Trim Tab—squeezed the rivets on the bottom skin to the spar using a longeron yoke-not much room for the yoke behind the spar. Had to drill out two rivets and squeeze new ones. Then riveted the trim tab horns to the skin & spar, followed by the inboard riblet. Squeezed rivets on the top skin to the spar and hinge. Used pop rivets to finish installing the outboard riblet. Everything turned out well. Glad to be done with the trim tab—for such a small piece, sure seemed like it took lots on time to complete.