Commitment

Today's progress is proof that I am not afraid of commitment ! The day started by drilling the hole for the aft fuel tank drain required by AD. With the inside boot cowl access, I decided to put the drain outlet at the lower aft right side, this will allow you to stand in front of the tire, reach in and activate the drain and be able to catch the fuel in a suitable container. I cut a 5/8 hole for a 3/8 ID grommet and will use 3/8 vinyl tubing.
  After completing this item I removed the boot cowl, measured and drilled the aft mounting holes into the fuselage structure. I plan to use #6 screws so a #40 drill was just right. All the existing holes were stripped out and I did not want a miss match of giant screws.  I ended up with 6 screws with 4 inch spacing. With that complete , I reinstalled the boot cowling, engine mount, windshield mounting strip, and the instrument panel.

I then made a strap duplicator to allow me to accurately locate the holes in the fuselage structure. It is basically two pieces of scrap aluminum riveted together. These pictures should explain how it works.

I had to joggle the top piece because of the bead rolled into the edge of the boot cowling. The hole at the right end is drilled through and a locating pin (a AN 426 rivet) is installed with JB weld and tape.

 

In this picture you can see how it works. The locating pin is inserted into the hole previously drilled in the fuselage structure, the cowl is then pressed into proper position and the outside hole is perfectly located by drilling through the pilot hole. Here is the right side all drilled.

  Since I have conquered my fear of commitment I went ahead and drilled the left side too.

The only thing I did not like was how close the lower screw holes are to the stiffening bead on the edge of the cowl. This shot shows it. There was just no way to get the edge farther aft.

This completes the installation and repairs to the boot cowling ! Tomorrow I will remove this , enlarge the screw holes in the aluminum and begin to prep for paint. The weather man is promising a warm afternoon so I should be able to get the primer on tomorrow.  I will soda blast the rust stain off tomorrow because I think I'm going to leave the firewall with just the galvanize finish. I just don't think a white firewall will look right.

Here are a couple shots of it cleaned up a little.

 That's it for tonight.