The V-shaped spar attaches to top and bottom edges of the AST skin. Shots 1 and 2 are attaching this to the top surface of the skin. Every other hole is riveted in the pics.
After completing the top surface I riveted the bottom skin surface to the four ribs. This all but closes the structure. Tim had viewed it yesterday and let me keep going. Note this is really P08-04 Step 1.
Last step is to rivet the hinge to the bottom of the spar and the bottom surface of the skin. At this point I noticed some shiny skin. Bother. I will have to prime this before I get to the last step.