After some thought, I decided to install nutplates and use screws to attach the seat pans rather than screws in the forward portion only. I probably could have increased the spacing of the screws over the rivets, but I had already drilled everything so ohh well...
I fitted the seat pans back in place and drilled out half of the holes for #8 screws. I then removed the seat pans, installed nutplates in that first set of holes. After that the seat pans went back into place with screws and the rest of the holes were drilled out. I install all but a few of the remaining nutplates.
Gina bought be a #8 nutplale drill guide for my birthday which saved me a ton of time.
It took a lot of nutplates for just the seat pan area. In addition to the nutplates called out in the plans I added: 7 per seat rib X 8 ribs + 16 additional at F-605 = 72 additional nutplates. I will probably use nutplates for the baggage area also. However, I am considering using nutplates for just half of the baggage floor and rivets for the other half.
