Stick control wiring

With both the left and right panel switches and breakers in, I was finally able to cut down the control sticks, install the stick grips, and start wiring the controls. I previously drilled the control sticks at the hand end so I could wire the controls internal to the stick tubes, but now that things are a little further together, I think that is a bad idea. The problem is not the end near the stick it is the pivot under the seat. The WD-1011 bracket under the seat has a 90 degree enclosed angle in it. I may re-think this later, but in order to get the wire to exit the control stick I would have to put a hole somehwere in the WD-1011 stick base. I remember thinking that I would pull the wire through the bottom of that control base, but now that I have the F-1064 push rods in place with the F-1065 that would be the wire bundle in interference with the physical controls of the plane. That I am not comfortable with.





I am going to keep the wiring on the outside of the control stick. I am using a connector that still fits through the control stick (at least the straight part of it) so if I ever needed to service my control wires it wouldn't be much of a problem. I chose some 7 pin circular connectors from Amphenol (APC1629-ND). The really great thing about these connectors is that they use same High Density pins and sockets that the DB connectors use for most of the other avionics.



The 7 control stick wires fit nicely into the connector, and the connector is actually small enough to fit through the control stick in case you choose to pop a hole in the control stick and route the wire inside of the stick.



The wiring pattern for the control sticks are as follows:

Pin	Stick Wire Color	Switch	Airplane Wire
A	Blue	Trim (Up)	Red (VPX Trim Up)
B	Brown	Button (Black)	Not used
C	Yellow	Trim (Right)	Black (VPX Trim Right)
D	Purple	Trim (Left)	White Black (VPX Trim Left)
E	Red	Button (Red)	White Black (CWS/Autopilot Disconnect)
F	White	Button (PTT)	White Yellow (Pilot) White Brown (Co-Pilot)
G	Green	Trim (Down)	White Red (VPX Trim Down)
H	Black	Ground (common)	Black (GND_ControlStick)

Ignition Breaker wire isolater

I ended up putting 3 mechanical breakers on the co-pilots side console for the ignition coil packs and two ignitions. These circuits are fed from an essential bus sourced by either the aux or main contactors in the rear of the aircraft. Both of the buses are connected to a schottky diode which means that if there is ANY power in the system, it will feed the essential buss.

I opted to not put any of these flight critical items on the VPX. I also opted to keep them out of the AUX fuse block because I wanted them to be in-flight resettable. On my first installation of this setup, I was uncomfortable that now my safety came down to a single yellow ring terminal and a dangling wire. There was no real great way to isolate movement of that cable. After a couple of goes at various circular connectors and adel clamps I came up with the following design:



In this approach I removed all connectors and wired everything direct to the breakers, but isolated movement of the cable with a standoff that I could solidly mount to adel clamps to. Out of the design and into metal it goes.




Probably a little overkill, but why not when you have the tools, the software, and some spare time on the plane for work.


I suppose I have to grab another photo yet of the final install, but here it is for now.

FlyEfii Coil Bracket

If you remember when I got my System32, I struggled with how to mount the 3 coils forward of the firewall. A lot of people had just been using Adel clamps to secure the coil pack to the engine mount. The coils are surprisingly heavy though, and I think far too heavy for adel clamps. At the time, I had found some great bar mounts that I had milled and modified to fit my application. I was really happy with that however when I went to go install the cowl top, they coil pack was sitting too high and touching the cowl top.

With that, my new coil pack design had three goals. 1) securely mount the coil pack to the top bar of the engine mount with ubolts. 2) If possible, get some vibration dampening in the mount 3) Keep the coil packs as low as possible so they did not touch the show planes cowl.

To accomplish these goals, I ended up with a plate that allowed the coil pack to pass through the plate allowing me to put the coil pack at a minimum distance above the actual bar.

I drew this up in Fusion 360.


Then put it on my router table in the basement.



I did cheat and mill this out of plywood twice because I didn't want to destroy the $100 chunk of aluminum. The final product though is shown below.

I secure this to the top bar of the engine mount with three cushioned stainless u-bolts from mcmaster.

