Fuel Cell Repair
Sent in Febr. 2005 by Ken Strite

I bought my plane with no fuel drains in the wings and wanted to install some. Thanks to Holger for selling me the ones he had. When I drilled the hole in the wing for the first drain I noticed the sloshing compound had peeled loose and was floating around inside the tank. I removed the wings and cut each bay open, and since the fuel quantity was only 44 gal total I decided to add 2 bays to each side.

See also: Ardis Almond's fuel cell repair article.

  Click on image for a larger view.
You can see how bad the sloshing compound peeled, here a slab of it is fouling the fuel quantity float arm. I found out when I opened the wings that the fuel pickups in the left wing (which is the one with the problems) did not have strainers on them and there was nothing keeping the sloshing compound from totally blocking the fuel pickups.  
Wings marked with panel numbers and cut lines prior to opening.  
Here's the sheet I drilled through originally. It measured roughly 8" x 10"  
You might be able to see the aft fuel pickup in the corner. It would have been very easy for blockage to occur.  
I started cleaning out the sloshing compound with MEK but found that acetone worked just as well. Neither did any noticable damage to the fiberglass or resin. I used various brushes and scrapers with the solvent but found that a scotchbrite pad worked best overall. I decided to keep the access hole to the flap mount bracket so I added a fiberglass bulkhead in the 4th open bay.  
After I had the wings as clean as I could get them I recoated them with ProSeal. I thinned the ProSeal in most places but where I knew I had leaks previously and on the fiberglass bulkheads I installed I put it on unthinned. I ProSealed aluminum strips in place to lay the skins back on.  
Fabricated new fuel pickups with strainers and also ran a tube from the fuel vent to the fuel cap area. In the past the fuel vent was so low I had to leave about 2 inches of room in the tank or fuel would dump out the vent all over the ramp. Now I can go to within a half inch of the cap.  
Prosealed the wing skins on and layed 2 layers of glass cloth into the Proseal. Then just for good measure I put a coat of resin on top of the fiberglass cloth. I think I could have skipped the resin. I smoothed it all out with microbaloons and repainted the wings. I did have one annoying leak in the right wing that had been there since I bought the plane. I ended up having to inject Proseal into the inner rib at the spar to get that stopped. I thought I had fixed it during the pressure test but it came back. It seems fixed now though. Total fuel quantity went from 44 to 68 gals and with all the Proseal I added about 6 pounds to the wings.  
A view of the finished wings at Sun-N-Fun 2004 just a day after finishing the job. If you look closely at the BD on the left you can get an idea of what it would look like without the finish work. Those are Norm Tanner's (Hugo's old plane) and Scott DeGaynor's planes next to mine.