FUEL TANK REPAIRS
Illustrated examples:
Look at a few examples and the problems that some discovered. The images do tell a lot.
Steps to follow for fixing them right:
BY SYD COHEN E.O.C. #4095
Many people are experiencing fuel tanks leaking or seeping, and the first thought is usually to slosh the tanks. If you use auto gas, do not slosh your tanks. There is no sloshing compound approved by the Feds or the compound suppliers for use with auto gas. Also, sloshing does not cure a corrosion problem.
The following procedure will work much better. This procedure should only be done under the supervision of an A & P mechanic.
1. Drill out all of the rivets with a #31 drill bit.
2. Use paint stripper to soften the old tank sealant and use a beveled putty knife to separate the metal sides from the top and bottom. Do not dig into the metal. Use the same method to separate the quick-drain fittings and all other fittings.
3. After the parts are separated, use more paint stripper to remove any remaining sealant. Paint stripper will also remove any old sloshing compound.
4. Order a sufficient supply of 5/32" dia. soft flush rivets, (AN 426A-5) 3/16" long and redrill the holes in the tanks for these rivets using a #21 drill bit. You must re-dimple the rivet holes for the 5/32" flush rivets. Cleco as you go.
5. Etch all inside surfaces with metal etch such as Stits Aluma-dyne etch or equivalent. Follow the directions carefully. Rub with a coarse (reddish-brown) Scotch-Brite pad dipped into the solution. Protect skin with latex gloves and eyes with eye protection.
6. If deep corrosion is found, the part will have to be scrapped. New parts can be obtained from Univair. (maybe not anymore - the editor)
7. Treat inside surfaces with aluminum conversion coating such as Stits Aluma-dyne Conversion Coating or equivalent. Follow the directions carefully.
8. Spread PRC or Pro-Seal sealant on both mating surfaces as you close them together. Spread with a Popsicle stick. Use 2 hour or slower PRC or Pro-Seal