Boeing Aware of Battery Ills Before the Fires
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 had replaced 10 of the batteries in the months before fire and smoke in two cases caused 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 no flights were canceled. National Transportation Safety Board officials said Tuesday that the battery replacements were now part of their inquiry.
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 about whether Boeing and other plane manufacturers will be able to use the batteries safely.
(Read More: Japan Eased Safety Standards Ahead of 787 Rollout)
In five of the 10 replacements, All Nippon said that the main battery 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 January 16.
The airline also revealed that in three instances, the main battery failed to start normally and 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 the events occurred from May to December of last year. And all the batteries were returned to their maker, GS Yuasa.
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 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.
But in response to All Nippon's disclosures, Boeing officials said the airline's replacement of the batteries also suggested that safeguards to prevent dangerous overheating of the batteries might have kicked in.
Boeing officials also acknowledged that the new batteries were not lasting as long as they were meant to. But All Nippon said that the batteries it replaced had not expired.
(Read More: Boeing Battery Fires Cast Doubt on Feds' Oversight)
A GS Yuasa official, Tsutomu Nishijima, said battery exchanges are 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 that type of battery provided the most power, but could also overheat more quickly.
And 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 January 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 when pilots smelled smoke in the cockpit.
Federal regulators said it was also still possible that flaws in the manufacturing process could have gone undetected and triggered the recent incidents.
The batteries' maker X-rays each battery before shipping them to look for possible defects.
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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. For that reason, it is now widely used in personal electronics and is finding greater acceptance in other industries, like electrical cars.
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 little choice than picking more traditional battery designs to restore confidence in its airplanes.
Switching batteries would come at a steep cost, and would 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 potential dangers 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.
(Read More: Shift in Boeing Probe Away From Battery to Monitor)
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 incident, 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 excessive heat and 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 catch fire 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.
(Read More: Whistleblower Says Dreamliner Batteries Could 'Explode')
A Cessna spokesman declined to comment about the incident.
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 funny smell. Right about then, sensors detected a sudden unstable discharge of the battery to near zero for reasons that Japanese investigators still cannot explain.
