Japanese probe finds miswiring of Boeing 787 battery

Bart Jansen, USA TODAY | AP

Japanese safety investigators said Wednesday they found improper wiring for a lithium-ion battery aboard an All Nippon Airways Boeing 787 Dreamliner that made an emergency landing in Japan last month.

U.S. safety investigators say they haven't found a similar wiring problem in the 787 battery that caught fire in a parked Japan Airlines plane in Boston.

Japan Transport Safety Board investigators said in an 18-page report that the tail and wing lights on the All Nippon plane flickered after it landed and the plane's main battery was switched off.

This suggested to investigators that an abnormal current was traveling from the auxiliary battery because of improper wiring. Investigators said more analysis was needed to determine what caused the main battery near the cockpit to overheat and emit the smoke that prompted the emergency landing Jan. 16.

Marc Birtel, a Boeing spokesman, said the company couldn't comment on the finding because it is part of the Japanese investigation.

The Boston fire occurred Jan. 7 in an auxiliary battery while maintenance crews worked on the plane. Regulators worldwide grounded the 50-plane fleet of Dreamliners as investigators search for the reason for the battery problems.

In the USA, the National Transportation Safety Board has traced the origin of the fire to one of eight cells in the battery. Investigators continue to search for the cause, which could be a charging problem, a manufacturing flaw or something else.

"We have not found issue with the wiring of our battery," says Kelly Nantel, a board spokeswoman. "However, our investigation is still ongoing."

Boeing used lithium-ion batteries in the Dreamliner because they weigh less than conventional batteries, charge faster and can produce more power than others of comparable size. They also are more likely to overheat and catch fire than conventional batteries.

Boeing, the first aircraft maker to use the batteries, has stopped deliveries of the sophisticated new planes to airlines until problems with the batteries are solved.

Airbus, Boeing's European rival, said last week it was scrapping plans to use lithium-ion batteries when it launches its new A350 next year. Airbus said it was going to use more conventional, albeit heavier, batteries after seeing the problems Boeing faced with them.

The A350 mirrors the Dreamliner in its billing as a more lightweight, fuel-efficient jet of the future.

Contributing: The Associated Press