Installing the nutplates for the cover plates of the new inspection holes. The sequence is important....install the nutplates for the cover first...then screw the cover to the doubler, and then when you fit the insert cover in place, you can through drill the rivet holes for the doubler to the wing skin. Result = exact positioning. If you do it reversed like the manual calls out (through drill doubler to the wing skin first, then the cover nutplates), it's a SWAG/guess to position the cover.