Dave’s RV-7A Building Log

I completed the wiring for the right ignition switch and now I’m out of the clear 1/8″ shrink tubing I’ve been using for wiring. I have a bunch more showing up on Wednesday from B&C. I’ll have to work on something else for a day or two. By the way, I’ve been testing the switches as I hook them up. I use a continuity tester with one end on the fuse block (or ground), and the other end connected to the item being powered (or grounded). I then make sure it’s working correctly as I flip the switch. I don’t have any fuses in the fuse blocks yet, so nothing is actually getting power. Soon.

I pulled out the airspeed indicator (ASI) and altimeter and decided to get them fitted. I knew that the spacing with the Digiflight in the middle was going to be a little tight with the Nulite rings. They say you can take a Dremel to them, so I trimmed a bit (about 1/16″) off one side of each with the belt sander. The ring got pretty warm, so I sanded a bit, paused, sanded, etc. Turned out perfectly. The instructions on the web site say to paint the exposed area with some white acrylic paint, so I still need to do that.

I was going to mount the instruments, but figured out I need #6 screws not the #8 that I ordered. A #8 fits through the holes, but there’s no room to put the nut on. I guess we’re just supposed to know that instruments need long #6 screws. I just placed a big hardware order at Spruce today. It always seems like I end up needing something the day after I place an order. I’ll see if Lowes has some screws that will work temporarily. I want to get everything test fitted into the panel to make sure there are no interference problems.

I spent a little time re-verifying all of the fuse and wire sizes I figured out previously. I don’t want to run the wrong size wire at this point.

I wired the left ignition switch. It’s kind of complicated as a wire needs to run from the fuse block to the switch and then to the P-mag. And then another wire runs from the ground block to the switch and then to the P-mag. And I’m putting labels on both ends of each wire. It’s time consuming, but progress is in the forward direction.

Organized the wiring behind the switches a bit, including shortening one wire and replacing another. I temporarily used some clothes hangar wire to get the switch wires routed how I wanted them. I also soldered the leads onto the starter switch.

Geoff Sharples, a Technical Counselor from the Seattle EAA Chapter, stopped by for an inspection. He said everything looked great. He pointed out a couple of cables and fuel lines that need to be clamped away from the engine mount to avoid chafing. That’s kind of my last step on the firewall forward is to secure everything. We also spent a little time trying to figure out a minor issue with the throttle control. For some reason, there’s kind of a detent about 1/4 of the way up from idle. I knew the problem was there, but just hadn’t gotten back to looking at it. It seems like the swivel joint at the end of the cable is somehow causing the issue, but I’m not sure how. I’m not excited about the prospect of having to remove the cable to look at it. It’s at least a 2 hour operation whenever I touch that stupid throttle quadrant. He looked at the fuselage construction, and said it all looked good. I have him back one more time, possibly down at the airport when it’s all set to go.

The wiring around the fuse blocks was getting to be quite a mess, so I decided to organize it. I drilled some holes for tie-wrap mounts and carefully routed wires around.

There’s about a hundred different wiring tasks I could work on now. I decided to get the more difficult/unpleasant stuff out of the way first. That would be the alternator. Working with the thicker 6 AWG wire is not as fun, and routing stuff forward of the firewall is always tricky. I ran a wire from the alternator back to the panel for a circuit breaker and then from the panel back to the main bus. I haven’t decided exactly where the circuit breaker is going to reside yet, so I left those ends long for now.

I also hooked up the alternator field wire to the switch on the panel. The connector on the Vans alternator is very goofy. The only way I could figure out how to attach the two wires from that connector to the wire running aft was to use a Molex connector. It’s odd to have two connectors in a row, but the Molex connectors are much easier to aquire and use.

The tangle of wires is getting a bit crazy. It’s time to do some organization and tie-wrapping.

The parts I needed finally arrived from SteinAir. I was able to hook up the master contactor to the main bus with some #6 wire. I also wired the master switch to the contactor and ground. Flip the switch and bingo. The contactor energizes and juice is flowing. I have to be careful now that I have +12V running around the plane. For example, I don’t want to accidentally fire the starter. I think I’ll leave out that fuse until I get to the hangar.

So to recap, I have 1/2 of one switch wired so far and I have 10.5 to go. The others should go quicker, though.

A side note on comments. I’ve decided to disable comments on posts. 99.9% of it was spam, and I’m tired of dealing with it. If you have a comment on a post, just shoot me an email using the link in the right sidebar.

I installed a 3/4″ fitting from EPM.AV in the firewall for passing wires through. I should be more fire-proof than just a snap bushing and RTV. It was a bit difficult to install. Drilling through stainless steel is never fun. And it also doesn’t provide any anti-chafe protection for the wires. Hopefully there will be enough room after wiring to jam some firesleeve in there.

I was originally planning on using a 3/4″ fitting for the engine sensor wires and 1/2″ fitting for everything else. However, it quickly became obvious that 1/2″ was not big enough for anything other than a wire or two. I’ll return that one for another 3/4″.

With the fitting in place, I can now run wires through the firewall. I started by running wires for the starter contactor. The electrical parts I ordered from SteinAir 2 weeks ago should finally arrive tomorrow so I can hook up the battery and finally start turning stuff on.

I spent most of today down at the hangar getting it tricked out. I’m going to hire somebody to put in drywall, but wanted to add a few outlets first. Running metal-clad wire is not fun, but it’s a commercial building. I also spent a while down at the pool enjoying the sunshine with Adele on her last day of summer vacation.

I found a little time to work on the plane. I figured out the best location for mounting the fuse blocks. I drilled #12 holes and temporarily put some bolts in there. I’ll order some screws that have a smaller head for permanently mounting them.

I didn’t get as much done over the 3-day Labor Day weekend as I had hoped, but I had some excellent time away from the project instead.

I guess some builders simply use star washers to keep their switches from rotating, but I like the keyway washers. I made backing strips from .063 sheet with dimensions from Aeroelectric. It worked perfectly. On the second strip I made one minor change that worked better. Instead of drilling a 1/8″ hole for the keyway washer, I used a #36 drill bit. It’s just big enough and doesn’t allow the switch to turn as much.

I temporarily mounted the switches so I can wire them up. I also made labels, so I don’t get confused. I like the blue tape look. Maybe I’ll just use that for the final panel (not).

I also ran the headphone and mic wires for pilot and copilot. I debated quite a bit on where to locate the jacks. The place I was originally going to use will be covered by my fancy side panels. Looking through the Aircraft Spruce catalog, I found some flush-mount housings that will work out great. The jacks will be right under the arm rest and just aft of the seat.

I ran the pitch servo wire back through the plane. It was a little difficult to get it through the F-704. I used some tubing to keep the pins together. There’s a little slack in the wire, which is perfect. Better a little slack than not enough.

When I had Ross make the panel, he made the hole for the starter switch undersized. I wasn’t sure what size hole it needed. Turns out it’s the same as the other switches. Looks pretty cool.

I also ran more of the wires up and down through the shelf. It’s starting to be an actual wire bundle.