I rough cut all the left fuel tank stiffeners. 
After finishing the stiffeners, I clecoed them to the tank.
I masked the countersunk holes in the spar and primed the exposed aluminum.
I back riveted 3 nutplates to the underside of the spar. To set the rivets. I laid my tungsten bucking bar on the manufactured head and then I back riveted the shop head. It was pretty challenging to hold both sides. In hindsight, I probably should have used blind rivets to secure the nut plates.
