Didn't have much time left but made a start on riveting the left flap. First I squeezed the AN470AD4-4 rivets joining the four internal ribs to the rear 'spar', which was surprisingly harder than I'd have expected. That 'lip' on the rear spar made it difficult to get the squeezer in there properly (I had the manufactured round head on the inside so I could pull against it with the squeezer and keep the tab 'closed' while I set the rivet). Then I assembled the whole flap together and dropped it into the now-ready assembly jig that I had just finished.
