Dave’s RV-7A Building Log

I worked quite a while on smoothing the edges of the seat ribs and lightening holes. Next I squared the flanges and fluted the bottom flange. The other flanges look straight, so I don’t think they need fluting. I started fitting the ribs to the center section.

I made one mistake along the way when cutting the center seat rib flanges for the wiring conduit. I cut away too much of the flange and left a very small edge distance for one of the rivets. I’m trying to decide whether to just order new parts or to leave it as is. There are 4 other rivets and two bolts holding the rib to the bulkhead, so I don’t think it’s much of an issue. Versus $17 each for new parts and peace of mind. I’d hate to have that little problem trip up an inspection later when the ribs are a permanent part of the plane. [I went ahead and ordered replacement parts.]

I also pulled out the baggage ribs and started looking at those. The instructions call for a 1-5/8″ hole in two of the ribs and the plans call for 1-1/2″ for the steps. Since the tube on the steps is already 1-1/2″, I went with the larger dimension. It’s very cool that they pre-punched a pilot hole for it. I whipped out the fly cutter and cut the holes.

The aft bulkheads are waiting for priming, which means I need some nice weather. I also decided to wait on bending the longerons until I need them. They take up a lot less space when they’re straight. So I moved on to the center section.

I fabricated the spacers.

I then pulled the seat ribs off the shelf and started working on trimming them as outlined on the plans. I have two tips for the ribs that get cut open. First, don’t throw away the little part you cut out. You actually need it. I almost really screwed that up. And secondly, drill the little part that covers the gap before you cut the rib. It’s just easier that way. Other than that, the rib trimming is pretty easy. I took the picture right after I did the rough cut, but before I cleaned it up.

I can see there is a lot of deburring coming soon: seat ribs, baggage ribs, and there’s still more parts on the shelves. I thought the boring deburring was mostly done when I finished the wing ribs.

I wasn’t too productive. I mainly read over the longeron bending instructions and made some measurements. I need to get the hard top for Julie’s car out of the garage before I can do any work with the longerons. Plus, I’m not sure what the point is of bending the longerons now. They’ll just take up more space, and I don’t think I need them for at least a few more weeks.

I did some measuring and trimming on the aft canopy deck parts. Different trimming is required for a tip-up vs. a sliding canopy. I noticed from the plans, that it’s better to do some of the trimming later, after back-drilling to the longeron.

Time for some tool maintenance. I bought a new belt for the belt sander and a new blade for the band saw. I went back to a 3/8″, 18 tpi band saw. I was using a 1/8″, 14 tpi for a while thinking the narrower blade would make it easier to cut tight corners. Instead it was more prone to bending. The thicker blade is much better for control and the extra 4 teeth per inch really make cutting easier.

With all of the bulkhead stuff done or waiting for priming, it was time to move onto the longerons. I pulled them down from storage and started reading through the instructions.

Finished drilling, deburring, dimpling, and countersinking the tie down for the last aft bulkhead F-712. I dimpled everything except the tie down, which I countersunk since it’s the thickest part. Now the remainder of the aft bulkheads are ready for priming.

Went back to riveting the cover brackets on the center section. Also made the place holders for the wing spars. It was kind of fun working with wood for a change. I glued up two pieces of 3/4″ wood a while back, so I just had to use the belt sander to trim them down to 1-7/16″. That took longer than I expected, probably because the belt sander needs a new belt. I also loosely bolted on the spacers and control mounts using the correct hardware. I just didn’t tighten anything down yet.

Finished deburring and drilling the F-708 bulkhead. I drilled the optional wiring holes and the holes for securing the static line.

I deburred and fluted the F-707 bulkhead and clecoed it together for drilling. I’ve also been drilling out all of the optional snap bushing holes. It’s easier to drill them out now than later. And if I don’t use them, it’ll just be extra lightening, right?

I also clecoed together the F-709 and F-710 bulkheads, drilled everything out, and deburred.

I deburred another couple of bulkhead parts, and then worked on the F-711 bulkhead. I tapered the bars, and then drilled them to the bulkhead. I then disassembled it and deburred the holes.

I’m sort of just randomly jumping around now finishing up the aft bulkhead stuff. I fabricated the rear tie down and looked ahead in the instructions. It looks like I have just a few more hours on the aft bulkhead and I will be ready for another batch of priming. Too bad the weather looks like rain all week.

I deburred a few more bulkhead parts, thinking I was almost done with that. Then I found another pile of bulkhead parts. Fun.

After I had enough deburring, I riveted together the F-706 bulkhead. Despite trying to be careful, I riveted on the F-728 when it’s supposed to wait until later. No big deal to drill it out. I took the first two pictures before I discovered my mistake.

I then worked a little more on fabricating angles for the aft-most bulkheads.

(Edit: Although it may be tempting to rivet the angle to the F-728 bellcrank channel, wait until later. There are some holes at the top of the F-706 bulkhead that need to be back-drilled, and it’s much harder to do that with the angle in the way. See the 3/14/2005 entry.)