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Repairing A fuel tank


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Hello Kevin Walsh

I have a slow tank leak that is emerging from the bottom corner where

the spar and strak meet.

I came across Kevins Walsh fix that he posted in response to S. Cambells

posting of "fuel tank" (topic message# 108414). Unfortunately, I had several questions.

Also, I was looking for some guidance here.

First question, would you (Kevin W.) change or handle the leak any differently from what you did

to fix your plane, Cozy IV (having had a year to further think on it).

Question 2: when you fixed your 10" square hole, could you tell me how you did it.

Did you re-install the foam? how did you glass the inside of the patch to seal it?


Question 3: Is it possible to instead of making a 10" square incision. Just Widen the 

gas cap enough that you could stick your hand in the tank to do the repair and be able to see

inside it. Are there bigger fuel caps?


Re: Fuel Tank

 Kevin R. Walsh
8/24/20   #108414  
On Mon, Aug 24, 2020 at 8:21 AM Steve Campbell via groups.io <campb001=umn.edu@groups.io> wrote:
I am finishing up phase one testing and I find that I get a dripping leak from one of the tanks if I fill it more than 3/4 full. Aircraft Spruce sells this stuff https://www.aircraftspruce.com/catalog/appages/gastanksealer.php  
to solve this kind of problem. Of course, I am extremely leery of putting anything in the tank that could delaminate and clog the fuel system. Anyone have any experience with it in a Cozy/Long/Vari? One of the questions on Spruce's web site was:
I had a problem on my right tank where when the tank was completely full, in a climb, it would wick from the strake to fuselage seam at the top, through the foam to a 1/8" diameter channel that I had put through to run the coax for my fuel level sensor, then into the rear cockpit as a drip-drip-drip.
I would suggest that there is no magical cure here.  You need to find the leak and properly patch it with EZ87 or whatever epoxy you used for your tanks.  In my case I ended up cutting a ~10" square hole in the strake top to access the corner, which had been insufficiently smeared with wet flox when originally.  I sanded down that intersection and put a nice EZ87 and flox fillet in there, and it has been perfect since then.


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