Toru Hanai/Reuters
All Nippon Airways, the biggest operator of 787s, is holding jets at Haneda airport in Tokyo.
Even before two battery failures led to the grounding of all Boeing 787 jets this month, the lithium-ion batteries used on the aircraft had experienced multiple problems that raised questions about their reliability.
Officials at All Nippon Airways, the jets’ biggest operator, said in an interview on Tuesday that it replaced 10 of the batteries in the months before fire in one plane and smoke in another led regulators around the world to ground the jets.
The airline said it told Boeing of the replacements as they occurred but was not required to report them to safety regulators because they were not considered a safety issue and no flights were canceled or delayed.
National Transportation Safety Board officials said Tuesday that their inquiry would include the replacements.
The airline also, for the first time, explained the extent of the previous problems, which underscore the volatile nature of the batteries and add to concerns over whether Boeing and other plane manufacturers will be able to use the batteries safely.
In five of the 10 replacements, All Nippon said that the main battery had showed an unexpectedly low charge. An unexpected drop in a 787’s main battery also occurred on the All Nippon flight that had to make an emergency landing in Japan on Jan. 16.
The airline also revealed that in three instances, the main battery had failed to start normally and had had to be replaced, along with the charger. In other cases, one battery showed an error reading and another, used to start the auxiliary power unit, failed. All of the events occurred from May to December of last year. The malfunctioning batteries, made by the Japanese manufacturer GS Yuasa, were serviced by All Nippon maintenance crew members. (The battery from the plane involved in the emergency landing was sent back to GS Yuasa.)
Japan Airlines, which operates seven 787s, said Wednesday that there had been “several cases” in which maintenance crew members needed to replace 787 batteries after irregularities, but the carrier declined to give details. The switches were not considered a safety risk and were conducted “within the scope of regular maintenance,” said Kazunori Kidosaki, a company spokesman.
Kelly Nantel, a spokeswoman for the National Transportation Safety Board, said investigators had only recently heard that there had been “numerous issues with the use of these batteries” on 787s. She said the board had asked Boeing, All Nippon and other airlines for information about the problems.
“That will absolutely be part of the investigation,” she said.
Boeing, based in Chicago, has said repeatedly that any problems with the batteries can be contained without threatening the planes and their passengers.
Boeing officials said the need to replace the batteries also suggested that safeguards were activated to prevent overheating and keep the drained batteries from being recharged. Company officials said the batteries can drain too deeply if left on without being connected to power sources. Trying to recharge such batteries could generate excessive heat, so safety mechanisms lock out any attempts to do that.
Boeing officials said that improperly connecting a battery can also render it unusable. And they acknowledged that some of the new batteries were not lasting as long as intended. They said that could cause airlines to replace them more frequently but did not pose a safety problem.
A GS Yuasa official, Tsutomu Nishijima, said battery exchanges were part of the normal operations of a plane but would not comment further.
The Federal Aviation Administration decided in 2007 to allow Boeing to use the lithium-ion batteries instead of older, more stable types as long as it took safety measures to prevent or contain a fire. But once Boeing put in those safeguards, it did not revisit its basic design even as more evidence surfaced of the risks involved, regulators said.
This article has been revised to reflect the following correction:
Correction: January 30, 2013
An earlier version of this article misstated the action taken by All Nippon Airways with 10 lithium-ion batteries it replaced on Boeing 787 jets between May and December of last year. The malfunctioning batteries were sent to the airline’s maintenance department for service, not to the maker, GS Yuasa. (The battery from the plane involved in an emergency landing earlier this month was, however, sent back to GS Yuasa.)
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