Riveting stiffeners to the fuel tank skin.^6h

The day has come to mix some sealant and start assembling the right fuel tank!

The first thing was to clean the skin. I washed it first, then scuffed the mating areas, and cleaned them with naphtha until the towels would not pick up any dirt. Finally, just before the assembly, I wiped them with acetone.

I did not take a lot of photos, most of them I took only after I finished the work. It wasn't a particularly dirty process, but I had to wipe and clean everything all the time to keep the sealant in check.

I started by preparing some supplies. Some towels for wiping, paper strips to clean the rivet holes, popsicle sticks, and some Q-tips (I can soak them with acetone and do some targeted cleaning).

Also, I put some rivets in naphtha to clean them from whatever oil they might have on them. I scuffed the stiffeners and wiped them clean also.

After that, there were 4 hours of riveting all the stiffeners, the fuel flange, and the fuel drain flange. I pretty much followed the Van's RV Fuel Tank Construction Tips video.

This is what the end result looks like, the stiffeners.

The fuel flange, outside and inside view.

The drain flange.

After riveting everything together, I worked a little bit on fabricating an anti-rotation bracket for the return fuel line. The idea of the bracket is to lock the AN832-6D fitting so it cannot rotate when the return line is tightened or removed.

I started by doing some calculations based on the AN924-6D nut size.

This is what the prototype looks like.

The actual part is made from a 0.125"-thick plate of aluminum.

Somehow I managed to miscalculate the part a few times, but in the end, I got two brackets. One of them is a bit on the loose side, but it still would not allow union fitting to rotate, so it should be fine.

After drilling the holes, I realized that these holes were too close to the AN 6D spacer, so I could not put universal AN470AD4 rivets. After giving it some thought, I solved that problem by dimpling the rib, countersinking the brackets, and using AN426AD4 rivets with flush heads on the outside.