2.5 Hours -
Its finally time to test my first fuel tank for leaks. I have one of the fuel tank test kits form Van’s, which consists of a cap for the fuel pickup line and a inflation stem that screws into the tank drain flange. After the pickup line and drain are plugged, a balloon is placed over the vent line fitting to act as pressure relief for the tank and give a visual indicator of air pressure.
Once everything was ready, I sprayed the tank down with some soapy water and then started pumping air into the tank. All of the rib and stiffener rivets checked out fine, as did the fuel cap and drain. However, I found four small leaks on the baffle to skin joint. After cleaning up the tank, I made my first attempt to fix these leaks by smearing some sealant on the outside of the joint. I’m hoping this is all it takes since the next step may be to cut access holes in the baffle. Because all of the leaks are in the baffle/skin joint, I’m also going to change the way I seal the baffle when I get to this stage on the left tank.
The right tank had four leaks in it...all in the baffle to skin joint.
To fix the leaks, I tried spreading some sealant over the baffle/skin joint. Since the leaks are small, I'm hoping this will be all that is needed.
After testing and, hopefully, fixing the right tank, I started to work on the left tank again. I thoroughly cleaned the tank, stiffeners, fuel cap flange, fuel drain flange, and a bunch of rivets with MEK. Then, I taped all of the stiffener rivets into place, mixed up some more sealant, and back-riveted the stiffeners to the skin. After each stiffener was riveted, I made sure it had a solid filet of sealant around the edges and then encapsulated the shop heads in sealant.
I cleaned the left tank skin and stiffeners with MEK before riveting.
The left tank stiffeners have been back-riveted to the skin.
Once the stiffeners were done, I went ahead and riveted the fuel cap flange in place. This flange can also be back-riveted, and I even remembered to place the vent line clip on the correct side of the flange this time!
The inside of the fuel cap flange...riveted and sealed. This time, I place the vent line clip on the correct side!
The top of the left fuel cap flange.
Finally, I used my squeezer to set the rivets for the drain flange and then cleaned up the outside of the tank.
I made sure to leave paths for water to reach the drain when I encapsulated the drain flange rivets.
