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Japan Transportation Technology

Dreamliner: Boeing 787 Aircraft Battery "Not Faulty" 184

Posted by samzenpus
from the everything-checks-out dept.
SternisheFan writes "Airline safety inspectors have found no faults with the battery used on Boeing's 787 Dreamliner, Japan's transport ministry has said. The battery was initially considered the likely source of problems on 787s owned by two Japanese airlines. The world's entire fleet of 50 787s has been grounded while inspections are carried out. Attention has now shifted to the electrical system that monitors battery voltage, charging and temperature. Transport ministry official Shigeru Takano said 'we have found no major quality or technical problem' with the lithium-ion batteries. Shares in GS Yuasa, which makes the batteries, jumped 5% on the news. 'We are looking into affiliated parts makers,' he said. 'We are looking into possibilities.'"
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Dreamliner: Boeing 787 Aircraft Battery "Not Faulty"

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  • by ColdWetDog (752185) on Monday January 28, 2013 @01:54PM (#42717135) Homepage

    This [mpoweruk.com] is a nice quick review of Lithium nastiness....

  • by Anonymous Coward on Monday January 28, 2013 @02:06PM (#42717319)

    Actually it would not help. The nasty thing about these battery fires is the battery chemistry SUPPLIES OXYGEN.

  • by sjames (1099) on Monday January 28, 2013 @02:13PM (#42717435) Homepage

    On single cells, that protection is a small IC affixed to one end of the battery. In a battery pack, there is a protection circuit that covers the entire pack. For a battery bank, it's perfectly reasonable to combine the protection circuit with the charging system. In consumer goods where the battery isn't a user replaceable item, the protection is built in to the charging circuit. In any of those cases, a defect in the protection circuit can lead to a problem.

    In all of the above cases, the protection includes preventing over charge and over discharge (fatal to LiIon batteries).

  • Nuanced response (Score:5, Informative)

    by Okian Warrior (537106) on Monday January 28, 2013 @03:14PM (#42718255) Homepage Journal

    So what you're really saying is "Take the number of [batteries] in the field, A, multiply by the probable rate of failure, B, multiply by the average out-of-court settlement, C. A times B times C equals X. If X is less than the cost of a recall, we don't do one. "

    The actual answer is more nuanced.

    FAA regulations define 5 levels of critical for safety systems: levels A through E.

    Level A is for things that can knock a plane out of the sky when they fail; for example the stall speed alarm.
    Level C is for things that can cause injury or at most a single death; for example, the cabin pressurization system
    Level E is for things that don't affect flight safety; such as, in-flight entertainment or the microwave in the galley

    For reference, I wrote the software for cabin pressurization systems. It's level C (hardware == B), which means that failure in pressurization is an emergency situation, but isn't expected to kill everyone on board. The masks drop and the pilot immediately dives to under 10,000 feet to restore breathable air.

    If the cabin fills with smoke, it's not life-threatening per se. The pilot can override the pressurization system and "dump" the cabin atmosphere, and it clears pretty quick. (The captain also dives to under 10,000 feet if necessary.)

    The battery catching fire isn't a problem SO LONG AS the fire itself won't cripple the aircraft. The battery underpowering the plane when the alternator dies MAY BE a problem which would kill people.

    The people who design these things take these levels into consideration, and the general rule is "fail safe". If you can't "fail safe", then "fail in the least dangerous way". In my experience, the engineer must make many choices when designing an aircraft unit. The answer is always "do it *this* way, because if *that* happens it will be less dangerous.

    Let's wait and see what the investigation uncovers. Here are some Cliff notes:

    1) Li-Ion batteries might behave differently at altitude (cabin pressure is reduced while flying)
    2) The battery may be performing to spec, while trying to compensate for a more dangerous problem
    3) Smoke in the cabin is not as dangerous as you might think
    4) Things that burn are designed to not damage things when burning
    5) People who design aircraft are pretty smart, and have a generally high moral standard.
    6) People who investigate aircraft incidents are really, really thorough, and have a good track record.

    (Note: Glossing over some details to make an easier read.)

I am not now, nor have I ever been, a member of the demigodic party. -- Dennis Ritchie

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