo Haneda Airport when cockpit instrumentation indicated a battery malfunction and pilots made an emergency landing at Takamatsu Airport. The incident on January 16, 2013, was the last in a series of battery events that led the U.S., Japan and other aviation authorities to ground the 787 for some three months until they approved a battery-system modification.
Citing aviation sources, the newspaper said liquid electrolytes in the lithium-ion batteries were found to deteriorate at lower temperatures, resulting in reduced conductivity. Extreme coldness can also cause “lithium plating,” in which the metallic lithium dissolved in the battery’s electrolyte is deposited on the surface of electrodes and can lead to a short circuit.
In its final report, the JTSB “plans to conclude that the ‘smoking was not the result of a singular stimulant, but a combination of multiple causes,’” The Asahi Shimbun said on August 5.