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

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

Fuselage Wiring

Today I did a lot of wire organizing in the forward section of the fuselage, under the panel. All of the cables routed from the aft fuselage and under the seats funnels into the center section and routes on the floor up to the panel.

Once I organized the rats nest of wires I ended up with two nice bundles. These include the two trim motors, flap motor, ADSB, transponder, ELT, and ADHARS unit. These will be wired to the different serial and power connectors under the panel.

On the right side of the fuse I’ve separated out the radio antenna wire so that I reduce interference as much as possible. This will be behind there side panel from my interior, so it won’t be seen. The RG400 coax wire has a minimum bend radius of 1in, which I am well above in all these bends.

On the left side of the fuse I’ve bundled my two autopilot harnesses. These are separated out from the power wires and autopilot disconnect which will route directly to the pilots stick. The Dynon autopilot harnesses are the standard SkyView Net 9 conductor harnesses except for power. So the only wires needed are the paired data wires.

Here are the Dsub15 connectors for the GPS, ADSB, and Transponder. The red wire for the ADSB and Transponder are left off the connector in order to connect to the VPX. The GPS is powered by the SkyView screens, so it’s fully pinned into the connector.

There are 5 components that use serial connections. In order to connect all the serial to both the PFD and MFD screens, I made a serial bus board that has 7 connections. These are all hooked up in parallel on each pin. When I connect all the connections to the board, each screen will be hooked up to each component properly. I’ve done the pins so that each Rx and Tx from the screens are assigned properly.

Fuselage Wiring

VPX Installation

Yesterday I spent most of the day at the hangar cleaning up and working on the installation of the VPX mounting brackets.


I started with the rough position of the mounting brackets under the sub panel ribs. This will be the final position of the VPX under the panel.

Each corner needed a nut plate installed, so I match drilled the brackets to the ribs, and then lined up the nuplates and clamped them in place.

I then drilled all the nut plates, deburred, dimpled, and riveted the nut plates to the sub panel ribs.

Here’s the close up of one of the nut plates riveted in place with the angle bracket loosely held in place with a mounting screw.

During the day, a friend of mine visited the hangar to check out the project. He took this awesome picture, thanks for hanging out (and helping) Andrew!

It was fun to chat about the project, and airplanes in general. I always enjoy sharing my love for aviation with other people.

Later in the day, I received a nice shipment from Dynon! My autopilot panel, and my comm radio were delivered! These are some of the final components in my avionics package. The remaining component is the second HDX screen.

AP panel

These buttons are very satisfying to push! I’m looking forward to installing this in the plane soon!

VPX Installation

VPX Wiring

Today I spent a few hours working on the main power harnesses. Since I’m using the Vertical Power VPX, all the power wires connect to a central distribution point including the panel switches. It’s all very straightforward once you have the pins all planned out.

Vertical power VPX

Here’s the VPX mounted under the panel (it’s all upside down) so that I could reference the two D25 connectors for J1 and J2. The J8 connector, as well as the J10 and J12 connectit’s on the other side are used for the larger power distribution, whereas the J1 and J2 connectors are for switches (connects to ground), flap position sensor, and serial Tx/Rx for communicating with the EFIS.

J12 connector

Here’s the backside of the J12 connector. Not all the pins are used, and they are left empty. I used my heat shrink tubing labeler to mark each wire for each of the five connectors.

All the wiring harnesses completed

Here are all five of the main power harnesses completed. The final wire runs will need to be done in the plane, but that won’t take too much effort once I rivet in the sub-panel and can start installing components. There are 50 wires here that each are labeled with their respective pins and connectors in order to easily route and attach to the correct components. I genuinely enjoyed this work and look forward to more of the avionics installation and wiring!

VPX Wiring

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

Roll Trim System

This weekend I spent a few hours working on the roll trim system. I’m using the Ray Allen trim system from Vans, so everything is nicely packaged together into its own subsystem.

