This entry covers several days, mostly just deburring and whatnot. But, when I was working on the left F-770 skin, I discovered 3 blown out holes. 2 of them were actually figure 8s and one was oblong. Whats worse, they are the 3 aft holes common to the F-770, F-7101 Gear Attach Web, & the F-713 Aux Longeron. Simply put, there's a lot going on in that location. Since this area is hidden by the wing root fairing, I toyed with the idea of a -5 rivet, or external doubler or whatever, and even dimpled them to see how bad they were. Ultimately, I decided to just bite the bullet and order a replacement skin. Especially since this is the one that had a crack in the aft conical bend.
None of the sub structure was damaged, so I think what happened was that I match drilled this with the plastic on and the plastic had stretched so that the holes in the plastic weren't aligned with the pilot holes in the F-770. I really cant explain it, but you can clearly see in the picture below that the lower longeron right behind it doesn't have a mark on it. It's on the side of the airplane furthest away from the overhead lights, so maybe I was drilling with some weird shadows or something, but I really have no excuse.
The replacement came today, and I'm once again amazed with the precision of Vans match drilling. It clecoed right up with absolutely no drama, so I elected to remove it and just final size the holes on the bench, so as to not potentially oversize anything underneath.
Funny how you get faster the more times you do something. The Fedex Truck dropped it off at about 1030, and I had it deburred, edges smoothed, and the conical bend done in time to get some primer on it before dark, which is good because its too big to prime in my little temporary paint booth and today is supposed to be the last warm day for quite a while. I'll let the primer dry for a day or two then dimple and this should be done!
Before fedex showed up, I was killing some time in the garage and decided to do something I've seen other builders do, which is to beef up the armrests. As designed, they are pretty flimsy and can be easily bent by people shoving off of them to get out of the airplane. I pondered this for a while thinking about the best way to attack it, and ultimately came up with a neat solution.
Cut the J off of some left over J channel scraps so that it ended up as a simple piece of angle. Then match drilled as seen in they pictures below. This stiffens up the whole thing, as well as eliminates the sharp edge on the lower cabin side. I'm not going to rivet this until it's clecoed in the fuselage, since it's still pretty twisty just clecoed together and I don't want to unintentionally lock in a twist that will cause it to not fit right by riveting the stiffener on before it's clecoed to the skin and bulkheads.
Overall, a good few days and a ton of progress today. Even the conical bend came out really pretty.