I wanted to protect the instrument panel from drill shavings as best I could so I draped this blanket in the fuselage to catch the shavings.

I intentionally made the flange on the instrument panel and the flange on the firewall slightly wider than they needed to be to allow this piece to be screwed into place using nutplates. The builder of this airframe didn't fasten this piece of skin to the firewall at all. He just fastened it along the fuselage stringer and at the instrument panel.

I started with a single hole centered [hopefully] on the firewall flange, the instrument panel flange, and, of course, the piece of metal itself.

From the single hole at the center, it was just a matter of drilling and clecoing one hole at a time down the sides.

I don't have pictures of the process, I guess, but I did my best to have uniform spacing of the holes even though the piece is curved. To do this, I used a fan hole spacing tool and put evenly spaced holes on masking tape. I then stuck the masking tape to the curved piece of metal and marked the holes locations in the metal.

Since I'm re-using existing nutplates previously installed along the fuselage stringer, I had originally planned to use a strap duplicator to locate the holes in the new piece of metal. It was pretty obvious right away that this wasn't going to work so well.

I fell back to my trusty blue masking tape. I carefully put the masking tape along the edge where the new piece of metal would meet the existing fuselage skin along the stringer. I marked the beginning and end of the tape and then poked holes wherever there were nutplates.

I then transferred the marked up piece of masking tape to my new skin and started drilling holes. I'm happy to say that it worked out very well.

I found that my canopy skirt no longer fit very well where this new forward skin butts up against the skirt. My best guess is that when I changed the original canopy hinge configuration, I managed to slightly alter where the radius of the canopy actually meets with the instrument panel.

Whatever the cause, I had to add a few shims under my new forward skin piece to properly align the canopy skirt. I could have made the shims removable, but I figured that would be a pain in the tookus down the road.

What I ended up doing is double-flush riveting the shims in place. Double flush riving is when both ends of a driven rivet are flush to the surface. You countersink the skin both on the manufactured (tapered) side of the rivet and on the shop head side (that's the side you squeeze or hammer flat with a rivet gun.

 

OK. Back to pictures of the construction of the actual tank itself. I fabricated and installed this vent line. We figured that the front of the tank (towards the firewall) would be the highest point of the tank in almost all conditions so that's where I routed the vent line.

You'll see in later pictures that this vent line was glued in place before we sealed the tank.