Backriveted stiffeners to elevator skin. Riveted 410 and 411 reinforcing plates and nutplates to spar. Centered control horn on spar and drilled horn to spar. Drilled spar to root rib and deburred holes. Drilled holes w/#41 bit. Dimpled all holes. Dimpled holes in spar opposite direction. Possibilities: Flatten dimples w/flus set drill w/#30, using -4 flush rivets.
