When a Cessna business jet equipped with lithium ion batteries caught fire in 2011 while it was hooked up to a ground power unit, Cessna and the Federal Aviation Administration moved swiftly to address the safety issues involved.
First the manufacturer advised owners of CJ4 aircraft to replace the lithium ion batteries in the plane with older technology nickel-cadmium or lead-acid batteries, and the FAA a few days later issued an airworthiness directive making those replacements mandatory.
Those jets were back in the air a few weeks later once the substitution was accomplished albeit equipped with heavier, less capable batteries.
The Cessna lithium battery fire foreshadowed problems now keeping Boeing’s newest airliner, the 787 Dreamliner, grounded after a different type of lithium battery sparked fires aboard Dreamliners in Boston and Japan in recent weeks.
Could Cessna’s reaction to its lithium battery problem provide Boeing a clue how to move forward?
First, the company says, it needs to find out what’s going wrong.
The National Transportation Safety Board, Boeing, the FAA and Japanese government investigators say they’re working ceaselessly to find out why the batteries failed. Fifty Dreamliners are not flying, and Boeing is delivering no more of the planes until the issue is solved. So far, there are no definitive answers.
The safety board said its first round of investigation found no evidence that the batteries in the Boston plane were overcharged, the most likely cause of the fire. Japanese investigators say they too have found no cause for believing the batteries in a Japan Air Lines plane that made an emergency landing there had lithium-ion batteries that were overcharged.
Initial dissection of the batteries shows there might have been a short circuit in one of the cells, but there is nothing definitive yet.
BOEING’S REPUTATION ON THE LINE
For Boeing and the airlines that bought the Dreamliner, finding answers quickly and restoring the Dreamliner’s safety and reputation are urgent priorities. The average list price for a Dreamliner is about $200 million, but airlines likely pay less. The groundings mean billions of dollars in capital assets aren’t earning their keep, and Boeing isn’t bringing in dollars for completed but undeliverable planes.
Boeing is keeping mostly mum about just exactly where their investigation is leading, about what its alternatives might be and how long clearing up the mystery and fixing it might take.
“We aren’t commenting on potential next steps until the investigation is over.” Boeing spokesman Doug Alder said Friday.
Most experts say solving the issue is likely to take weeks and perhaps months more.
Former NTSB member John Goglia told KIRO Radio on Friday that the investigation will likely be a long process.
“I’m afraid that if we don’t really find the root cause of this in the next week or two, we’re going to be looking at many, many months before this is resolved,” he said.
ASPECTS OF INVESTIGATION
Experts speculate the investigation is leading in several directions:
• Battery defects. Such high-power batteries are particularly sensitive to manufacturing flaws. Any foreign material could cause a short circuit inside the batteries causing the batteries to overheat and leading to the thermal overrun to spread to other cells. One cell in a battery involved in the Boston incident showed signs it might have short-circuited. The two planes involved in the two incidents were relatively new to commercial service.
The Japanese battery maker, GS Yuasa, says the batteries weren’t defective. Investigators have toured the company’s plant. They’ve made no pronouncements about whether the company’s products pass muster.
• Charging system problems. Boeing and government investigators are talking with the Arizona company, Securaplane Technologies, about its charging system. Overcharging the batteries could cause a fire. Again, there’s been no public verdict on whether the changing systems were working correctly, but the company has said it believes it is blameless.
• Monitoring and safety systems. The FAA allowed Cessna to pioneer the use of a different type of lithium-ion batteries in the CJ4 under a special set of conditions that required sophisticated control and monitoring systems for the batteries. Those elaborate safety systems were designed to prevent conditions that would upset the chemistry of the batteries and to isolate those batteries if they were failing. Special systems were designed to vent smoke and fumes should batteries catch fire. No fire suppression systems cover the lithium-ion batteries because putting out a fire in them is nearly impossible and they simply are allowed to burn out. When Boeing asked the FAA to use their lithium-ion batteries, the FAA crafted a set of special conditions similar to those it had imposed on Cessna.
In a news conference last week, the NTSB said those safety systems in the 787 had failed to operate as planned. That failure presents another issue for Boeing, Once it corrects the issues that caused the fire, the company must then address the safety systems’ defects.
Once Boeing and government investigators find and agree on the cause of the problems, then they’ll have to create solutions.
Experts say those solutions range from relatively simple to exceedingly complex.
• Correct battery or charger production defects. If the investigation leads to abnormalities in the assembly of the batteries or the charging systems, those contractors can take measures to ensure they don’t recur. The cathodes and anodes in lithium-ion batteries can grow “whiskers” if improperly made causing short circuits, said one expert. Improved manufacturing techniques will likely be paired with more extensive testing of the batteries and charging systems before they’re installed.
n Switch to alternate technology batteries. The batteries Boeing used in the Dreamliner are a variety called lithium-cobalt batteries. The company could substitute lithium-iron-phosphate batteries that some battery experts say are more tolerant to mistreatment and which are less likely to develop thermal overruns.
The planemaker could abandon lithium-ion batteries entirely, returning to nickel–cadmium or lead-acid batteries. The company’s 777 jetliner, part of which is made in Frederickson along with a part of the Dreamliner, and its newest version of the 747, the 747-8, use nickel–cadmium batteries.
Gulfstream Aerospace considered using lithium-ion batteries in its newest business jet, said Steve Cass, a Gulfstream spokesman. But the company decided to use the tried-and-true nickel–cadmium batteries instead. Those planes, however, don’t use electric architecture pioneered by the 787.
The Dreamliner uses electric motors to power most of the aircraft systems instead of the high-pressure air bled from the engines of those older-generation jets. The electric systems are more efficient and require less piping and ducting than the bleed air systems. But the 787’s electrical systems must be equipped to provide three or four times the power used in the older aircraft.
Weight is a problem with the older batteries. The two lithium battery packs in the 787, one near the front electronics bay and the other located nearer the plane’s tail, weigh 63 pounds each. A comparable nickel–cadmium battery might weigh 35 percent more. Substituting a different kind of battery isn’t likely to be a simple swap, said University of Washington chemistry professor Eric Stuve.
“These planes are designed around a lithium-ion battery,” he said. “Changing to another type of battery could mean redesign and retesting of the electrical system,” he said. “It would be like converting your car from a gasoline to a diesel engine.”
Lithium-ion batteries have been implicated in multiple incidents in aviation and in consumer use in recent years. Computer makers recalled thousands of laptop batteries because of overheating issues. The FAA has banned the carriage of loose nonrechargeable lithium-ion batteries in checked luggage on airliners. And lithium batteries are suspects in the crash of a UPS 747 cargo plane in Dubai in 2010.
But some planemakers say lithium-ion’s advantages in weight and power storage ability are good reasons to advance the art. The key, they say, is learning to manage the batteries’ disadvantages.
Cessna, which originally banned lithium batteries from its aircraft, this week said it intends to offer lithium batteries in several of its executive jets soon.John Gillie: 253-597-8663 firstname.lastname@example.org