I prepped up the doubler strip, drilling out the holes to a #7 deburring, and dimpling, and countersunk all the nutplate attach holes. Then riveted the nutplates and strip to the firewall as directed. I have a little confusion about the short pieces on the ends so I waited on those.
I was only able to make the 25 7/8 " hinge piece but I fit that on and then drilled the holes to that, leaving 1/6" of it above the flange of the firewall as directed.
