U.S. investigators probing battery faults aboard a Boeing Co. 787 Dreamliner are asking for data on the performance of the devices after All Nippon Airways Co. said it had replaced 10 of the systems on its planes.
ANA changed lithium-ion batteries or chargers on its fleet of 787s prior to a Jan. 16 incident, in which one of the batteries smoldered and emitted smoke, prompting an emergency landing, Megumi Tezuka, an airline spokeswoman, said in an interview today. Boeing is aware that some Dreamliner batteries were replaced, said Marc Birtel, a company spokesman.
The U.S. National Transportation Safety Board is working with Chicago-based Boeing, which releases earnings Wednesday, to study the batteries’ history since the 787 entered service late in 2011, according to an e-mailed release by the investigative agency. The global fleet of about 50 Dreamliners has remained grounded since that emergency landing.
“As a party contributing to the investigation, Boeing is providing pertinent fleet information, which will help investigators understand the operating history of lithium-ion batteries on those airplanes,” the NTSB said Tuesday in its sixth update on the investigation.
Tokyo-based ANA was the first customer for the 787, which uses new technology such as carbon-fiber materials to save weight and improve efficiency. The plane was the first to use large lithium-ion batteries for backup power and to start the plane’s auxiliary power unit, a turbine engine that drives a generator mainly for power on the ground.
The previous battery problems didn’t cause cancelations or delays, and therefore weren’t reported to the ministry, Tezuka said.
Boeing couldn’t comment on customers that replaced batteries in service, Birtel said in an e-mail. The main reasons that batteries have failed on planes are a deep discharge that makes it impossible to recharge, an expired lifespan or an improper disconnection that renders a battery unusable, he said.
U.S. investigators are putting evidence under microscopes as they also look globally for patterns of flaws with the plane’s lithium batteries, the agency said in an e-mailed update Tuesday.
The broadening NTSB probe shows the board’s “methodical” work, as Chairman Deborah Hersman has termed it, won’t lead to an end to the 787’s grounding any time soon. Flights on Chicago- based Boeing’s most advanced jet were stopped by the Federal Aviation Administration and other aviation authorities Jan. 16, in the first such U.S. action involving an entire aircraft type since 1979, after a battery smoldered and emitted fumes on an ANA domestic flight in Japan.
The NTSB at that time was investigating a fire aboard a Japan Airlines Co. 787 after it landed in Boston.
Under the FAA’s order, the Dreamliner won’t fly until Boeing and airlines can show the batteries are safe. The agency is also reviewing the plane’s certification and manufacture, including its own 2007 decision allowing Boeing to use lithium batteries in the plane’s design.
The NTSB, which is assisting Japan’s investigation into the ANA incident, hasn’t been able to identify what caused the failures.
Investigators are still attempting to determine whether a common manufacturing error could have led to the failures even though the two batteries were made 10 months apart, according to two people familiar with the investigation. They asked not to be identified because they weren’t authorized to speak about the probe.
The board hasn’t ruled out potential causes ranging from damage during operations to a circuitry failure, the people said.
The battery that burned on the ANA plane was a replacement unit made in November 2011 and installed in October 2012 after an unspecified failure, according to Japan’s Transport Ministry and ANA.
The unit on the JAL plane was made in September 2012, according to the NTSB and Japan’s Transport Ministry. The batteries were made by GS Yuasa Corp., based in Kyoto.
Teams of NTSB specialists are examining with microscopes the battery that failed, and performing chemical analysis in the areas where they found internal short circuiting and thermal damage, according to its release.
The safety board is also scanning data contained on the JAL plane’s two flight-data recorders.