Boeing’s Flaming Batteries Fixed? Where’s The Proof?

boeing2“Boeing’s fix includes more insulation between each of the eight cells in the batteries. The batteries will also be encased in a new steel box designed to contain any fire and vent possible smoke or hazardous gases out of the planes.

“…both the F.A.A. administrator, Michael P. Huerta, and Transportation Secretary Ray LaHood said they were are satisfied that the proposed changes would eliminate concerns that the plane’s two lithium-ion batteries could erupt in smoke or fire.”
-“F.A.A. Endorses Boeing Remedy for 787 Battery” by C. Drew and J. Mouawad, 19 April 2013 New York Times

Conspicuously absent from this pronouncement is a definitive identification of the root cause of the lithium battery fires. Therefore Boeing, the FAA, and the Department of Transportation are all guessing that the stated modifications will fix the problem. I hope they are correct. But if they are it will be a matter of luck, not engineering diligence. The dissembling of the FAA and Department of Transportation are clearly evident in their own words: they say that they are “…satisfied that the proposed changes would eliminate concerns that the plane’s two lithium-ion batteries could erupt in smoke or fire.” If they are so satisfied, then why is it necessary to have a steel box to contain a fire? If they are so satisfied, then why did they not provide the supporting evidence to support their conclusions?

Also, Boeing and these government agencies have touted a few test flights as being of particular significance in proving the safety of the batteries. This is nonsense. The battery fires are low probability events, occurring only once for thousands of hours of operation. This implies that there are subtle variables in the battery construction, chemistry, and/or operation, which when combined worst case will cause the batteries to overheat. This combination may only occur for a small number of manufactured batteries, and fires may occur only when those particular batteries are exposed to a worst case combination of stresses (temperature, charge currents, etc.).

Therefore a handful of test flights, of a few dozen hours or so total, are not nearly sufficient to empirically identify a low-probability event. The identification of such an event would require hundred or even thousands of test flights, which is obviously not practical. Therefore the only alternative is an investigation that drills down and positively identifies the true underlying failure mechanism (as recommended here: Flying the Flaming Skies: Should You Trust the Boeing Dreamliner?“). It is my opinion that this has not been done, because if it had, this knowledge would be trumpeted by Boeing.

I’m not flying the Boeing Dreamliner until I see the evidence that supports the optimistic conclusions of Boeing, the FAA, and the Department of Transportation.

-Ed Walker

Posted on April 19, 2013, in Batteries, Failure Analysis, Risk Assessment, Sample Size, Testing, Worst Case Analysis and tagged , , , , , . Bookmark the permalink. 3 Comments.

  1. At least they did not say, “read my lips”

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  2. There are 8 cells in the battery. They have prevented a fire in one cell from propagating to the others and causing the entire battery to burn as the one famously photographed battery did. Thus an entire battery won’t burn, the smoke will be vented, and an airplane won’t fall out of the sky. Therefore I would fly on a Dreamliner.

    The cause of the cell burning was charging at temperatures below 0 Celsius which irreversibly deposits metallic lithium on the anode. When this “moss” gets big enough, it pushes through the separator and a short results with pyrotechnic results.

    I have not heard if Boeing added a heater to keep from charging below 0 Celsius or not. If not, they will have additional cells fire off. But there are two batteries and the individual cells can be replaced. Again I will fly on the Dreamliner.

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    • Dear Mr. Haibel:

      Thank you for your comments. From a quick look at your web site, you appear to be an experienced and capable engineer. However, your stated comments are lacking supporting data. That’s fine, but if you had presented your comments to a failure review committee, my experience indicates that you probably would have received many questions; e.g.:

      You said: “…They have prevented a fire in one cell from propagating to the others and causing the entire battery to burn…”

      Q: Who is “they”? How did “they” prevent a fire from propagating? What are the possible adverse consequences of this measure?; i.e. perhaps the measures will make it more likely for a single cell to ignite. How did the fire start in the first place? Has this been replicated under controlled conditions? How do you know whether containment to a single cell is sufficient?; i.e. perhaps a single battery cell could rupture and jet out a stream of fire, like a welder, that could possibly melt a hole through the containment casing.

      You said: “The cause of the cell burning was charging at temperatures below 0 Celsius which irreversibly deposits metallic lithium on the anode.”

      Q: How do you know that? Has it been replicated? How would that explain the cases where fires have started in lithium batteries when the batteries are not being charged or discharged?

      Respectfully, until a comprehensive safety review process occurs (I have outlined the requirements for such a review in earlier comments), I will not be flying the Dreamliner.

      -Ed

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