Although this question relates directly to the NTSB findings on TWA Flt800, I was always puzzled and dissatisfied with the reason that failure in the instrument wiring harness inside the center wing fuel tank(CWT) caused the unvented fumes(a failure in itself) to explode; given that instrument circuits use microamps at 28vdc, resulting in less than .02Joules at best to transmit signals. A probe heater of course would be different, but that wasn't given as the reason. Are there any other instances where wires 'shorted' in an instrumentation circuit could cause sufficient energy to create a spark?

This question is not about "what really did happen" to TWA800; this is about whether or not the NTSB(National Transportation Safety Board) made a correct analysis in implicating Instrumentation Wiring.


A joule (J) is a unit of measurement of electrical work or energy; 1 J is the amount of work done by 1 watt of power in 1 second. The power supplied to the FQIS components through the cockpit fuel gauge (0.02 mJ) is about 10 percent of the minimum ignition energy (MIE) requirement (0.25 mJ) for hydrocarbon fuels, referenced by the American Petroleum Institute Recommended Practice 2003 (API 2003), Protection Against Ignitions Arising out of Static, Lightning, and Stray Currents, fifth edition, December 1991 Taken from here

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    $\begingroup$ I feel this is more appropriate for physics.SE (spark gap as function of tension, energy released as function of gap, tension and current, etc.) $\endgroup$
    – Federico
    Oct 1 '14 at 14:45
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    $\begingroup$ I don't think there are only signal wiring in those harnesses. There could be power lines to instrument sensors and other circuits in the bundle. $\endgroup$
    – JerryKur
    Oct 1 '14 at 16:16
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    $\begingroup$ @user2479 After your edit, it has become opinion based. $\endgroup$
    – Farhan
    Oct 1 '14 at 20:24
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    $\begingroup$ the answer is that you have to compute the Joules, hence is a physics.SE question. $\endgroup$
    – Federico
    Oct 1 '14 at 21:29
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    $\begingroup$ I feel it would be better if you would ppass by chat. Anyway, as it stands now, you are asking whether or not the NTSB made a correct analysis in implicating Instrumentation Wiring, i.e. to redo the analysis, an analysis that involves lots of physics' considerations and computations. $\endgroup$
    – Federico
    Oct 2 '14 at 5:46

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