Worked on learning how the horizontal stabilizer is fit to the fuselage. Verified the existing fuselage longitudinal centerline on the aft deck at the F-710 and F-711 bulkheads. I located the four bolt holes that attach the HS to F-710, and marked them on the aft deck (photo 1). The dimensions called out on DWG 27A look like they’ll work pretty well to put the outboard ones in the center of the 5/8” wide horizontal leg of the longeron, but I’ll do a little more measuring to make absolutely sure. On the HS-714 attach angle, the fore and aft location has a little leeway. The lateral edge distance might be a little close, but I think it will work out. If not, I’ll fabricate another one when I do the doubler service bulletin.
Since there no wiggle room in the location of these holes due to edge distance on the longeron, I plan to first drill these holes in the aft deck from the top using short threaded-shank bits in my 3/8” stroke countersink cage to keep the holes square to the structure. I will then clamp the HS in place along with the F-798 shims and back drill from the bottom. With a jobber-length bit in my 90-degree drill I’m pretty sure I can finish the hole before the .7” head gets to angle legs. We’ll see.
I spent a lot of this session trial fitting the horizontal stab (photo 2). There was a few thousandths of interference between the inboard edge of the stab skins and the longeron (photo 3), but a little work with the hand seamers took care of that.
The more I think about it, the more I think I will wait until after doing the HS doubler service bulletin to actually start drilling for mounting the stabilizer.