Cold winter temperatures were a factor in the meltdown of a lithium ion battery that caused a Boeing 787 Dreamliner to make an emergency landing in Japan last year, the Asahi newspaper said, citing the conclusions of local investigators.
The battery meltdown on the ANA plane prompted authorities to ground the global fleet of 787s for more than three months.
It followed an incident less than two weeks earlier at Boston Airport when a battery on a parked Japan Airlines 787 overheated and emitted white gases.
Low temperatures can cause a lithium ion battery to deteriorate, resulting in the risk of a short circuit, Kyodo News reported separately. The battery is located in an unpressurised, unheated part of the plane.
The Japan Transport Safety Board plans to release a final report on its findings as early as September, the Asahi said, without citing sources.
A spokeswoman for accident investigators declined to comment on the report.
Boeing won approval for 787 flights to resume after it redesigned the battery compartment to isolate thermal events and vent hot gases outside the aircraft.