>
> Thanks Fred, oh great Guru, :-))
> Your right, but I wanted everything I could get to drain off any
> charge.
>
> Jim Nelson
> N15JN
Your point is not invalid, as I just looked up (which gurus wouldn't
need to do!). FAA says that conductive things exposed to fuel inside
nonconductive tanks do shorten the time for self-discharge to naturally
occur. However, it's insufficient to prevent buildup during refueling.
Where fuel is being sent down a filler pipe, the preventative measure
is merely large pipe to reduce flow velocity.
However, lightning protection is important also, and one method to
obtain certification of composite aircraft is total electrical isolation
of the tank. The means no electrical fuel level senders, metal vent
lines which terminate in a conductive something extending from the
airframe, grounding wires, or even a metal fuel line which is grounded
or within arcing distance of electrical wiring or control systems. This
also can mean the filler opening too (which should be grounded of
course), where there is a run of filler pipe to the tank, but a
suggested solution is to interrupt conductive pipe with section(s) of
nonconductive hose. Since aircraft are refueled far more often than
exposed to lighting strikes, I guess what they're saying is that static
inside the tank is harmless in fueling operations. Mixture's just too
rich in normal ambient temps -- well discussed in gov't report on the
tank explosion on TWA 800.
Regards,
Fred F.
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