Dreamliner battery maker under probe

US and Japanese aviation safety officials investigating problems with Boeing Co's 787 Dreamliner visited the headquarters of the plane's battery maker on Monday, seeking clues into why one of the technologically advanced aircraft made an emergency landing last week.

A spokesman for GS Yuasa Corp, which makes batteries for the 787, said the company was fully cooperating with the investigation, and its engineers were working with the officials from the US Federal Aviation Administration (FAA) and Japan's Civil Aviation Bureau (CAB) at the company's compound in Kyoto, where it makes airplane batteries.

CAB official Tatsuyuki Shimazu told reporters the investigating team had been briefed by GS Yuasa and had toured the plant, looking at battery design, production and quality. The Japanese investigation at the plant will continue on Tuesday on a more detailed level, including tracking battery batch numbers and production dates, he said.

Authorities around the world last week grounded the new lightweight aircraft, and Boeing halted deliveries after a problem with a lithium-ion battery prompted an All Nippon Airways 787 into the emergency landing at Takamatsu airport during a domestic flight. Earlier this month, a similar battery caught fire in a Japan Airlines' 787 parked at Boston Logan International Airport. US safety investigators on Sunday ruled out excess voltage as the cause of the Boston battery fire on January 7, and said they were expanding their probe to look at the battery's charger and the jet's auxiliary power unit.

"Results have shown the battery was abnormal in both the Boston and Takamatsu (incidents). They were the most damaged," Shigeru Takano, a senior safety official at the CAB, told reporters. Ahead of the on-site visit to GS Yuasa, Takano said: "We will look into if the work that took place, from design to manufacturing, was appropriate."

Shares in GS Yuasa, valued at close to $1.5 billion (£944.8 million), rose one per cent on Monday, having dropped nearly 10 per cent since the Boston fire.

The benchmark Nikkei was down 1.5 per cent. The company expects revenue of 288 billion yen (£2 billion) in the year to end-March — with only around 1 per cent of that coming from its aircraft battery business.

The company's batteries are used primarily in motorbikes, industrial equipment and power supply devices. GS Yuasa, in which automaker Toyota Motor Corp has a 2.7 per cent stake, reported an operating profit of around $160 million in the year to last March.

The battery is one part of the 787's complex electrical system, built by French company Thales SA.

More flights cancelled
The grounding of the Dreamliner, an advanced carbon-composite plane with a list price of $207 million, has forced ANA to cancel 141 flights between Wednesday and Sunday, affecting more than 18,000 passengers, the carrier said on Monday. Those cancellations added to the 72 flights scheduled for January 19-22 that ANA called off last week.

JAL also cancelled flights on its Tokyo-San Diego route for January 27-28.

Japan is the biggest market to date for the Dreamliner, with JAL and ANA flying 24 of the 50 passenger jets that Boeing has delivered.

ANA cancels 177 more flights

All Nippon Airways said on Monday it cancelled 151 domestic and 26 international flights scheduled for January 23-28 after Boeing Co's 787 Dreamliner passenger plane was grounded, affecting more than 21,000 passengers.

The cancellations add to the 72 flights scheduled for January 19-22 that ANA called off last week.

ANA, which flies the most Dreamliners of any airline, said in a statement it will announce on Thursday its plans on flight cancellations for dates from January 29.

Rival Japan Airlines Co said on Monday it will cancel four flights on its Tokyo-San Diego route for January 27-28, adding to the 8 flights originally scheduled for January 19-25 on the same route it called off last week.

Any schedule changes for flights slated for January 26 have yet to be decided, JAL added in a statement.

U.S. and Japanese aviation safety officials investigating the Dreamliner's recent battery-related incidents on Monday visited the Kyoto headquarters of GS Yuasa, the firm that makes batteries for the 787, seeking clues into why one of the planes made an emergency landing last week.

(Reporting by James Topham; Editing by Ken Wills and Ian Geoghegan)