The executive, W. James McNerney Jr., acknowledged that some airlines had needed to replace the new batteries at a “slightly higher” rate than Boeing had expected. But he also said that the replacements were related to maintenance issues rather than safety concerns.
Mr. McNerney made the comments in a conference call to discuss the company’s financial performance.
They came a day after All Nippon Airways, which operates 17 of the new jets, said it had replaced 10 batteries from May through December last year. The New York Times reported earlier on Wednesday that federal regulators planned to expand their investigation of a recent fire on one 787 and a smoldering battery on another to seek information about why the 10 batteries had been replaced.
All Nippon had told The Times that it replaced the batteries after they showed unexpectedly low charges or failed to operate normally. Boeing officials have said that maintenance problems could include faster-than-expected aging, or errors by mechanics in improperly disconnecting the batteries or letting them drain too far.
“What we know is that the replacement cycle that we’ve been experiencing there has been for maintenance reasons,” Mr. McNerney said. “There is no incident where we’re aware of where a battery has been replaced due to any kind of safety concerns.”
Boeing officials also said that some of the batteries might have needed replacing because built-in safeguards had activated to prevent overheating and to keep the drained batteries from being recharged in a risky manner. Boeing said that if mechanics had improperly connected a battery, another safeguard would also render the battery unusable.
Mr. McNerney said he would not speculate on how long it would take to determine the cause of the battery smoke and fire on the two 787s and how much it would cost the company to fix the problems.
Aviation analysts have said the worst case could involve Boeing switching back to older and less volatile battery technologies, like nickel-cadmium, to restore confidence among air travelers.
But Mr. McNerney said, “Nothing we’ve learned has told us that we made the wrong choice on the battery technology.” He added a moment later that none of the investigative findings “causes us to question that decision at this stage.”
Investigators for the National Transportation Safety Board and their Japanese counterparts have said they have not found anything that could explain the two incidents on the planes.
Battery experts said they could understand why investigators would want to closely review information about how the batteries have performed on all 50 787s delivered so far and why some were replaced.
“Everybody is in favor of safeguards,” said Donald R. Sadoway, a professor of material chemistry at the Massachusetts Institute of Technology. “And the batteries could be fine as manufactured, and tested and perform in excess of specifications.
“But in service they could develop some weakness,” he added. “That’s hard to find out. That’s dynamics. That’s like looking at the grapes and trying to find out what the wine will taste like.”
Ralph J. Brodd, a battery industry consultant in Henderson, Nev., said lithium-ion batteries needed safeguards in cases where they were discharged too completely because materials inside the batteries are more flammable than in nickel-cadmium batteries, which contain water that can prevent overheating.
Since the 787s are the first Boeing planes that use the new technology, he said it would prudent for the airline to replace batteries about which it had concerns.
Separately on Wednesday, Japanese investigators who inspected Kanto Aircraft Instrument, the manufacturer of a unit that monitors the lithium-ion batteries, told reporters that they had advised the company to make “several improvements on quality assurance” but had found “nothing that appeared related to the recent problems.”
Jad Mouawad and Hiroko Tabuchi contributed reporting.
Article source: http://www.nytimes.com/2013/01/31/business/boeing-earnings-exceed-estimates.html?partner=rss&emc=rss