AeroElectric-List Digest Archive

Sun 12/07/14


Total Messages Posted: 1



Today's Message Index:
----------------------
 
     1. 07:42 AM - Re: Dreamliner lithium fire final report (Robert L. Nuckolls, III)
 
 
 


Message 1


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    Time: 07:42:39 AM PST US
    From: "Robert L. Nuckolls, III" <nuckolls.bob@aeroelectric.com>
    Subject: Dreamliner lithium fire final report
    At 00:26 2014-12-05, you wrote: > >Very interesting read. Sound like a thorough investigation. One thing I >noticed that there was no discussion (that I could find) of changing to a >more traditional battery type or another version of Lithium such as LiFePo. Not the NTSBs job. Incident investigations are limited to deduction of root cause and chain of events that followed. The FAA will (and in some respects already has) responded with enhanced (read more educated) certification criteria. True Blue has been marching to the new drum and has been holy watered. I'm hoping to visit with the guys in Wichita that manufacture and market the True Blue line in the near future. I don't think the FAA has mumbled anything about banning one chemistry in favor of another . . . again, not part of their charter. But they have said that if you choose to incorporate a new product or process into your design, you need to demonstrate either (1) exceedingly improbable or (2) total mitigation for worst case events. There are a number of youtube videos but one in particular where the producer-director subjects the LiFePo cells to spectacular abuse yet fails to produce more than a few sparks or a little smoke. Clearly, the LiFePo chemistry is the most attractive product for future consideration in OBAM aircraft. Given that a series string of 4 cells cannot be abused by over-charging in a 14v system, it seems that the most challenging issues will focus on cost of ownership. If a cell is severely discharged (much below 2.8v) it's trashed. An array of cells subject to repeated deep discharge/recharge events is at risk for charge imbalance in one or more cells which places them at risk for early failure. We're fortunate to have access to a HUGE testing laboratory for rapidly growing numbers of LiFePo products . . . motorcycles and recreational vehicles. A market that is probably 100x larger than aviation applications. I do periodic web searches on motorcycle+lithium+fire and to date, I've not discovered any instances of mishap unique to or exacerbated by the application of lithium. If anyone runs across an incident of interest on the web, I'd like to get a note on it. Here is one interesting battery narrative from the motorcycle world http://tinyurl.com/3uccevs These guys are wrestling with the same performance and system integration issues we face. We would do well to study their experience for expanded lessons- learned. Bob . . .




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