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Fuel tank sealant

Old 08-12-2002, 08:45 AM
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Default Fuel tank sealant

What is the best way to seal the fuel tank where it passes throught the firewall?
Old 08-12-2002, 09:04 AM
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Default Fuel tank sealant

Because it is so hard to seal up that appx 1 inch dia hole... I avoid having the front of the tank poke through the firewall. Smaller holes mean less fuel seeping.

For the pre-cut holes in some ARF's and kits, I'll laminate a layer of 1/32 ply over the face of the firewall with epoxy, and drill it for the fuel tubes after epoxy coating the face. this leaves virtually no room for fuel seepage. And the thin ply, coated with epoxy both sides, is virtually fuelproof from even the drilled hole edges.

You can coat the cut hole with epoxy and use the foam rubber that comes with the kit for sealing.. and it will still get fuel inside the fuselage. the only things that have helped prevent/reduce the damage for me have been painting the fuel tank compartment inside, and packing arond the tank with an absorbant material (tissues..) which is replaced after each day of flying.

A drilled hole, coated with epoxy inside the bore, which is a tight fit around the fuel tube works fairly well... A bit of a pain to force the fuel tube through though.

Anther option is to epoxy a short piece of brass tube in the firewall and connect shorter pieces of fuel line, inside and outside. (very hard if there's no hatch for interior access) This needs reular inpection inside to be sure the connections are tight anf the tubing s in good shape.
Old 08-12-2002, 09:20 AM
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Default Fuel tank sealant

Fuel tank is not supposed to pass through the fire wall. I presume you ment to ask about the "fuel tank neck".

If you make a hole large enough to have the neck/cap pass through a thin (1/4 in) fire wall, then silicone sealent can be used. Let it cure over night, you can cut the sealent with an X'acto for repair etc.

Alteratively make a hole in the fire wall about the same dia as the tank cap, fix a circular rubber seal in this hole using CA (either 3 mm thick rubberfoam sheet or rubber from bicycle tire tube). The Dia of the hole and rubber seal is the same, so that the seal lies flush with the front of the fire wall, and is held inthe hole itself. Next make 2 or 3 holes in the rubber seal with an awl so that the fuel lines can be drawn through these.
Old 08-12-2002, 10:31 AM
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Default Fuel tank sealant

Yes, it is just the neck of the tank. It's an ARF (Hobbico Avistar) with the pre-cut 1 inch diameter hole. FH's idea with the laminated ply sounds like it would be the most effective (and probably easiest.

Thanks, Randy

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