I used a nutplate to drill out the nutplate rivet holes on the longeron (for the mid cabin cover screws and then countersunk the rivets holes for flush screws. Drilling and countersinking was accomplished using the angle attachment on the drill. The holes are so close to the side skins that it's difficult to get in there.
As such, riveting the nutplates was not easy either. I tried both the squeezer and the gun and neither one could get into the alloted space and get completely perpendicular so the "flush" heads of the rivets are not entirely flush in all cases. I drilled two out that were pretty bad, and replaced them with some "pretty good" ones. They aren't structural, the just hold the nutplate until the screw is installed.
I then realized that the nutplates I had just installed were not tapped to allow the screws to easily enter... It was then that I remembered some advice my buddy Bob from Virginia gave me - a few months back... it was to pre-tap all of the nut plates in inventory so that you don't have to do it after the nut plate is installed. I knew it was a good idea, but I haven't gotten around to it...until today.
