Dave’s RV-7A Building Log

One thing keeping me from riveting on the middle top skin is the remote compass mount. I wasn’t sure how big it needed to be. I asked AFS about it, and the dimensions are in the premliminary install manual. I made up a mount out of .040 sheet and temporarily installed it. I’ll probably end up using #8 brass screws (non ferrous) in some oversized holes so the mount can be adjusted a tiny bit to get it exactly in the same pitch and roll plane as the AF-3400 screen.

I also worked on the firewall wiring fittings. I installed them permanently with some #6 screws and the goop to seal them to the firewall

Spent a little time sorting and routing the sensor wires firewall forward and practicing my adle clamp skills. I don’t care for adle clamps, especially stacking up two of them. The routing of the wires is looking pretty good so far. I also hooked up the oil pressure sensor. In the picture, it looks like the wires are blocking the oil filter, but they’re not. They are a little bit in the way, but getting the filter on/off should still be easy.

Carl from NZ and I split an order of screws of various sizes from McMaster-Carr for securing stuff to the firewall. They are a socket cap head with a black oxide finish. They look really good.

I also ordered some seal material that DanC recommended on the canopy side rails. Looks like it will work well too.

I spent a little time looking over the rivets in the left wing from the last riveting session. A couple of them got horked up, so I drilled them out. Bucking access is not good and I was in a bit of a hurry. Haste makes waste. I also prepped the access holes for nut plates, but didn’t install them yet.

I’ve put this step off for quite a while. I’m always nervous about drilling through the firewall, but this is the best spot for the sensor wires to pass thru. It’s high enough that the battery can still be removed, and on a fairly direct path between the engine monitor and the sensors. I’m using the fitting from EPM.AV.

I had just a little time for the plane while Adele was playing with her B-day presents. I verified the layout of the panel labels, and tweaked things a bit more. I also gave the panel one more overall sanding in preparation for taking it to the powder coater tomorrow.

I didn’t do much on the plane. With Halloween and Adele’s birthday this week, it’s going to be low on the productivity. I sanded down the filler on the panel, but it still needs one more good sanding overall. I also messed around with laying out some panel labels. For some reason Visio seems to think 1″ = 7/8″. Handy (not).

To finish up the right wing, I did the service bulletin for the fuel pickup. A putty knife made pretty quick work of the access cover I Prosealed on 2 years ago. The inside of the tank still smelled of fresh Proseal. Ah, the memories… Drilled the pick-up nut and safety wired it. Instead of wrapping the wire around the fitting (which seems goofy) I drilled a tiny hole in the anti-rotation bracket. It took a little while to clean up the proseal with a putty knife and sandpaper. I didn’t Proseal the cover back up yet, as I’m waiting until I do the other tank.

Julie helped me put the right wing back in the dolly and turn the whole thing around. Time for the left wing. I started by installing the rest of the tank nuts and screws.

While waiting for some riveting help, I started working on the engine management system (EMS) harness. I drilled a hole in the subpanel for a snap bushing, but I’m still debating on the firewall penetration. Above the battery seems to be the only logical place. I’ll place it as high as possible to make battery removal not entirely impossible.

I also sorted the EMS harness into don’t need (carb temp, etc.), aft of subpanel (trim indicators), aft of firewall (amps, fuel level), and firewall forward. I hooked up the wires to the amp shunt and capacitive tank sender converters. (Don’t let the paper cut-out fool you. I still don’t have the glass panels yet. Besides that’s the back of the panel.)

Lots of progress all over.

Big day today. I started running the EFIS wires around a bit more seriously. I discovered there were two black wires, when I was expecting one. The shorter one didn’t seem to be connected to anything and then I figured out it was the shields for the communication wires. It’s supposed to be connected to a ground. I’m sure there’s a better connector housing out there (i.e. not plastic) that the wire could have been connected to and then it would have been automatically grounded.

I debated quite a bit on how to hook the various wires from the avionics harness to the EFIS harness. In the end, I decided no intermediate connector would be best. I tore apart the EFIS harness a bit, removed the appropriate wires/pins, crimped pins onto the end of the avionics harness wires and integrated them into the EFIS harness. Worked out really well. I attached the EFIS altitude output to the transponder, the serial line to the GPS, and the audio output to the audio panel. There are a couple of extra wires I’m not using right now. Instead of removing them, I put shrink wrap over the ends and coiled them up. The only wire not connected yet is the flap position contact for the AOA.

