Brief Description: Center Fuselage - Outboard Seat Ribs
I spent a good part of the day flying the 170 down to Agua Dulce and back for their Taildragger Fly-In. My sister-in-law rode down with me, and my 85-year old mother-in-law rode back with me, and had a blast! My good sport of a wife drove down providing ground transportation.
Not a whole lot of time on the build, but I did get both undrilled F-715 seat ribs fit to the center fuselage structure. Due to the bottom of the center fuselage being curved to follow the bottom camber of the wing, the flanges on the F-715 seat ribs cause a concave contour of the web, but a convex contour is required to follow the fuselage side. This is dealt with by fluting the F-715 flanges. As a reference for the proper curvature, I marked a line 5/16 inch inboard of each of the bottom flange rib holes on the center fuselage bottom skin (photo 1). I then marked the rivet positions on the bottom flanges through the skin holes, then fluted the rib to follow the lines on the bottom skin. I clecoed the seat pans in place temporarily and used their outboard edges as a reference for fluting the top flanges of the outboard seat rib. I marked centerlines on the top and bottom flanges of the outboard seat ribs to follow later when drilling the ribs.
The forward end of the F-715 ribs to not have a bent flange, just a flat one that fits inside the main spar bulkhead upright. After fluting the seat ribs to follow the fuselage contour, the front edges of the forward flanges interfered with the radius in the upright to which they attach. I had to trim the forward edges of these flanges on an angle from 1/16 inch at the top to 1/8 inch at the bottom for a proper fit.
I think I'm now about ready to turn the center section assembly upside down on sawhorses to finish clecoing and drilling the bottom skin to the ribs.
Marked a reference for fluting the outboard seat ribs.
The forward edge of the outboard seat ribs required trimming.