Posted for REHBINC@aol.com:
In a message dated 2/24/2007 9:21:38 AM Eastern Standard Time,
glcasey@adelphia.net writes:
"""
There were several excellent comments on this subject. I was also
worried about this potential problem and here is what I did about it:
1. The filler necks were in the wings when I got them, so there was
no way to bring any ground to them. I connected a small chain to the
fuel level sensor outer tube, which is electrically connected to the
"ground" of the plane, and fished it out the filler neck. I
connected this chain to the filler cap. The chain is deliberately
made long enough to lay on the bottom of the tank when the cap is in
place. The idea is that the fuel hose, when touched to the filler
ring or cap, will ensure a discharge of energy. When the fuel is
pumped into the tank it swirls around the chain, preventing a charge
buildup within the fuel itself.
"""
First, gasoline is nonconductive so your chain will only discharge the fuel
that actually makes contact with it. But, every little bit helps. Second, the
big advantage I see here is that the chain electrically ties the filler neck
back to the ground system and, presumably, the exhaust, where you are
attaching
ground clamp. Third, a potential hazard of this system exists if the
electrical connection of the chain to the ground system is interrupted. Now
the induced
charge on the chain from the fuel is only connected to the filler neck. As
long as the chain, filler neck and nozzle are all electrically connected
there
should be no problem. But what if one of the three become separated from the
others by say 0.030 inches while refueling?
"""
2. I grounded the fuel vent line, which (I think unfortunately) is
conductive. Without this being grounded there exists in the tank a
"perfect" lightning rod with two long conductive elements pointed at
each other with an air gap between.
"""
Under normal conditions, the atmosphere inside a gasoline fuel tank is
nonflammable. However, this fix "may" help to save some of your
instrumentation in
the event of a strike.
Rob
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