Turn the cockpit fuel selector valve to the "OFF" position.
Open the leaking fuel tank's fuel sump drain. Drain all the fuel from the tank into clean buckets. Close the fuel sump drain when the tank is empty.
Remove all the screws from the fuel tank's perimeter with a Phillips screwdriver. Ensure you do not strip the screw heads.
Slide the tank slightly forward to gain access to the vent hose and fuel tank sender wire. Loosen the vent hose clamp with a Phillips screwdriver. Remove the hose. Remove the fuel sender wire with a 3/16-inch box wrench. Remove the fuel tank from the aircraft. Place the fuel tank on a clean work bench.
Inspect the fuel tank. Aviation gasoline is dyed blue, which aids in the leak detection process. Any fuel tank leaks show up as blue stains. The fuel tank is a riveted structure; therefore, look for leaks around individual rivets and seams. If any cracks or corrosion are found, they must be professionally repaired.
Clean the areas around the leak using a solvent such as methyl ethyl ketone, also known as "MEK." Use rubber gloves to protect your hands.
Mix enough aircraft fuel tank sealant to cover the areas you previously cleaned. Apply a liberal amount of sealant with a small putty knife. Allow the sealant to cure for the time recommended by the instructions.
Check the fuel tank for leaks. Fill the tank with fuel while the tank is still on the work bench. Allow the tank to sit overnight. Observe the tank, work bench and floor for signs of leakage. Drain fuel from the tank using the fuel sump drain.
Reinstall the fuel tank into the aircraft. Reconnect the fuel vent hose, and tighten the hose clamp. Reinstall the fuel tank sender wire. Insert and partially tighten all fuel tank screws. Finish tightening the screws after all screws are installed. Ensure that the longest screws are installed into the spar.
Pour the fuel back into the repaired tank. Turn the fuel selector valve to the "ON" position.
