http://electronicdesign.com/blog/dreamliners-shouldn-t-smoke
http://electronicdesign.com/blog/dreamliners-shouldn-t-smoke
Dreamliners Shouldn’t Smoke
Jan. 8, 2013 by Don Tuite in Secondary Emissions
It’s Tuesday, January 8, and the newspapers are reporting an electrical fire in an empty JAL 787 Dreamliner at Logan.
Cleaning crews reported smoke in the main cabin
and the cause seems to have been an overheated backup battery
for use when ships power is unavailable.
I’d like to think that would have had a fusible link as a last line of defense.
But it’s hard to track down what the FAA might have said about that.
As a former aircraft owner (Taylorcraft, Stinson, 172, Challenger, PA26-235),
I’m aware of Advisory circular 43-13-2B:
Acceptable Techniques, Methods and Practices, Aircraft alterations, so I took a look in there.
No joy. Fuses and breakers go where the Certificate of Airworthiness says they should go.
But no doubt there’s a tome somewhere that has something to say about it.
In any event, the incident reminded me of a conversation I had with an old time engineer when I was fresh out of school and working at Garrett AiResearch in the mid-1960s.
(He was lead on some electromechanical control-actuation systems for the C5-A
and I was “managing” the contractual engineering data, which primarily meant qualification testing.
Essentially, he warned me never to fly in a new aircraft type until it had several years of commercial service logged.
Case in point was the 747, which, as far as I know, was the first to have a common bus for controlling entertainment, overhead lighting, and such passenger amenities.
Sure enough, reports started coming in about seat-arm controls turning on lights across the aisle and things like that.
Nothing affecting safety of flight, but the sort of thing to make a thinking passenger nervous.
The big deal about the Dreamliner is its use of composites, which seems to be an issue with some people.
Never mind that the use of composites goes back to the F-111,
which I also did some paper-shuffling on at Garrett.
(Aileron jackscrews, as it happens; I was trapped with a bunch of mechanical engineers for a while there.)
The boron-epoxy bits held up quite well there, and we’ve been using them for 43 years now.
By the way, there’s an interesting book (published 2001) that you can download here:
(It’s a search result; I Googled C-17 and composite.)
Which brings us no closer to an explanation of the smoking battery at Logan.
Next week we’ll know more.
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