Misc Wiring

TIme: 1.0 hr

I received some wire and wire sleeve that I ordered so I finished up a few things. I put some wire sleeve around the wires in the fuel pump to protect them from rubbing on anything in the fuel pump box. I also finished running the wires for the turbo boost and warning lamps. For these I cut off the connector on the wire coming from the engine and then used a solder sleeve to extend the wire. The lights will be mounted on the instrument panel on top of the PFD next to the Servo ISO switch and Reversionary switches. Lastly I ran the 8 or so 22AWG wires from the VPX for the various switches.

Sorry no photos


Avionics Wiring Continued

Time: 4 hrs

Over the past fews days I finished up most of the wire runs for the avionics that I’m mounting on the shelves and rib. I also terminated all the grounds to the main grounding block. I’ve been trying to understand the way Garmin has set up the grounds on the avionics. It seems like most of them have redundant grounds. I’m not sure if it’s just for redundancy or if they actually need to be connected to function properly. It seems like a few actually do need the multiple grounds connected like in the case of the transponder, but most seem to be merely for redundancy. I’m planning on only doing redundant grounds on the “essential” equipment since I’ll probably run out of connections on my ground bus.

I’m going to get the connector kits for some of the avionics so I can start wiring them up. I don’t have the money right now to get all the avionics that I need so with the foam mockups and the connectors I should be able to get everything wired up. When I do get the avionics it should go very quick getting them installed.

I’m also wondering if I need to wire in connectors for the avionics that will be mounting to the instrument panel. It seems like it would be good to do so that the whole panel could be more easily removed, but I don’t want to add in more potential points of failure. I guess I’ll need to think about it a bit more.

Avionics Wiring

TIme: 3hrs

I feel like I’m not getting anywhere on the build, but I know things are getting done. I spent some time today organizing the wiring as well as running a few more wires. I also wired up the connector for the TCW battery backup and extended the wires for the TCU. Next on the list is to connect all the ground wires I have to the ground block on the firewall.

I cut the ring thermals off the TCU wires and soldered extensions onto the wires. Power will go to the VPX and Ground will go to the main ground bus on the firewall. Those other connectors are for the Turbo Boost and Warning lamps. I may do the same for those and cut the connectors off and just extend them.

Believe it of not this is organized. I have all the main cabling run up through some adel clamps and all the sheathing is cut back. Wires are bundled for what device they will connect too. The next big job is getting that pile of ground wires terminated and connected to the main ground bus which is behind the rib, so not super easy to get to… hence me not really being motivated to do it. I’m still wondering how I’m going to run the wiring for the shield grounds. There’s a few of these shielded wires that I need to ground the shields and the VPX doesn’t have screw terminals to attach them to the jack covers (like the Garmin stuff does). I’m thinking I may just ground them to a screw on the rib… there’s no real issue with causing a ground loop since the other end of the shield isn’t terminated.



Time: 3.0hrs

Over the past few days I did a few miscellaneous items on the plane. I’m waiting on a few small parts so that I can make better progress, but there’s still lots to be done even without the needed parts.

Things done today:

  • Mounted GEA24 and TCW battery backup
  • Finished up carpet on copilot and pilot areas
  • Torqued bottom oil pump bolt
  • Torqued a few of the oil line fittings
  • Installed safety wire on fuel pump bolt
  • Cleaned up some wiring
  • Made up a small circuit board to hold the components needed for the RPM and Oil Pressure sensors
  • Cut and clecoed the heater shroud input tube onto the heater shroud.

I mounted the battery backup under the shelf so that it’s a little easier to get to. The batteries will need to be changed sometime plus there is a fuse that may need to get replaced if is every blows.

The GEA24 is mounted and I also finished up all the wiring to it (not shown in the photo). I made up a small circuit board that has the diodes and resistors that’s needed for the RPM and oil pressure sensor to interface to the GEA24.

This is a very simple pre-done board that I bought from Sparkfun. The board internally has every set of 3 holes connected so you can lay things out to connect to each other without having to run wires. I used the captive screw terminals so I can connect the RPM wires from the TCU on the one set and the signal wire from the oil pressure sensor on the other set (only one of the two is used). To install it I connected the wires to the captive screws and then just wrapped it with some silicone tape and the tie wrapped it to the J243 connector of the GEA24.

GEA24 and Other Wiring

Time: 8hrs

Over the past few days I’ve been doing some wiring while waiting for the parts from TAF and the hoses from Aircraft Specialty. I’m not done with the work I wanted to get done, but I figured I should post the progress since I haven’t posted in a while. I’ll be using the Garmin G3X so the Engine Management System module that is used with that is the GEA24. There is also an older GSU73 EMS that incorporates the ADHARS and a few other components, but the GEA24 seems to be more of the standard now. The wiring of the GEA24 is fairly straight forward, there are a few instances where some extra electronic components are needed. One connection is the Tach (RPM) input from the Rotax trigger coil and also a resistor need for the oil pressure sensors. There is a Garmin kit #011-02348-00 which contains all fo the these miscellaneous diodes and resistors, but it’s a bit hard to find. I did manage to find it on a site called Gardner Lowe Aviation Services so I’m hoping that works out. The kit also comes with the more encompassing Garmin Rotax Sensor kit, but I didn’t buy that since there were components that I wasn’t going to use from that. If all else fails I’ll buy the components separately.

