Dave’s RV-7A Building Log

I messed around with the EFIS and EMS a bit more. I figured out how to transfer the setup files onto an SD card so I can edit them on the computer. Much easier than going through all the setup screens.

After reading the install manual again, I realized that I forgot to connect a ground wire to the case. The forward hatches are already paying off. It was a little tricky to string a ground wire to each unit, but it would have been impossible without the hatches. Now the EGT (exhaust gas temp) and CHT (cylinder heat temp) sensors seem to be working. All the other sensors seem to be working, but it’s a little difficult to tell at this point. Fuel and oil pressure are both zero, for example. One minor issue is with the aileron trim servo position. It doesn’t seem to be working. I’ll have to debug that further–maybe after I attach the elevators. That way I can see if the elev trim servo is working and compare the two.

I did a little bit of other wiring tiding up. I secured the wires behind the screens and coiling up an extra unswitched audio input. I was planning on using it for the EMS, but the audio warnings will all come out of the EFIS.

My next task was to make an attempt at filling the cowl pinholes. In order to reduce weight, Vans doesn’t put a gelcoat on the outside of the cowl. That’s great, but instead there are literally millions of tiny pinholes all over the fiberglass. It’s not strictly necessary to take care of all the holes before flying, but I wanted to at least get it looking a little better. Plus I think it’ll clean up easier later if the holes are filled.

The instructions say to paint on some epoxy that’s been thinned down 50/50 with acetone. I gave that a try after rough sanding the cowl surface and cleaning with lacquer thinner. The mixture paints on easily, but immediately turns kind of gooey on the cowl surface. Some of the pinholes got filled, but not all of them. I tried using a plastic bondo spreader to sort of push the epoxy into the holes, but that didn’t really work. I decided to just let it be, and it’ll hopefully look better after some more sanding and possibly a second coat.

The EFIS (electronic flight instrument system) and EMS (engine monitoring system) arrived. I headed home a little early and shot a coat of high-temp paint on the inside of the bottom cowl.

Then it was time to play with the toys. Of course the screens didn’t fit into the panel. The screens are dead on to the dimensions they promised. The problem was the panel cutting (again). I filed and filed and sanded and sanded and eventually got them to fit.

I plugged all the connectors into the back and made an Ethernet cross over cable so the units could talk to each other. Shazam! They worked right off the bat. I don’t have the remote compass hooked up yet, but that’s next on the list. I had a bit of a difficult time getting a good picture of the screens. Without a flash they wash out, and with they don’t look very bright. I’ll have to pull out the SLR. Trust me, the screens look awesome in person.

I finished up attaching the seal material to the bottom cowl. I thought that was going to be the end of the work session. There was a community meeting about the Renton airport that I tried to attend. The parking lot and neighboring streets were absolutely filled. Couldn’t find parking anywhere. I headed home and worked on the project some more.

I prepped the inside of the bottom cowl for paint. My plan is to spray on some white high-temp enamel. I roughed up the surface with some 60 grit, cleaned it all with lacquer thinner, and taped the edges.

I next decided to work on the wing tips a bit. I trimmed the aft end to match the wing+aileron depth. It only needed about 1/4″ trimmed off. I then drilled the holes in the wing tips to the reinforcing strips. I’ve been debating on whether the strips are really necessary since I’m going to be using screws and nut plates. They certainly won’t hurt, so I’m going to use them. I followed the parts list from Cleaveland’s wing tip screw kit and ordered some 426A3-6 soft rivets, but they are way too long. 3-4.5 will work much better.

The final thing I did was to strip 40″ of shielding off of some coax I had left over from wiring the plane. I put a female BNC connector on the other end. Marker beacon ready for installation.

I timed the P-mag, which is a really simple operation. I applied power to each unit without enabling them. That puts them in setup mode. I put the prop at TDC #1, and then blew into the manifold pressure line twice. Done deal.

I pulled each of the spark plugs and verified the gap. I adjusted them all to .030″. I then tested the spark from all of the plugs. They are all sparking and in the correct order. One minor weird thing is that the two P-mags are perfectly in sync for one set of spark plugs, but off slightly for the other set. Not a big deal.

While the guys were over yesterday, I noticed that I forgot 3 firewall rivets on each side. Took care of that.

I messed around with attaching the baffling material to the cowl. It’s meant to bridge the gap from the cowl to the baffles. I put the bottom cowl on to make sure the size was correct. I saw no reason to use the baffle pop rivets, so went with CS4-4. Unfortunately, I countersunk one hole too much, so put some JB Weld into it and I’ll finish them up tomorrow. I hate countersinking.

Once it warmed up a bit, I shot some paint onto the front spar covers.

