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Did Cold Weather Cause Boeing Battery Meltdown? Probably Not

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William K.
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Platinum
The news seldom knows, and we know that
William K.   8/15/2014 8:54:10 PM
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Most of the time the news media pundits are simply talking what they have heard from some convenient source, which may be a clueless individual or just a convenient individual with some possibly related credentials. Besides that there is a very definite slanting of most news stories to back that news groups personal agenda, which we very seldom are aware of. In addition everything has to be filtered by the legal dpartment, and then smoothed off so that it won't be excessively alarming to the general populace. 

So it is difficult to find much useful information from the news media. And the internet typically is a lot less accurate than that. At least, a lot of the internet sources are much less accurate, I suppose that the truth may be available someplace.

jpbennqc
User Rank
Iron
Re: Easier Solution?
jpbennqc   8/14/2014 6:02:10 PM
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The batteries are installed in the E&E compartments, which are very warm places to begin with. There is absolutely no need to heat the batteries. The main issue in the E&E compartments is trying to keep all the electronics cool, so much so that some equipment uses a liquid cooling system to keep the temperatures down.

jpbennqc
User Rank
Iron
Re: Too Close
jpbennqc   8/14/2014 5:58:01 PM
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Nope, not early... late... I'm second shift, so I'm typically burning the midnight oil. And that was ten million flight hours with the original design battery. The new design has better numbers. Installing the new design battery in a hermetically sealed stainless steel container improves things from a safety stand-point immeasurably. I can safely say this problem is behind us now. I'd worry more about all those Li-Ion batteries that are in everybodies' cell phones and laptops that are carried onboard...

Battar
User Rank
Platinum
Re: Too Close
Battar   8/14/2014 2:35:47 AM
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JP,

    You're up early. 10 million flight hours? Given a fleet of 1000 long range aircraft, that equates to a possible in-flight fire and potential consequent hull loss once every 4.3 years, which, unless you are flying with Malaysian Airlines, is unacceptable. Most airliners have a better safety record.

jpbennqc
User Rank
Iron
Re: Too Close
jpbennqc   8/14/2014 1:57:40 AM
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I must correct you... the 787, being constructed of carbon fiber, actually has a lower cabin altitude than the traditional aluminum build aircraft. At cruising altitude, the 787 has a cabin altitude of between 5000 to 6000 feet... basically the altitude of Denver, Colorado. But you are correct about the testing procedures for the Li-Ion batteries... too much reliance on information provided by the battery manufacturer during FAA certification, and not enough "pondering the imponderables"... it was estimated during initial certification that the likelihood of a battery failure like the type seen in both the JAL and ANA incidents was once every 10 million flight hours... so either someone's calculations were a little off, or we're good on the batteries for about the next 19 million flight hours.

Battar
User Rank
Platinum
Re: Too Close
Battar   8/14/2014 1:45:00 AM
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JPBennqc,

     As you well know, the pressurized part of a passenger aircraft is not at sea level pressure, but at 8000ft altitude equivalent pressure. The question raised in an earlier comment was, why didn't the failure mode get picked up in testing, if the systeme was tested in operational conditions? My suggestion was, perhaps the test conditions didn't replicate actual service conditions. NASA had a saying - "test as you fly, fly as you test". Maybe that mantra got dropped on the way.

jpbennqc
User Rank
Iron
Re: Too Close
jpbennqc   8/14/2014 1:04:44 AM
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No difficulty for me... I am an inspector assigned to the 787 program, and am speaking from actual knowledge on the subject. What I have described in my previous post is EXACTLY how the current 787 Li-Ion battery installations are configured. The original battery design had a flaw in it... the battery cells had no separation between them, and if one cell went into a thermal runaway condition, the heat generated in that failed cell spread into the adjacent cells, and caused thermal runaway in them as well, destroying the battery. That is why the new battery has separated and insulated the cells from one another. A much safer product.

a.saji
User Rank
Silver
Re: Too Close
a.saji   8/13/2014 11:34:40 PM
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@jpbennqc: Well there are so many definitions on this subject but what matters is what exactly the correct one. I know it will be difficult to figure out what's true and what's not but still the value of the correct one remains the same

jpbennqc
User Rank
Iron
Re: Too Close
jpbennqc   8/13/2014 11:16:45 PM
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OK, time to clear up some misconceptions. I had to do the same thing with Reuters and their article on the subject. Seems like everyone is relying on some erroneous information regarding where the Li-Ion batteries (there are two of them installed on the 787) are located on the aircraft. They are NOT installed in any unpressurized areas, and they are NOT installed in any unheated areas of the aircraft. The Main battery is installed in the forward electrical and electronics compartment (Fwd. E&E) and the Auxiliary Power Unit (APU) battery is installed in the aft E&E compartment. Both of these compartments are located within the aircraft pressure vessel, and as such, are in areas that are both pressurized and temperature controlled. If you have ever been in an aircraft E&E compartment, you would know that it gets kinda toasty in there. Cold isn't a problem, heat is. So applying heat to the batteries is highly unnecessary. Part of the redesign of the 787 Li-Ion battery system involved placing the batteries in sealed stainless steel containers, which vent overboard in case of any over-pressure events that would occur if a battery over-heats, and a redesign of the batteries themselves. The new design Li-Ion batteries have separated the battery cells inside, and insulated them from one another. In the event of a thermal runaway on one of the cells, the insulating materials will keep the heat away from the remaining cells. These changes have made the Li-Ion battery systems used on the 787 much more reliable and robust.

Trenth
User Rank
Gold
Re: Too Close
Trenth   8/13/2014 4:49:12 PM
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First of all, Boeing when with Varta instead of A123's inherently safer cell.

But even the A123 have been associated with fires, thought it's not clear the battery was the problem.  http://www.flightglobal.com/news/articles/cessna-stands-behind-lithium-ion-batteries-plans-roll-out-on-four-jets-after-381434/

These are much more powerful batteries than just ten years ago. Any mistake in the electronics can melt down violently, without a fault in the battery.  

The batteries and the electronics need to be well protected, and in fire proof enclosures.
Given the newness of these lithium batteries, we need battery black boxes, to determine exactly what the problems are, and much better testing.  
The articles still group all lithium batteries together, when they are vastly different.  


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