Modified trim bushing block

I started out by modifying the plastic block that holds the pivot arm. This needed two holes drilled through it foe the AN3 bolts that hold it to the aluminum plate. I also botched the larger counter bored hole to allow access to the cotter pin that holds the pivot arm in place.

Mounting plate drilled

I then trimmed and match drilled the mounting plate to the seat pan holes. This allowed for a perfect fit. Once I drilled the two holes on the left, I temporarily installed it to drill the two holes on the right to the floor ribs.

Original hole and new hole in ribs

Here you can see the original hole where the nut plate was. I removed the nut plate and then used the center hole to mount the plate in order to drill the bottom hole. This was done on both sides of the center channel.

Cutting the pivot arm to the right length

I then cut the pivot arm tube to the right length so it can sit in the block and then be mounted to the metal plate. I cut off about an inch of tube. Once I did that I drilled a 1/16th hole for the cotter pin.

Mounting plate completed

After drilling the block to the mounting plate, I dimpled, and mounted the nut plates to the mounting plate. I will complete this plate by priming it before final installation.

Pivot arm installed into block

I then installed the pivot arm into the plastic block, and then installed the washer and cotter pin to hold it all together.

Test fitting the assembly

I then test fit the assembly by installing the bottom two screws. The top two are where the floor is held on to the ribs. The pivot arm needed to be adjusted to not rub on the control rod.

In the bottom left is the servo block. I need to drill that to the floor rib for final installation as well.

The final thing to do next time is to finishing the assembly with the control stick springs and cleaning up the assembly with some final adjustments.

Roll Trim System

Wing tank brackets

This weekend I spent a few hours working on the plane. I wanted to get some specific things done in order to make a little progress towards fitting the wings.

Wing fuel tank attach bracket

I spent the day installing the fuel tank attach bracket to the outside of the fuselage. This required fabricating the internal support bracket and spacers. It took a little longer than I though, but got it done.

After taking these pictures, I buffer and then primed the brackets. These are steel so they are very susceptible to corrosion. Now that these are installed. I can prep to mount and test fit the wings!

After this I spent an hour or so finishing up the exhaust hangar modification. I didn’t take any pictures, but because I’m using the Vetterman 4 pipe exhaust and the heat muff, the standard Vans exhaust hanger can’t be used on that side. So I fabricated a support bar that shifts the hangar mounting point outboard of the heat muff. I finished it by drilling the bolt hole for the mount and attaching it with all metal lock nuts.

I also removed the bolts for the exhaust attaching it to the engine in preparation for riveting the firewall to the bottom skin where the exhaust exits the cowl. This isn’t accessible when the exhaust it attached to the engine.

Wing tank brackets

Fuselage gussets

Today I spent a couple hours putting the forward fuselage gussets in place. They are unique to the -7 vs the -7A. The tri-gear plane rear landing gear are mounted just forward of the center section. Since the -7 is a tail trager, there is a gap here that need to be reinforced using these gussets. They are attached to the sides of the fuselage with 5 bolts that need to be match drilled. The gussets also line up with the bottom wing attach bolts.

I lined everything up and then drilled the holes to #40 and then enlarged for the AN3 bolts. I prepped and primed these and then attached them to the fuselage. The whole interior will be painted with my interior paint, but it’s good to prime all the parts especially mating surfaces.

I also sent a bit of time working on the panel attachment brackets. Since I’m using twin Skyview HDC screens, I need to move the Vans panel supports inboard. This requires making some custom brackets to attach the panel to the sub panel. I received a shipment of L stock from vans that worked perfectly for this.

I decided to wrap up the center section bolts that are used for the tricycle gear. In the tail dragged version the bolts need to be put into the center section.

The bottom bolts were difficult to reach but everything is now in place and torqued.

I also placed the remaining two cover supports on the sides of the fuselage, forward of the center section.

Next up is to wrap up the exhaust hangar modification. And to drill the wing fuel attachment bracket to the sides of the fuselage.

Fuselage gussets