With the Horizontal Stablizer spar assembled to its doubler and two spar caps with clecos, I could now begin riveting them together. This involved both universal head and flush head rivets of multiple lengths, so it was important to keep track of which ones went in which hole. Fortunately I was able to squeeze all of them with my hand riveter. I did notice that some of the rivets in one of my jars were mixed up with rivets that were slightly too short, so I had to spend a little time hand-sorting them into the correct jars.

What's next? Time to start preparing the ribs to be assembled together.