Still working on the aft ribs today. I started by fitting the BL 54.5 rib, but figured out pretty early on that it's aft edge, as it intersects the flap contour area, was at least 1/4 inch too small. That's too much, in my opinion, to take up with a micro release. So I cut out another rib and fitted it, to within less than 1/8 inch at all intersections. What takes so long in this process is placing and replacing the cradles, raising the lower skin, repositioning the skin, over and over again.