On Friday night I drilled out all the trim tab rivets and inspected the parts to determine what had caused the skin buckle. It was good practice removing rivets, and It was mostly straight forward. The thin skin is so easy to bend, you need to be super careful not to damage it when popping off the heads of rivets. In this case the skin was already damaged so I just moved quickly. I decided to order a new spar too, since drilling out all of those rivets will inevitably enlarge all the holes, even if just slightly, which makes for a weaker part.
I confirmed the problem, and found that the horn was not completely square. You can see it in this picture where the silver clecos are making a v shape, rather than being parallel.
I bent the pieces to 90 degrees, and now they look much better.
On Saturday I prepared the elevator skins by measuring out the location of the foam ribs, marking them on the skins and read spars, then masking the area. A quick scuff of the areas where glue will be applied, then cleaning with acetone, and finally peeling off the masking tape. The spars were already primed, so I taped them, wiped off the primer with acetone, then scuffed and cleaned each area too.
Tonight I started assembling the elevators by riveting a gusset to a rib, then riveting the tip ribs together on each end. The only challenge was getting at the gusset rivets, where a rib flange was blocking on one side. I ended up bucking them with a double offset rivet set, which was fine, except when the gun jumped off the rivet for a moment and left a smiley face in the rivet. Looks ugly, but structurally ok.
I used a clamp and a board to keep pressure on the tip ribs while I riveted them. This was to help ensure the part came out straight.
