Japanese and U.S. transportation officials went to Kyoto on Monday to inspect GS Yuasa Corp., which supplies lithium-ion batteries for Boeing Co.’s 787 Dreamliners, following the emergency landing of an All Nippon Airways Co. 787 last week that prompted the worldwide grounding of the jets, the transport ministry said.
The main Dreamliner battery, made by Kyoto-based GS Yuasa, is believed to have overcharged, causing smoke in the ANA 787 and prompting the Jan. 16 emergency landing at Takamatsu Airport in Kagawa Prefecture.
One official from the Land, Infrastructure, Transport and Tourism Ministry and two from the U.S. Federal Aviation Administration questioned GS Yuasa officials about the batteries’ design and production processes, the ministry said.
ANA said Monday the worldwide grounding of the Dreamliner forced it to cancel 335 domestic and international flights from Jan. 16 to next Sunday, affecting nearly 48,000 passengers.
On Sunday, the National Transportation Safety Board said the battery that caught fire in a Japan Airlines Boeing 787 in Boston earlier this month was not overcharged. But government investigators said there could still be problems with wiring or other charging components. That cell was located in an aft compartment along with an auxiliary power unit.
An examination of the flight data recorder indicated the battery didn’t exceed its designed voltage of 32 volts, the NTSB said.
NTSB investigators are continuing to look at the battery system. They plan to meet Tuesday with officials from Securaplane Technologies Inc., manufacturer of the charger for the batteries, at the company’s headquarters in Tucson, Arizona, said Kelly Nantel, a spokeswoman for the board.
“Potentially there could be some other charging issue,” Nantel said. “We’re not prepared to say there was no charging issue.”
Even though it appears the voltage limit wasn’t exceeded in the case of the JAL 787 battery that caught fire Jan. 7 in Boston, it’s possible the battery failures in that plane and in the ANA plane that made the emergency landing last week may be due to a charging problem, according to John Goglia, a former NTSB board member and aviation safety expert. The problematic battery in the ANA jet was a larger unit in an electrical bay under the cockpit.
Too much current flowing too fast into a battery can overwhelm the cell, causing it to short-circuit and overheat even if the battery’s voltage remains within its design limit, he said.
“The battery is like a big sponge,” Goglia said. “You can feed it with an eye dropper or you can feed it with a garden hose. If allowed, it will soak up everything it can from the garden hose until it destroys itself.”
There are so many redundancies and safeguards in aviation that when an accident or mishap occurs, it almost always is the result of a chain of events rather than a single failure, he said.