WASHINGTON (Reuters) - U.S. officials on Friday said they are making progress in their investigation of a battery fire on a Boeing Co (BA.N) 787 Dreamliner in Boston this month, as the grounding of Boeing's entire fleet Of 787s stretched into a third week.
All 50 Boeing 787s remain grounded as authorities in the United States, Japan and France investigate the Boston battery fire on January 7 and a separate battery failure that forced a second 787 to make an emergency landing in Japan a week later.
The U.S. safety board said it continued to look at flight data recorded aboard the 787 aircraft involved in the January 7 event at Boston airport for any information about the performance of the lithium-ion battery that caught fire, and its charging system, which was built by Securaplane, a unit of Britain's Meggitt Plc (MGGT.L).
"Our investigators are moving swiftly and we are making progress," Kelly Nantel, a spokeswoman for the U.S. National Transportation Safety Board, said after the U.S. safety board issued a seventh update on the investigation. She did not elaborate.
Boeing welcomed the news and said it continued to work closely with authorities in the United States and Japan.
The NTSB said an expert from the Department of Energy had joined the investigation, and an NTSB investigator would travel to France on Sunday or Monday with a "battery contactor", which connects the battery to the planes' electrical systems, for further tests at the equipment's manufacturer, Thales SA (TCFP.PA).
The NTSB experts at the U.S. Naval Surface Warfare Center laboratories were continuing to look at a second, undamaged lithium-ion battery pulled from the same Japan Airlines (9201.T) plane. Both batteries were built by GS Yuasa (6674.T), a Japanese company.
Initial tests, including infrared thermal imaging of each cell in the undamaged battery, found no anomalies, according to the NTSB update. It said the battery's eight cells were undergoing another scan to examine their internal condition.
U.S., Japanese and French safety inspectors - aided by industry officials - have been trying to determine what caused the battery fire on the 787 in Boston and a separate battery failure in Japan that involved smoke the following week.
The failure of investigators to identify the root cause of the incidents has sparked concerns that the 787 grounding will last longer, and hit Boeing and the airlines that operate the 787 harder than expected.
But Boeing's chief executive, Jim McNerney, told investors this week that the company planned to speed up production of the jet as planned, and had not seen any reason to question its use of lithium ion batteries on the 787.
Boeing's shares closed 1.35 percent higher at $74.87 on the New York Stock Exchange on Tuesday.
Neither the NTSB, nor the U.S. Federal Aviation Administration, which is looking at a broader range of problems with the 787, have set timetables for completing their work.
Investigations are also continuing in Seattle, where Boeing builds the planes, and in Japan. (Reporting By Andrea Shalal-Esa; Editing by Leslie Gevirtz and Carol Bishopric)