Hi n3pup,

I would recommend protecting a wood structure that is near a gas tank with some sort of inert coating, gas on wood is a bad combo, brushed on laminating epoxy would likely be the easiest. A small kit of West System from a local boating store may be the quickest approach. Make sure to ratio it out exactly as they call for.

As for the aluminum tank I would look into self etching primers in a spray form where it will be a mating surface (assuming your going to have a polished alu outside tank?) a simple sanding with fine grid sandpaper or steel wool should work for prep, vacuum with a brush attachment the surface. I use Dupli-Color SE primer here is a link where you can get it at spruce

http://www.aircraftspruce.com/catalo...hingprimer.php

but the auto stores have it in stock, even some walmarts at a lower cost. This prep & spray combo has produced good results for me in a high humidity climate (So Florida).

As for the silicone I would look into aircraft or automotive grade 1 part RTV silicone in a tube, spruce has that to.

http://www.aircraftspruce.com/catalog/appages/rtv.php

You may want to check in with some of the auto stores and see if they carry it,

In practice both building Piston Aircraft engines (on my own time) or my full time job working on all the Fancy P&W commercial & military aviation gas turbines, aircraft / automotive grade silicone RTV’s are usually applied to metal components with out issue in a production environment. The bigger item to look out for is corrosion from moisture on the internal aluminum structure particularly with 2024, when I used to work for Piper they would paint or coat all the interior sheet metal components & skins before assembly. The only area I would watch out for is the inside of the tank, I would follow the manufactures guidelines on that, the wrong coatings can dissolve in gas & end up in your fuel filter.

Hope this helps

Spencer

EAA Technical Counselor # 5426