One point of confusion for me was how to wire up the temperature sensors. Rotax provides the oil and cylinder/water temperature sensors (I added the airbox sensor). These are essentially VDO resistive sensors, they have one wired connection and ground themselves to the engine block. I did a little looking and found that the RV12 which uses the Rotax 912 uses a single conductor out to the sensor. I saw at TAF (and confirmed with a few other builders) that they ran a 2 conductor shielded wire out to each sensor. One conductor connects to the sensor and the other to the engine block close to the sensor. I also asked Garmin and they said that the “LO” pin needs to be grounded, however from the RV G3X wiring diagram this isn’t the case and even if the pin needs to be grounded grounding back to the main ground block should be sufficient since the main ground block also connect to the engine block. Now having multiple grounds out to each sensor does provide some redundancy which is nice, but it could also cause some potential ground loops. In the end I decided to follow the RV way and not ground the “LO” pin at all. If the sensors don’t work I can pretty easily run a ground from the 4 “LO” pins (one for each temp sensor) to the main ground block.

I also did quite a bit of organizing and clean up of the other fuselage cable runs. I needed to cut back the cable sleeves and permanently label the wire bundles. Grounds will run back to the main ground block on the inside of the firewall. I installed some wire tie brackets to run cables along the top rib. Additionally I made some brackets that I attached to the support which I used to bot a few adel clamps onto so that the cable can run up and out of the center console area without fear of having it rub on any metal edges.

Edge grommet installed for all the sensor wires to pass through the top rib. The GEA24 will be mounted to the right of the hole. I left a bit of wire as a service loop so it’s easier to work on the connectors.

The GEA24 connectors mostly wired up. I’ll need to finish up the RPM and oil pressure wiring once I get the Garmin kit.

I didn’t realize how blurry this photo was until now. I’ll have to retake it tomorrow. This photo has the GEA24 connectors pretty much done with the inexpensive Chinese knock-off GEA24 installed :-). I cut back the wire sleeves on all the cables and labeled them. The grounds are run through the center hole in the top rib (Need to install edge grommet). Now that the cable is all organized it doesn’t feel so daunting of a task to wire everything up.  I’ll need to purchase a few of the avionics that get mounted on the top rib now (GEA24, TCW battery backup, and the VPX)

Control Stick Grips Engraving

I got my control stick grips back from Midwest Sky Sports with the engraving done on them. I’m really happy with the way they came and and am thankful to Steve O’Connor from Midwest Sky Sports for getting it done and also for Kevin from Tosten Manufacturing. There’s a special plastic that is needed in order to do the engraving and I had already purchased my grips with the soft touch plastic about 6 months ago. Steve contacted Kevin and Kevin told be to just send the grips in and he swapped the plastic out for free. He also sent them over to Steve so he could do the engraving. So not only does Tosten make some cool control stick grips but their support is great as well. I like to support companies (and people) that are helpful and willing to work with you so if you’re thinking about which grips to buy definitely check them out first at www.tostenmanufacturing.com. Steve is also very active with the other Sling builders and has some good experience with the Slings. I believe TAF at Torrance has been working with them to build some panels so they’re a good resource to hit up if you need some custom wiring done or engraving done.

A few photos of the grips. These are the MS style grips and I added the side thumb switch which will be my AP Disconnect. The trigger is PTT. I’m not using the left/right hat switch and the small front button by the trigger. Steve recommended using the left/right hat switch for frequency swap who seemed like a good idea, but I don’t think I’d every use it and I’d have to do more wiring so I decided not to do that.

I also received my prop extension and spinner flange from Airmaster so I should be able to fit the cowling soon. I want to finish up the charge system wiring which I’m almost done with, just waiting on some terminal ends for the 6 AWG wire. Since I haven’t bough the propeller yet Jean worked with Airmaster to get me what I needed to fit the cowl (Thanks Jean).


Rear Seat Back Stops and ELT Antenna

Time: 2.75hrs (includes .75 avionics time)

Today I did some work on the interior section behind the rear seat. Prior to installing the rear seat stops I riveted and covered the area with carpet. I also had to drill a few missing holes in the rib. For the ELT antenna I put in a few M3 rivets so that I could remove the antenna if I decide to move it to a new place. Unfortunately the only better place I can think of would be just in front of the vertical stabilizer inside the fiberglass and running cable back there will be quite involved. I’ll try this out and if it doesn’t work then I’ll have to move it. I also made a mistake and mounted the antenna a bit too low on the rib. I forgot that the BNC connector would add about an inch to the length of the cable. It would have worked but it was a bit too close to the luggage support and I didn’t want the connector to vibrate and have issues so I moved the antenna up about an inch and installed 2 more rivnuts. I covered the other rivnuts with carpet. I also drilled out the top line of holes in the side inner skins (the holes that go into the fiberglass of the canopy).

The ELT mounted using 2 M3 rivnuts onto the rib. Covered the area with carpet and installed the seat stop. I also drilled a hole in the luggage support and installed a grommet for the antenna coax cable and crimped on the BNC end. I put some large diameter wire sheathing over the BNC connector and cable, just thought it looked a little nicer. I still want to install a few clips to hold the antenna on the rib.

Carpet installed and rear seat back stop installed as well. I will have to check how well the latch on the rear seat works. I saw that Peter C. added extensions on the seat stops because they barely reached the latch. I may need to do the same.