To protect the fuel tank inside the wing, adhesive cork strips are run along the fuel tank welded edges as well as across the tank spanwise. The task is straightforward and easy to do. The important thing to remember is to build up the layers of cork so they stick out further than the welded flanges so the tank doesn't come into contact with the wing skeleton.
With the tank corked up, its final position inside the wing is set, so I turned to the task of cutting a circular hole in the leading edge skin to accommodate the fuel filler. I started by cutting a 60mm hole (the desired size) in a piece of clear acrylic using my trust flycutter. I then attached the acrylc to the fuel tank by screwing the threaded fuel cap assembly into the threaded bushing welded to the inside of the tank. With the acrylic template secured in position on the tank, I drilled three holes into the template that matched 3 corresponding rivet holes in the main spar. The result was a piece of "transparent aluminum" (like Star Trek!) that was clecoed to the spar like the leading skin wil be with a perfectly aligned fuel filler cap hole in it.
Next, I transferred the template to the leading edge skin by clecoing the acrylic template to the leading edge skin, being careful to use the same pre-drilled holes that lined up with the ones I used on the main spar. Once the template was in place,I simply used the cut out hole in the acrylic to draw a circle onto the leading edge skin. After that, I simply had to find the middle of the traced circle (what's YOUR favorite method?) and go at it with my trusty flycutter. It all seems good so far - we'll know more when I wrap the leading edge skin back down into position.
The cork along the inboard welds and across the span of the tank.
Clear acrylic template with a fuel filler hole in it attached to the main spar.
The finished hole in the leading edge skin with the fuel filler collar in place.
