Moved Rt wing to cradle. Deburred inside of spar.. Clecoed L. Flap skin to PVC pipe. Rolled top skin 270 (needed 3 people to hold proper pressure on table). Marked bottom rib flange centerline. Clecoed ribs to top skin. (Left first 3 rows of clecoes out to make it easier to insert spar). Inserted spar. Finished clecos. Turned flap over and checked for twist.