More Avionics Wiring

Today I spent a solid chunk of time routing wires. Making wiring harnesses has been one of my the more satisfying parts of the project so far.

Firewall forward

I started by organizing the firewall forward sensor wires. This bundle contains everything from engine temps, to oil and fuel pressure and the ignition harnesses. These are now secured to the engine mount and won’t be able to move.

On the other side of the firewall I’ve secured everything and routed a portion of the harness down the left side of the fuselage in order to route the wires to proper area.

Center tunnel main harness bundle

This is the center section between the pilot and passenger seats. The main harness here is routed up to the vertical power above for all the power distribution. Other parts of this include all the serial connections, and the electric pitch and roll trim motors.

Here’s another look at all the wires and how they’re routed (Ignore the tie wraps and scraps). The harness splits to allow for the left and right lighting wires to route to the correct wing. I’ve isolated all power wires from my radio wires so that there will be no interference.

Serial Hub

This is my serial hub, it had ports for the primary and multifunction flight displays (empty slots) and the five serial avionics. The ADSB, transponder, Vertical Power, GPS and ELT (black box) all communicate via serial. This hub allows all the components to connect to the two main flight displays in parallel for each of the five serial ports. Once I’m down with all the routing of the wires this will be mounted to the sub-panel permanently.

Fuel pump and selector valve

Once I finished with the wiring I wanted to test fit my fuel pump and selector valve. I have custom fuel hoses from TS Flightlines, so I had to modify the brackets to allow the hoses to fit (you can see the cut bracket on the left below the wires). Once I mount the wings, the two fuel hoses will attach to the fuel tanks.

More Avionics Wiring

Ignition Harnesses

Tonight I spent a few hours making my ignition harnesses. My engine uses twin P-Mag ignitions, so I had to make two identical harness.

I started by removing the connectors on the ignitions so I can attach the wires. The connectors use a screw-clamp style connection.

Right ignition

Here you can see the connector attached to the ignition with the wires attached. This is a six pin connector with Ground, ignition kill, power, and RPM out. There are two additional pins that can be shorted in order to change the default timing of the ignition.

Left ignition

The left ignition connector is on the bottom of the ignition and is a bit more challenging to get to, but I managed.

Completed harnesses

Here are the bundles completed. Looking forward to the day I get to start it up!

Ignition Harnesses

Engine Controls Bracket

Yesterday I spent a few hours making the engine controls bracket. The bracket that comes in the kit is flimsy 0.032 aluminum sheet that is bent so it can attach to the bottom of the panel. I knew I wanted to use something different than the stock bracket, so I made one.

Here you can see the completed bracket. It’s made from 1/4” aluminum angle. It’s very hefty. The three holes are for the throttle, prop and mixture control. The two larger holes have relief cuts made on the back of the angle to allow for the nuts to hold the controls onto the bracket.

I then lined the bracket up with the control panel, and drilled matching mounting holes. I then added some nut plates to the panel so that this can easily be mounted flush to the bottom of the panel. Now it just needs some priming and painting and the bracket is done.

Engine Controls Bracket

VPX Wiring #2

Today I continued with my wiring extravaganza. I didn’t get any new pictures, but I started by beeping out the ELT DIN connector. I originally made the harness a few years ago, and forgot to write down the wire designations. I tested the connector and verified with the specs provided with the ELT and then made the DSub15 connector for the serial bus. The ELT just has serial Rx, power and ground.

Here’s the DIN connector that plugs into the ELT. The tail sticking out is to test the Rx signal. It will eventually be tucked away.

VPX J10 & J12

Here are two of the main power connectors from the VPX. I connected these and began to separate out the bundles by where the wires needed to route.

VPX J1, J2, J8

On the other side of the VPX are the two D25 connectors J1 and J2. These are for some lower power items, like flap position sensor and interior lights, as well as the VPX serial connection. The J2 connector is for all the switches. These will go directly to the panel switches, which will be connected to ground on the other side.

Bundled by function and aircraft location

These bundles are such that each group will go to the same general area of the plane. The lighting harness for example is split into two half way down in order to go to the left and right, for each wingtip. Others are for powering the aft components such as the ADSB, transponder, and autopilot servos.

Switch bundle and serial bundle

This side contains the switch bundle, which heads off to the right side of the image from my hand, and the other bundles are for the flap position sensor, and the serial connection.

EMS and other wires

Here’s a wider shot showing the EMS in it’s mounting location. Once the plane is built this area will only be accessible by laying under the panel and accessing it from below.

The last thing I did was to drill the copilot’s control stick for the quick release pin.

This pin allows the copilots stick to be removed in case the passenger wants a more comfortable ride. There will be two wires coming out of here for the copilots PTT for the radio. It will be fitted with a connector in order to make the system removable.

