Overcharging batteries eyed in Boeing 787 mishaps

WASHINGTON (AP )-
Aviation safety and battery experts said on Friday that lithium-ion batteries on two Boeing 787 Dreamliners may have been caused by excessive charging, pointing out the progress of the Boeing incident investigation, and the battery of a business plane caught fire a year ago.
An investigator in Japan said the plane\'s lithium-ion battery was burnt inside, showing that the voltage received by the battery exceeded the design limit. An emergency landing of 787 aircraft earlier this week.
The batteries burned on all Japanese Airlines flights are similar to those burned out of 787 of the Japanese airlines that caught fire on January.
Koyo Kosugi, a Japanese Ministry of Transport investigator, said that when the plane stopped at Boston Logan International Airport, it showed a common cause.
\"If we compare the latest cases here with the United StatesS.
\"We can almost figure out what\'s going on,\" Kosugi said . \".
In the case of 787 in Boston, the battery in the aircraft auxiliary power unit recently received a lot of demand for its power, and when the fire was ignited, it was charging, A source familiar with the Boston 787 fire investigation told The Associated Press.
While a cleaner was working on the plane, the plane landed for a short time earlier, with no passengers.
The source requested anonymity because he was not authorized to speak publicly.
On Wednesday, the FAA issued an emergency order to temporarily close six 787 United Airlines aircraft. S.
The airline that operates Boeing\'s latest, state-of-the-art passenger aircraft.
Japanese airlines have suspended 787 flights, and airlines and civil aviation authorities in other countries have followed suit by shutting down all 50 Dreamliners Boeing has delivered so far.
Boeing said on Friday it will stop delivering the new 787 to its customers before the electrical system is repaired.
However, production did not stop.
The plane was gathered in Everett, washed.
And North Charleston, United States of AmericaC.
The aircraft manufacturer has booked orders for more than 800 aircraft from airlines around the world, which are attracted by improved fuel efficiency.
The fire on the battery of a commercial aircraft Cessna Citation 4 prompted the Federal Aviation Administration to issue an emergency order on October 2011, requiring all 42 jets running at that time to have lithium-ion batteries replaced with traditional nickel-Lead or cadmiumacid battery.
At the time of the fire, the plane was connected to a ground power station at the completion center of the wichtocessna aircraft in Kansas.
Typically, this will cause the aircraft battery to start charging automatically, experts say.
A letter from Cessna to the owner of the CJ4 after the accident warned: \"If you have reason to believe that the battery is likely to be exhausted, do not connect the ground power supply to the aircraft. . .
When connecting the ground power supply device, do not leave the aircraft unattended.
\"This is Cessna\'s first business aircraft with lithium-ion batteries as its main battery, and 787 is the first aircraft to use lithium-ion batteries extensively.
But the two are very different in size and other aspects, including their electrical systems, which makes it difficult to compare.
Their batteries also come from different manufacturers.
Experts say they may have different reasons for overcharging.
However, these three incidents
The two burned 787 batteries and fired-
Experts say it is emphasized that lithium-ion batteries are prone to fire when the voltage is too high and too fast.
Other types of batteries may overheat in this case, they say, but they are not too easy to catch fire.
\"They don\'t go wrong when you\'re so bad about other batteries,\" said Jay Whitacre, associate professor of materials science and engineering at Carnegie Mellon University.
\"The overall situation here is that these batteries are full of flammable electrolyte and they burn if they are abused and there is a problem.
\"When Boeing cooperated with the FAA to certify 787, a lithium-ion battery fire occurred during the battery test,\" said Marc Birtel, spokesman for the aircraft manufacturer.
However, he said the fire was due to a test problem, not the battery itself.
\"To ensure system security, there are multiple backups,\" Birtel said . \".
\"These measures include preventing excessive
Charging and over-chargingdischarging.
\"But aviation safety experts, former National Transportation Safety Board member John gorlia, said,\" it certainly sounds based on the news that has been released so far, we are having problems with battery chargers or other sources that provide too much energy for the battery. \"He said too-
Fast charging can cause the electrolyte fluid in the battery to overheat, leak and catch fire.
If these incidents were caused by excessive battery charging, it could be good news for Boeing, Goglia said.
He said that a defect in aircraft electronics that allows excessive charging may be much easier than replacing the lithium battery of the aircraft with another battery.
Another possibility, Whitacre says, is the manufacturing defect of the battery itself.
Lithium-ion batteries rely more on very thin materials inside than other types of batteries to separate the negative and positive poles.
Minor defects can lead to short circuit, overheating flammable electrolyte.
\"This is a delicate ecosystem, you are creating it internally, and you have to make it with perfect integrity,\" Whitacre said . \".
\"Then you have to keep it within the correct voltage range and it is very safe under ambient conditions.
Jim mcnani, Chairman, President and CEO of Boeing, sent a letter to the company\'s employees on Friday expressing confidence in 787 and vowed to return the plane.
\"I am very proud of the company\'s employees in their ten-year efforts to design, develop, build and deliver the most innovative commercial aircraft ever,\" he said . \".
The attraction of the lithium battery is that it is much lighter than other types of batteries.
Fuel savings are a major expense for airlines.
Faster charging and more energy.
They can be shaped into odd spaces that fit on the plane, something that most other batteries can\'t do.
The only passenger aircraft using lithium batteries is the Airbus A380, which only has limited use of emergency lighting batteries.
However, Airbus is developing another A350 aircraft that is expected to debut in 2014, which will make lithium batteries more widely used.
Safety experts say Boeing\'s headaches for 78 7 lithium batteries could lead to more careful research by European security officials and other regulators around the world on the batteries of the new Airbus aircraft.
\"I think they\'re going to gain learning experience here, which could lead to changes in the future for anyone who wants to design a plane and use this battery technology,\" said Robert Figer, president of aviation science at embry.
It is located at the University of rider Aviation in azprescott.
The FAA, like aviation regulators in other countries, relies on aircraft manufacturers to test their aircraft to ensure their safety.
The certification engineer at FAA verified the test and ensured that the safety level was in compliance with the FAA regulations.
Boeing has developed safeguards for 787 lithium batteries, but they must first be approved by the FAA.
787-safety certification for design, manufacturer and assembly
A process that requires FAA approval for each step-
In some ways it is different from other planes because Dreamliner uses so many cuts
Security experts say this is a cutting-edge technology.
In addition to the use of lithium batteries, the 787 is the first passenger plane with a structure mainly made of composite materials rather than aluminum.
Compared to previous passenger planes, aircraft also rely more on electronic equipment to operate than hydraulic or mechanical systems.
\"You can make a list of the hardware on that plane, and this is the first time you use the hardware on the plane,\" said Saint Paul czsz, honorary retired professor of aviation engineering at St.
University of St. Louis. Louis.
\"For anything brand new and never used on a plane before, you have the potential to be the first to find out if it really works.
\"787 conducted extensive testing before and after the first test flight in 2009.
The FAA said its technical experts recorded 200,000 hours of testing and reviewing aircraft designs before they were certified in August 2011.
Six test flights took about 4,645 hours.
The agency said in 2011 that about 25 of these hours were flown by FAA flight testers.
AP Writer Malcolm Foster in Tokyo and Joshua Fried in Minneapolis contributed to the report.