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Fuel Tank Priming

asw20c

Well Known Member
I am in the early stages of building the wings. This past weekend I FINALLY finished fluting the ribs and have just started the final drilling of the upper and lower rib flanges. Although the plans were vague in this regard, when they said to flute all the ribs, I fluted ALL of the ribs to include the leading edge ribs. After final drilling, deburring, and dimpling, I will be priming them. I don't recall reading anything about this in the primer-war threads, so is it appropriate to prime the ribs that make up the fuel tanks? I am using the same Sherwin-Williams product that Van's uses, and my line of thinking is that perhaps exposure to fuel is not what Sherwin-Williams had in mind for their product. I'm wondering if there might end up being some sort of fuel contamination problem.
 
Vans directions

I read in Vans instruction for the 9 to not prime the fuel tank ribs. I did prime the skin, inner and outer ribs that will be exposed to air external to the tank. I did this because the tanks may promote condensation and I wanted these surfaces primed.
 
While you're at it...

You should probably prime inside the engine cylinders too, just in case.
 
You should probably prime inside the engine cylinders too, just in case.

Yeah, that's a pretty snarky thing to say on this forum. I'm in section 12 of the plans so I don't have the benefit yet of any instructions regarding this question. Most folks here have been helpful when questions are posed by new builders since not everything is obvious.
 
Ah just ignore him. He was probably joking anyway. Don't prime the inside of your tanks. People used to use some sort of sloshing compound to seal tanks. You put it in the tank and rolled the tank around to make sure it got everywhere. Then a few years later it would start peeling off the tank in chunks and clogging filters. There is a service bulletin about that. As a result, most people would cringe at the idea of any sort of coating on the inside of the tank. Do a search on sloshing compound or similar and you will hear horror stories.

I would not recommend priming your cylinders either:D
 
Ha! Got me!

Actually on my current airplane I use the throttle to pump fuel in as I crank. I have no primer. Works great.
 
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