VPX Wiring #2

EMS wiring

This weekend I spent time working on the main EMS wiring harness. It includes everything for engine monitoring including oil pressure, temperature, fuel flow, fuel pressure, manifold pressure, rpm, etc. It’s quiet extensive.

I started by reviewing my wiring diagram that I made, and reviewed the pin out of the EMS D37 connector.

EMS box and connectors

I then opened up the main harness that is included in the skyview EMS in order to identify every pin.

Top half of the connector

I used my multimeter to check each wire and then I used that to label each one according to the function.

EMS temporarily installed

Here’s the EMS and the main harness (silver) plugged in. As you can see in this picture, the wires are labeled and then separated out into the appropriate pairings (e.g. oil pressure power, ground and signal). Then I began to wire the engine sensors and measure the wiring runs.

Firewall pass-through for main harness

Here you can see the main EMS harness come through for all the firewall forward components. Mounted to the top of the firewall is the sensor manifold, which includes oil pressure, fuel pressure, and manifold pressure.

Sensor manifold closeup

Here’s the oil and fuel pressure sensors mounted to the firewall. These are wired into the main harness and share their 5v source on the same pin (pin18) of the EMS. It’s a common source for low power components and is shared between several other sensors.

Oil temperature sensor

Here’s a close up of the oil temp sensor wired to the harness.

Manifold pressure sensor

Here’s the manifold pressure sensor. It has a tube that’s connected to a T in order to share a manifold pressure source with the ignition system. E-Mag ignitions also need to know the pressure of the intake in order to adjust timing of the spark.

Continuing the work is a bit slow, but it’s getting there. Lots left to do.

EMS wiring

Vertical Power PPS

This weekend I had a few hours to work on the plane. It’s been a couple months since I’ve spent a good chunk of time on it.

I decided to take off the old conventional master and starter contractors. I’ve decided to go with Vertical Power Primary Power System. This is a single unit that replaces the contractors, as well as current shunt and fuses. I’m also using the Vertical Power Pro solid state VPX. These two will work really well together.

Vertical Power PPS

For easiest access I mounted this on the edge of the firewall near the battery as far away from the exhaust as possible. Every bolt and post is accessible. I also crimped on the ring terminals for the alternator and for the starter once I had this mounted.

I also wired up the J1 harness that includes all the inputs for the master switch, battery and alternator current sense and fault indicators. This will all feed into my EFIS and be displayed on the engine monitoring page.

Vertical Power PPS

Heat Muff, Exhaust, and Fuel Tubes

Today I spent a few hours working on the exhaust hangars, heater and the fuel lines.

It’s been on my to-do list for a long long time, but I finally marked and drilled the hole in the firewall for the fuel line.

I then test fitted the fuel line between the pump and firewall fitting. I had to fabricate a new tube in order to fit the position I drilled the hole. In hindsight I should have drilled it about one inch to the left of this, in order to provide more room for the heater scat tubing on the other side, however it should be fine.

The forward tunnel cover will go over this portion of the tubing as well as the wiring harness.

I then worked on the hangars for the exhaust as well as heat muff.

Here you can see the hangars before I installed the heat muff. The left hangar here will need to be modified to account for it.

I didn’t get any pictures during the install, but here is the heater installed with the tubing. I will need to add some support to prevent chaffing of the tubes on the engine mount.

I will also need to add some support for the fuel tubing here to prevent rubbing on the tube. It shouldn’t be too difficult to keep these two separated.

I will need to fabricate a support bar to extend the exhaust mount a bit wider in order to attach the hangar in order to avoid the scat tube.

Heat Muff, Exhaust, and Fuel Tubes

Engine work

Today I spent a few hours cleaning the shop and installing some fittings on the engine. My goal is to hang the engine next weekend. 

I started by rotating the prop governor and installed the cable bracket. 

I cut the safety wire on the six screws holding the governor so that I could rotate the lever arm. I then installed the cable bracket in white and reinstalled the screws and re-safety wired them. 

I needed to install the oil cooler fittings, but that requires removing the right p-mag. Once off I could easily screw the fitting in. 

This is the fitting installed and with tape over it to keep moisture out. You can see how tight it is to get a wrench on there. 

The other oil fitting is much easier. 

The fitting (with tape over it) is right above the left p-mag and just under the oil breather tube (with the red cap). 

I also installed the fuel pump outlet and fitting for the fuel pressure. 

Fuel will come out the bottom port and go to the fuel servo near the front of the engine. 

I also installed the oil pressure fitting


And the manifold pressure fitting from the number 3 cylinder. 

You can see it here wrapped in tape just above the oil return line. 

I finally installed the fuel overflow fitting to the fuel pump. 

There are a few more things to install, but that can be done after the engine is hung. There are a few more holes I need to drill in the firewall for cables and wires, but that’s no more than an hour of work, and I’m hoping to get it done some time this week. 

Engine work