As long as I was working on wiring, I ran some wires to the F-704 covers for the cabin lights and connected them to the dimmer. I also connected the capacitive fuel sender converters to power and ground. I decided to put them on the avionics bus with the EFIS and EMS. I also ran some wires to the EMS area for power and ground. I guess I’ll be making mine own connector for that, which is just fine.

On top of all that progress, Julie was ready to finish off the right wing bottom skin. Adele had a friend over playing, so what could be more fun than riveting on a Saturday night?!? We got it finished off. Woo hoo! One down, one to go.

Installed the shunt for reading the current from the alternator. I didn’t really plan for this very well, but it worked out great. I removed the wire from the fuse block, positioned the shunt so that the wire reached perfectly, drilled it to the firewall, and made a short jumper going back to the fuse block.

After reading the directions carefully 3 times, I drilled #30 holes in the exhaust pipes for the temperature probes. The instructions say that 3″ is ideal, but there’s a joint in the #1 pipe at that point. I moved the probe up to 2.5″ and tried to position the other probes the same distance from the exhaust flange. The curvature of the pipe on #2 made it a little difficult, but it’s within 1/4″.

I started routing wires from the EFIS harness yesterday, but then became concerned that the EFIS/EMS box might be too deep with the connectors installed. The dimensions on the web site says it’s 5.5″, which leaves just enough room for the wires to bend out of the way of the subpanel. With that resolved, I routed the outside air temperature (OAT) probe wire out to the left wing and the remote magnetometer (i.e. compass) wire to the rear of the fuselage. I’ll mount the magnetometer at the top of the F-707 bulkhead. That will put it well out of the way of anything ferrous except for the harness cables, which I’ll degauss. The OAT probe will go on the bottom of the left wing.

I did some more head scratching over the fuel flow sensor. According to AFS, mounting the sensor close to bends in the line isn’t a good idea. My new preferred location is in the line from the mechanical pump to the fuel servo. I can get the Stratoflex line cut, new fittings installed, and then mount the sensor in the middle of it wrapped in firesleeve. The EI documentation indicates it can be installed in flex line as long as it’s within 6″ of a support. This picture shows the spot I’m thinking of.

I also identified the 6 or so black wires in the EMS harness. They all connect to a common ground, but I decided to actually identify each one based on the pin it’s connected to. I might also remove several wires that I don’t need, RPM sensor power/ground, tank level 3/4, and flap position. It looks like I’ll need to move the tach wire from pin 32 to 33, but I’ll confirm that first.

I’m still trying to figure out how to hook up the manifold sensor. I wrote to Emagair to ask what kind of tubing they included with the P-mags. It’s a high temperature silicone tubing. I looked it up at McMaster-Carr and it sounds perfect. The thick wall 1/4″ tubing is rated to 15psi and 500°F. Perfect.

EAA 1440 meeting last night. Terry Burch talked about building challenges and first flight issues. Very interesting stuff. I’m thinking about using him for my first flight. He has a ton of RV experience.

I received engine sensors, wiring harnesses, and AOA kit from AFS. Woohoo! Everything looks top notch.

I started by installing the cylinder head temp sensors. Those went in very easily. Next was the oil temp sensor, then oil and fuel pressure. I also started running some wires from the EFIS harness around.

I spent some time trying to figure out where to install the fuel flow sensor. It’s a red aluminum block made by Electronics International. I went on their web site and found some more info on mounting. It can be mounted with any of the following sides (or combination thereof) pointing upward: wires, cap with 5 screws, outlet. There weren’t any restrictions mentioned about straight tubing before or after. If that’s the case, I might install it on the vertical run of tubing up the firewall on the cabin side. Second choice would be right after the mechanical pump.

The other challenge is the manifold pressure sensor. I need to run the manifold pressure from the 1/8″ NPT fitting on the cylinder to the 1/4″ barbed fitting on the sensor AND to the two 1/8″ barbed fittings on the P-mags. I’m thinking about using an AN840 fitting on the cylinder with a mini clamp and then running Tygon tubing to the sensor and P-mags via some T fittings. I’m just not sure about attaching plastic tubing to an engine fitting. Tygon is supposed to be abrasion and chemical resistant, and handle temps up to 200-250F. I’ll figure out a way to restrict the flow through the AN840 fitting just in case the tubing ever does burst.