Dave’s RV-7A Building Log

Worked on drilling the holes for the fuel tank attach bracket. It was a lot of monkeying around with the various parts to get them lined up. I then disassembled the parts and deburred them. That was the main point of doing it now. The holes for the bracket could be drilled later, but then I wouldn’t have been able to deburr the holes.

I also cut the holes for the fuel line grommet in the side skin with a corresponding slightly larger hole in the doubler. I had trouble figuring out how to cut the 1″ holes. The largest Unibit I have is 7/8″. I didn’t want to use the fly cutter in a hand drill. I didn’t have a 1″ hole saw. I tried using a spade bit. Big mistake. Aluminum is too soft and the center cutter wandered off. I stopped it before any serious damage was done. I ended up getting a 1″ hole saw (thanks Julie), which worked much better.

I’ve also been contemplating whether to put firewall sealant on while riveting the fuselage or to wait until later. It seems to me that the sealant should go on the firewall flange. That doesn’t get riveted until the cowl hinges are installed. I think I can squeeze some sealant in there later when I actually rivet the firewall flange.

I’ve also been debating about whether to install the control column mounts now or after riveting. Dan C installed them later for better riveting access. But then it’s difficult to properly install the control mounts. Considering how important the mounts are, I’d rather install them perfectly now and use a couple of pop rivets on the bottom if needed.

In the process of figuring out the control mounts, I also discovered that there are four bolts on the cover brackets that I haven’t installed yet. Much easier to do that now. Tomorrow I’ll disassemble the forward fuselage, install all of that and then hopefully put it together one last time.

I’ve been busy with other projects and activities this week and haven’t had much time for the plane. My main goal is to get some riveting done on the fuselage this weekend with Julie. That should be doable.

I mainly fiddled with the fuel tank attach area. I drilled out the bottom hole to #10, dimpled the skin, and countersunk the lower longeron. A countersunk screw goes in this spot.

I think I’ll also drill out the holes for the tank attach bracket. I might as well do it now while I can remove the parts and properly deburr them and clean out the chips.

Removed the left side skin and did a little more tweaking. I adjusted the F-705 flange and added one more rivet around the spar opening. Half the fun of plane building is taking things apart and putting them back together again about 5 times, right?

Following that, I started re-assembling the forward fuselage including the firewall and associated extra longerons. It’s cool how the parts just snap together. The dimples fall right into the countersinks.

I decided to take off the right side skin and do some tweaking. The bend at the corner rib was better than when I originally fit the skin, but it still needed some tweaking. The bend in the left skin looked really good, so I worked on the right skin until it worked a little better. This picture shows the bend on the left skin. You can see a little dip, but I think that will pull together during riveting.

I also tweaked the F-705 flange. It didn’t seem parallel to the skin. I also set one more rivet around the spar cutout. According to Dan’s site, the bottom aft rivet can also be set in advance. After all of that, I put the skin back on again. Being Valentine’s Day, I didn’t want to spend too much time in the garage. I made dinner instead.

I had one more thing I wanted to do before starting re-assembly. One of the longerons didn’t have enough twist in it. I put it back in the vise, and the twist was only 7 degrees instead of 17. Along the curve, there was a subtle twist of 10 degrees in the wrong direction. I worked on it a little in the vise with a Crescent wrench and got the twist along the curve straightened out which brought the twist at the forward end back to 17 degrees.

I started re-assembling the fuselage, pre-riveting parts along the way as called out in the instructions. I ended up going back to the original assembly instructions to remind myself how to put it all together.

This is a cool (and large) animation that shows the process.

Painted some of the interior parts and skins. I figured out what will show and only painted those areas.

Cleaned a bunch of parts and skins in preparation for spraying some interior paint.

Dimpled the forward bottom skin and the forward and baggage bulkheads.

I’m going to try to paint the interior parts before I put them together. The only disadvantage I see to this is that the rivets won’t get painted and I might scratch the paint during the rest of the aseembly. That doesn’t matter too much to me as I’m going to get one of the interior upholstery kits. I used a Scotchbrite pad to scuff up the parts and skin areas that will show in the cabin.

Dimpled both forward side skins with the C-frame.

Deburred the edges of the left forward side skin and deburred the holes on the other side. I also took the squeezer and dimpled the holes around the edges.

Looking more carefully at the plans, I discovered that the lower hole of the forward tank attach needs to be drilled out and dimpled/countersunk for a #10 screw. I’ll do that when I put things back together.

The last thing I did was attach nut plates to the F-902 bulkheads, and the horizontal baggage wall stiffeners. The vertical baggage stiffener doesn’t get nut plates installed until one of the covers is on.

Looking over my list of things to do, I basically just need to get out the C-frame and dimple the rest of the skins. I’m getting close to putting this thing back together.