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Fuel leak

Megs4sale

Well Known Member
Looking at purchasing an RV7 that has a few upper inboard rivets leaking when topped off. See photo. Appreciate insight on repair difficulty. Excellent paint job hate to risk tank removal but need to repair in some fashion. Thx
 
No picture showing.

Only advise I can offer, the sooner you repair it (by any method), the less the leak will propagate to the adjacent areas, making it a bigger job. Factor it into your purchase price!
 
My RV4 has developed a seepage of fuel from the drain flange to bottom of tank join. It was hard to find as the blue stain was on top of the wing, It had migrated in between wing and fuse then out under the fairing.
Does anyone have any ideas on fixing this without having to remove the tank or the access plate.
If the drain flange has to be removed for re sealing could it be done with pulled rivets?
The whole problem comes from using mogas, which affected the proseal. It first caused bubbling of the paint under some of the driven rivet heads.
 
When you say 'drain flange', do you mean the quick drain on the bottom of the tank? If so, the stain should have been obvious around the flange of the drain. Leaking fuel will definitely migrate around during flight, but if you didn't see it around the drain flange, it's probably leaking elsewhere.

While you might be able to drill the rivets off the flange & use pulled rivets to replace it, you'll be leaving the rivet tails inside the tank. *Probably* not that big a deal, but....

Having pulled the tanks on a -4 several times, I can tell you that it's not that big a deal. There are no bolts through the spar, like the 7, 8, etc. If you're proficient with an impact driver (screw gun), you can have the tank off the wing in a half hour. Drain the tank (gotta do that, regardless). Remove the root fairing, disconnect the vent line, supply line, and float sensor wire. Remove the nose backet attach bolt. Start removing screws. Leave at least one screw partly threaded near the center on top, as a 'safety', but it's unlikely to be needed. If the builder dimpled the tank skins where they attach to the spar, you can slip thin plastic strips, or even popsicle sticks under the flange to lift the dimples out of the spar as you remove the tank (helps avoid scratching the spar). You can put a padded stack of 'stuff' under the tank for insurance. Once you're ready to pull the tank, remove the last screw. It's usually easier to get the tank 'moving' by pulling forward on the root end first. Wiggle it forward & off the wing.

Trust me; you'll drive yourself crazy trying to do the repair on the wing, and you'll likely miss (or cause) another leak in the process.

Charlie
 
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I have had all night to think about it and it seems I will be better off removing the tank. I can then remove the plate for the fuel gauge, drill out the rivets in the drain flange, which is the fuel drain holder, then I can re rivet or even put 1/8" bolts instead of re riveting.
Just not looking forward to all the work.
Thanks for the advice.
 
The whole problem comes from using mogas, which affected the proseal. It first caused bubbling of the paint under some of the driven rivet heads.

A lot of RVs have used mogas for many years with no tank problems. Most
RV-15's use mogas (with ethanol) nearly all the time due to it being the recommended fuel for the Rotax engine.

I really doubt mogas was the root cause of your fuel leaks if the sealant recommended by Vans was used during assembly.
 
Heh heh...

I agree with Sam's assessment on the mogas, though. And I certainly wouldn't replace 3/32" rivets with 1/8" bolts.
 
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