Today I installed the window latch doubler in the left wing per section 49 of the manual1. This had to be done before the bottom row of rivets can be installed for the first leading edge skin and requires precise measurement in order to ensure that the doubler sits tightly up against the back flange of the skin. I started by marking the back edge of the skin on the ribs with the clamps on in order to get a starting point. I then removed the clamps and put the doubler roughly in position. I knew that it would need to be a little farther forward than the previous back flange of the skin since the extra thickness of the doubler and its rivets would cause the skin not to reach as far.
With the doubler carefully positioned in what I believed to be the correct spot, I compared this measurement to the first wing in order to make sure it came out close. After that, I ensured that the doubler was square (same distance from both sides to the spar) and centered before drilling the front two holes. These just go through the doubler and the rib so, with both drilled, I installed the rivets per section 491. Finally, I reinstalled the skin and got the back flange over the doubler. This was tricky because it was a closer fit than on the first wing I did. The fact that it was a close fit was intentional but it was even a little closer than I had intended. Because there was not much extra “slack” and the skin had to extend down farther off the rib until the flange was past the doubler, it didn’t want to go on. I ended up having to tighten the clamps most of the way (so that there was just a little gap between the doubler and the skin flange) and then push from the front like I was trying to push the slack out. This, combined with pulling from the back, just barely got the flange past the doubler so that I could tighten the clamps the rest of the way and build a little more of a gap between the two parts.
The next, and final, step to complete section 491 is installing the bottom row of rivets; however, I was tired and out of time so that will have to wait for next time.