Probe shifts to monitoring system maker

The joint US and Japanese investigation into the Boeing 787's battery problems has shifted from the battery-maker to the manufacturer of a monitoring system. Japan transport ministry official Shigeru Takano today said that the probe into battery-maker GS Yuasa was over for now as no evidence was found it was the source of the problems.

Ministry officials said they will inspect Kanto Aircraft Instrument Co today as part of the ongoing investigation. It makes a system that monitors voltage, charging and temperature of the lithium-ion batteries. All 50 of the Boeing 787s in use around the world are grounded after one of the jets operated by All Nippon Airways made an emergency landing in Japan earlier this month when its main battery overheated.

Earlier in January, a battery in a Japan Airlines 787 caught fire while parked at Boston's Logan International Airport. GS Yuasa shares jumped on the news it is no longer being investigated, gaining nearly 5 per cent in Tokyo trading. The issue had plunged 12 per cent after the battery problems surfaced in Japan.

Ministry officials stopped short of saying that Kanto's monitoring system was under any special scrutiny, saying it was part of an ongoing investigation. "We are looking into affiliated parts makers," Takano said. "We are looking into possibilities." Kyoto-based GS Yuasa declined to comment, noting that the investigation was still underway. Deliveries of the jet dubbed the Dreamliner were three years behind schedule because of manufacturing delays. Much of the aircraft is made by outside manufacturers, many of them major Japanese companies who make about 35 per cent of the plane. It is the first jet to make wide use of lithium-ion batteries, the kind usually found in laptops and other gadgets. They are prone to overheating and require additional systems to avoid fires. Investigators have been looking at the remnants of the ANA flight's charred battery, but it is unclear whether the battery or a related part was behind its overheating. Investigators have said the ANA battery and the JAL battery did not receive excess voltage.