Not a super productive day, but I’m still recovering a bit from last night.

Not much work will transpire on the plane this weekend. It’s Boat Show Weekend. A few of us guys have had a tradition for 6-7 years of checking out the boat show and pub crawling through Seattle. It’s one of the few events that would pull me away from the project at this point.

I did get a few things done this morning before hitting the show. I prepped the spar covers for paint. I’m hoping they are the last thing I need to paint.

I also installed a seal material to the flange along the bottom of the canopy. It’s a seal material that Dan C recommended a while back.

I did a little bit of other tinkering, but that was about it.

The sun was still out when I got home, so I asked Julie to help me with the canopy. We rolled the plane outside, this time used a screwdriver to help remove the gas struts, and took off the canopy. No sweat.

While I had the plane outside, I put the data cards in the 430W and fired it up. Took only about 2-3 minutes before the GPS found itself. That’s re-assuring.

Next I crawled in the cockpit and worked on attaching the aileron trim motor. The budget method used by Vans is some .040 safety wire. I did a trial run first, just twisting the wire a few times by hand. Seemed to work OK. I then made some nicer looking ones with the safety wire pliers to the same length. One minor problem is that the instructions have you move the stick full left and forward. Well, I don’t have the elevators or ailerons hooked up, so I had to estimate that part. I think I got it to the point where there’s light spring tension in all trim positions without any slack on the springs. Works pretty good.

Next up was the seat harnesses. I quickly found out that the fatter bushing on the Hooker lap bolts are going to need a longer bolt, AN4-7A instead of AN4-6A. I only had one bolt that was long enough. I did get the shoulder and crotch straps installed. Looks pretty good.

I wrote to Hartzell to ask what RPM restrictions I should have for my engine/prop combination. They haven’t tested my exact configuration, but I know they’ve tested some 180hp engines with electronic ignition. Well, they wrote back and said I don’t need any RPM restrictions/placards. Very cool.

Discussing this further with Gus at Vans, he said Hartzell is probably just acknowledging that they haven’t tested my exact combo. Hmmm.

I finished up the GPS antenna mount, although I need to order some screws from Spruce for the antenna itself. The mount attaches to the bottom side of the right forward hatch via some #6 screws and nut plates. I also made the patch cord from the GPS to the antenna. Thanks Jim for ordering the special connector. It worked great.

I was looking over someone’s blog lately and saw how they safety wired the front spinner bulkhead. Which made me wonder if I had done that. I removed the spinner, and sure enough the bolts weren’t safetied. Took care of that.

I thought about draining the preservative oil from the engine, but decided to wait a few more days. It’s an easy task to swap out the oil. I might as well wait until I’m really ready to start up the engine.

Most of the things I want to work on are inside the cockpit, but I can’t open the canopy inside my garage. Rain prevented me from rolling it outside and removing the canopy. We’ll do that tomorrow or this weekend.

I’m still waiting on the stupid screens from AFS. I’d like to get the remote compass mounted and the static/pitot lines figured out before taking the plane to the hangar.

I verified the size of the wire cut out in the rudder bottom tip, enlarged it a bit, and then attached the tip to the rudder with pop rivets. The empennage tips are now all attached.

I moved on to the cowl camlocs. Milspec was very cool about swapping out the -3S studs that I got in the group buy a while back with shorter -1S studs. A+ on customer service. I figured out how to put the pin back into the adjustable camlocs along the bottom. I screwed back the camlocs a ways and then put the -1S studs into the cowl. They are a little tricky to put in. The collar on the stud tends to slip down into the craw of the tool. I got all of the bottom and top studs put in and the cowl re-attached. She looks very plane-like with all the various parts attached (minus the wings of course).

I re-adjusted all the studs flush with the cowl surface (or actually just slightly proud), removed the cowls, and pulled the pins from the camlocs. Done deal. I’m glad I went with the camlocs. The cowl is very easy to install/remove with these things.

I still had some time left in the evening, so I started working on the GPS antenna mount. I’m going to put it under one of the fiberglass forward hatches. I made a little shelf that I’ll attach to the hatch. Only got part way through the fabrication.

I’ve been putting in a lot of hours lately (for me). It feels like I’m in the homestretch and I’m sprinting for the finish line.

I had no idea when I started the empennage fairing that it would take so long to finish. Tonight I countersunk the holes in the fiberglass fairing, attached nut plates to the fuselage, trimmed around the aft end of the fairing, and trimmed the gap covers that go underneath the horizontal stabilizer. In the process I had to remount the HS (again). I think it is now finally done.

I started messing around with the bottom rudder tip again, but didn’t get far. I just need to enlarge the hole for the wiring a little bit and then I can pop rivet it in place.