Aft Fuse Attach

Over the last couple of evenings I completed one more step in the Aft Fuselage Attach chapter. It’s slow going, but that has been a combination of tricky to access rivets, and a lack of time to work on the plane. I’ve been chipping away at it to keep some momentum going, which is the most important thing I think.

The step I completed was riveting the baggage compartment floor ribs to the bulkhead at the back of the baggage compartment. There are 4 ribs on each side, but the outermost are riveted later, as they need to be flexed out of the way to set the lap-joint rivets. For the 6 ribs that were riveted in this step, I used my gun with offset rivet set to get the 470 head rivets. It was a bit questionable, because I couldn’t get the gun completely square on a few rivets, but mostly the shop heads came out looking great. The bottom rivets on each rib are pop riveted, because it’s just too tight down there. I dusted off my pneumatic pop riveter, tested it, found my “wedge”, and then set them with surprising ease and good results.

Next step is riveting the ribs to the skin on the forward side of the fuse join, on sides and bottom skins, then it’s onto the lap joints, and finally the last baggage floor rib.

Tonight I set a few more rivets, including the first few rivets that actually joined the two halves of the fuselage. Up to this point the riveting has been aft fuse to bulkhead, tonight I worked forward and started riveting the two side skins together. I had to fiddle around a cut a couple of rivets to -5.5 size, since -5 seemed a bit too short. With all the layers being riveted, and all of them being primed, I’m going with slightly longer rivets to make sure they have a good shop head.

Tonight I did some back riveting using a couple of tables I made the other day. I decided to back rivet the side skins, and probably as many rivets as I can, on the fuselage join. The main reason for back riveting these rivets is that access is very hard (not impossible) for bucking them by myself. The second reason is that back-riveting results is a nice flush finish where the skins come together. I found that the rivets closest to the bulkhead can’t be back-riveted due to the bulkhead interference with the gun, so I buck those last 4 on each side.

Progress was very slow as I decided to rivet these in small batches. Lots of adjusting and fiddling to get everything on just the right angle. But it was time well spent as they all came out looking good.

Today I riveted the aft fuse top side skins to the F-01406L and R bulkhead. This was straightforward, although the only way I could get the rivet beside the seatbelt lugs was to back-rivet. This necessitated using the little table and fiddling around to position the fuselage in exactly the right place. I had to redo a couple of rivets, but mostly these came out looking great.

Last night I decided to build a small table to support a back riveting plate, so I could try to back-rivet the #30 rivets holding the seatbelt lugs to the top skin. I found some scrap plywood and 2×4, and with some trial and error made a little table.

Tonight I tried it out, and was able to quickly and easily backrivet both lugs… except for the inner-most rivets on each side. They are too close to the bulkhead, and with the skin angles, I couldn’t get my backrivet set onto the rivet head. So I decided to buck those with the gun and bar, and it went fine. The problem is, I damaged the next rivet over in the process. These rivets are all close together, and I just wasn’t thinking. I ended up repeating the mistake on the other side before realizing what I had done. So, now I am going to remove one of the rivets on each side and redo them. It sucks trying to remove these fully-installed rivets, because it’s hard to get a grip on the now mangled shop heads.

I’m going to call it quits for tonight and try to get these tomorrow.

Today I riveted the two rivets I missed last time, securing the seatbelt lugs to the F-01406C bulkhead. I used an offset rivet set, and found I needed to tape both my tungsten bucking bars together to have enough mass to set the rivets without using a scary amount of air pressure on the gun. I had the gun set to 35 PSI, and that worked great. The rotisserie made this so easy, I quickly rotated the fuselage to either side before setting the rivets. It made for easy access, and both rivets were set with no problems.

Then I moved onto the next step, riveting the bulkhead to the top skin. I was able to reach every rivet with the hand squeezer, and set them all quickly and easily.

By now it’s too late in the evening to use the rivet gun, so the next round of riveting will wait until tomorrow.

Tonight I worked on installing the upper seatbelt lugs. I was able to squeeze 3 of the 4 rivets on each side, but the last, outboard-most rivet will need to be set with an offset attachment using the gun and bar. It was too late in the evening to make that kind of noise tonight.

The rotisserie was super helpful, and the clearances were good, but rather tight. overall I’m pleased with how it’s working out.

Tonight I riveted the seatbelt lugs together, then clecoed them to the fuselage. I had to clean and oil my hand squeezer. It’s been so long since I used it!

I didn’t have too many problems once I had the right yoke on the squeezer, and fiddled around to find the right angles.

Tonight I started working on the shoulder harness seatbelt lugs. I separated, deburred, countersunk and then primed the few parts.