Clecoed and riveted upper inboard wing skin W-1201B-R (page 17-03, step 4). Screwed up and installed rivets into spar at aft end of where skin doubler is riveted. Had to drill out 20 rivets. Was able to retrieve all 20 shop heads inside wing and clean out shavings.
Clecoed upper outboard wing skin W-1203B-R. Tired so going to call it a day.
