From The New York Times
By CHRISTOPHER DREW, HIROKO TABUCHI and JAD MOUAWAD
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.
In a little-noticed test in 2010, the F.A.A. found that the kind of lithium-ion chemistry that Boeing planned to use – lithium cobalt – was the most flammable of several possible types. The test found that batteries of that type provided the most power, but could also overheat more quickly.
In 2011, a lithium-ion battery on a Cessna business jet started smoking while it was being charged, prompting Cessna to switch to traditional nickel-cadmium batteries.
The safety board said Tuesday that it had still not determined what caused a fire on Jan. 7 on a Japan Airlines 787 that was parked at Logan Airport in Boston. The fire occurred nine days before an All Nippon jet made its emergency landing after pilots smelled smoke in the cockpit.
Federal regulators said it was also possible that flaws in the manufacturing process could have gone undetected and caused the recent incidents.
The batteries’ maker X-rays each battery before shipping to look for possible defects.
But some battery experts said that scans might be unable to detect minute anomalies in the battery, like trapped micro-shavings in any of the tightly wound conductive material used in each battery’s eight cells.
So far, Boeing appears reluctant to consider alternatives. Lithium-ion, experts say, is particularly attractive because it packs more power in a smaller size, and is therefore lighter than more traditional battery designs – a factor that was part of Boeing’s strategy to build a lighter aircraft. Also for that reason, it is now widely used in personal electronics and is finding greater acceptance in other industries.
But unless investigators can point out the precise cause of the 787’s battery problems or how to prevent them, some experts believe Boeing may have little choice than to pick more traditional battery designs to restore confidence in its airplanes.
Switching batteries would come at a steep cost, and would most likely entail months of engineering work as well as new certification by regulators. It would also go against the efforts by other manufacturers, including Airbus and Gulfstream, to adopt lithium-ion batteries in airplanes.
Regulators have long known about the risks of lithium-ion batteries, which can overheat and ignite – a condition known as thermal runaway – if improperly charged or discharged. For that reason, the batteries are integrated into a sophisticated electronic system that is intended to monitor the battery and prevent it from overcharging.
The F.A.A.’s battery tests in 2010 highlighted the hazards of lithium cobalt batteries. When they overheat, the batteries showed “much more severe increases in temperature and pressure” than other battery types.
Another risk of lithium batteries also became apparent with the Cessna episode in 2011, when a technician working on a new model plane, the CJ4, hooked up the plane to a power source to recharge the battery and soon after saw smoke coming out of it.
According to a government safety official with knowledge of the episode, the Cessna battery had drained below 5 percent of its charge. The problem with lithium batteries, however, is that recharging a battery that has been drained to a low point can create a risk of fire because the battery is unable to accept a charge. Recharging it then creates heat that can cause it to ignite.
But after discussions with the F.A.A., Cessna decided to replace the battery on its planes with nickel cadmium batteries, which are heavier, but do not ignite easily. Boeing has said its system has safeguards that prevent a drained battery from being recharged without first being sent back to the manufacturer for reconditioning.
A Cessna spokesman declined to comment about the episode.
According to investigators in Japan, the battery on the jet that made the emergency landing showed a stable reading of 31 volts, near its full charge capacity, until 15 minutes into the flight when pilots detected a strange smell. About that time, sensors detected a sudden unstable discharge of the battery to near zero for reasons that Japanese investigators still cannot explain.
Matthew L. Wald contributed reporting.
This article has been revised to reflect the following correction:
Correction: January 31, 2013
An article on Wednesday about problems with the lithium-ion batteries used in Boeing ‘s 787 jet misstated, in some editions, the action All Nippon Airways took with 10 batteries it replaced on 787 jets between May and December 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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