How to seal and secure an AN bulkhead fitting.

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GESchwarz

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I am installing the vent line into my integral aluminum wing fuel tank, using a standard AN bulkhead fitting.

What kind of fuel sealant should I use?

The nut that secures the fitting is inside the tank. How do I ensure that the nut will not loosen? Do I use a thread locking compound or does it need to be safety wired?
 

Toobuilder

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Mojave, Ca
Rivet a piece of aluminum to engage one of the flats on the nut.

Find a drawing of any RV fuel tank. They all have solved the problem you have.
 

GESchwarz

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Ventura County, California, USofA.
Roger Wilco Toolbuilder. Thank you.

I see that you are a neighbor of mine. I plan to do all flight test and hours at Mojave...Less things sticking out the the ground if I have to put it down somewhere.

The bulkhead fitting is a 90 degree elbow, so I will need to prevent that from rotating also.

Any idea about sealant? Is a good automotive fuel proof gasket-maker sealant good enough if I will be using auto fuel with my Mazda rotary engine?

Is there a publication that addresses these sort of ordinary assembly proceedures? My old A&P and standard FAA repair books do not provide any of this kind of information.
 

Toobuilder

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RV's use a 90 on the fuel pickup but the nut is on the outside. Anti rotation of the fitting is an "L" bracket riveted to the rib with the nipple end of the fitting poking through a hole in the "back" of the L.

Use Proseal or the equivalent aerospace tank sealant.
 

GESchwarz

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Got it. I was thinking the same thing about the angle with the hole.

So on the sealant, we never use a one-part compound on anything, even for auto fuel.

It's just that it's difficult and a pain to mix a 10/1 ratio Proseal for such a small batch. If you don't get the ratio right on a 10/1 it may never cure.
 

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