Japan's All Nippon Airways (ANA) has revealed it had repeatedly replaced the batteries even before overheating problems surfaced on the 787 Dreamliners, prompting US regulators to ask Boeing to provide a full operating history of the lithium-ion batteries used in the grounded fleet.
US National Transportation Safety Board (NTSB) spokesman Peter Knudson said the agency made the request after recently becoming aware of battery problems at ANA that occurred before a January 7 battery fire in a 787 parked at Boston's Logan International Airport. Boeing has already collected some of the information, he said.
ANA said it had replaced batteries on its 787 aircraft some 10 times because they failed to charge properly or showed other problems, and informed Boeing about the swaps. Japan Airlines also said it had replaced 787 batteries. It described the number involved as a few but couldn't immediately give further details.
All 50 of the Boeing 787s in use around the world remain grounded after an ANA flight on January 16 made an emergency landing in Japan when its main battery overheated.
Lithium-ion batteries are prone to overheating and require additional safeguards to prevent fires. However, ANA spokeswoman Megumi Tezuka said the airline was not required to report the battery replacements to Japan's Transport Ministry because they did not interfere with flights and did not raise safety concerns.
On Tuesday, the NTSB said it was conducting a chemical analysis of internal short circuiting and thermal damage of the battery that caught fire in Boston.
The probe is also analysing data from flight data recorders on the aircraft, the NTSB said in a statement on its website.
Meanwhile, Tech entrepreneur Elon Musk, founder of the electric carmaker Tesla and aeronautics firm SpaceX, has offered to help Boeing fix apparent problems with the batteries in its grounded 787 Dreamliner.
Spokeswomen from both of Musk's companies confirmed that he has reached out to Boeing, which has been struggling to address the concerns of customers and regulators following recent fire incidents that grounded the fleet.
"Elon has offered to help Boeing. Any further information about the offer will be left to Boeing and the FAA to communicate," SpaceX spokeswoman Emily Shanklin said, confirming messages posted by Musk on Twitter.
Boeing spokesman Marc Birtel confirmed the aircraft giant was "engaged with a number of experts, both inside and outside the company, in resolving the issue and returning the 787 fleet to flight status.
"However we are not identifying them by name publicly," he added.