I could not get the fourth one because of the intersection of two bars right where I wanted to put a u-bolt.


The final product however was perfect. The coil packs are secured to the plate with 3 AN-4 16 bolts and 3 washers standing them off of the bar by 1/8".

Battery Monitoring

I ended up with two EarthX ETX900-VNT batteries in N5412K. To monitor the batteries, I have a couple of things going on. First off, I have the battery fault ground wire coming all the way up to my panel where there is a red led (79-2977-ND) on my panel right next to my Master and Aux bus switches. In the event that there is a failure with one or both of the batteries, this LED will flash with an error status.




The error codes for the battery are as follows:


The second monitoring system on the batteries is the Garmin G3X with a GEA24. I have the GEA24 configured to display the volts and current for both the MASTER and AUX bus. The Volts 1 and amps fields are fed from the VPX-Pro serial line to display the MASTER status. The AUX volts (volts2) is fed from the GEA24 Aircraft Power 2 line (which is connected to my AUX fuseblock). The AUX amps (amps2) is fed from a shunt I have on my AUX bus near the fuseblock.

The shunt has a 1A fuselink (F2313-ND) on each one of the lines. Hopefully these never blow, but I did install them in a format that allow them to be easily replaced. Yes this photo is taken before securing the wires.




The G3X / GEA24 is configured to have Red,Yellow, Green bands on the engine display page. Since this is a lithium battery, the settings are a little different than a lead acid. By the time a lithium (12v) gets to ~11.5v it is completely drained. The normal resting voltage is 13.3v. So I configured with the following settings:

• Red: 0-11.5v
• Yellow with Alert: 11.5-13.5v (alternator not charging)
• Green: 13.5-14.9v
• Red: 14.9-16.0v

The Main alternator is a AL12-EE70/B while the backup is a FS1-14B. Only one alternator will be live at any given point in time and the switch over between the two is a manual operation via a physical panel switch that controls the VPX ALT1 and ALT2 power pins. The alternators do come together at the firewall pass through, so the alternators only ever feed the MASTER bus. The AUX bus gets charged via the X-Feed contactor (via the MASTER bus). This makes the AMP alert settings a little more complex. 


The AUX bus consists or a battery, contactor, a 6 Ga wire coming forward to the mid-panel where a fuseblock distributes the AUX power to the backup power pins of the essential avionics. The 6 Ga wire is the limiting factor for this bus. Let's be super conservative and say that in our 10ft run we don't want to exceed 30As. I do not have 30As of avionics even hooked up to this... So for the AUX bus I have the following

Red: 0-2A 

Green: 2-20A

Yellow: 20-25A

Red: 25-30A 

The thought here is that we are watching how much power is getting sinked into the system, not the amount of current going into the system (alternator shunt). So if the plane is on, we should have at least 1A going out of the AUX bus (from what I have been watching I have a consistent 2A with the transponder off). Anywhere from 2-20A is normal. 20A is the sum of all the fuses I have in the AUX fuse block,  so if there is more than 20A indicating, then there is a short between the shunt and the fuseblock (6inches).

The MASTER bus Amp reading gets its data directly from the VPX-Pro via the serial line. The VPX page on the G3X has a pretty nice display for each one of the outputs themselves. I chose to set the color bars on the Master Amp gauge relative to what the main alternator can output. This is a little mis-leading. If I am functioning off of my main alternator, then I have 70As to work with. However, if I have switched over to my backup alternator for some reason, then I only have 30A to work with. So I know how much my VPX is outputting, but I did not put shunts on the alternator lines, so I do not know how much current is coming from the alternators.

Red: 0-4A 

Green: 4-60A

Yellow: 60-65A

Red: 65-70A 

I have to look into this a little later to see if there is anything smart I can do with the GEA24 discrete inputs. I do know that if I have switched over to the backup alternator (for other than just testing), that I am already looking at where and how to land. So I am not sure I care to deep dive too much into this case.

VPX-PRO configuration

Don't read this diagram and post as my final electrical configuration, however the diagram at this point is pretty close to my final MAIN Bus configuration. The first realization that you should have if you are looking at this is the number of pins you actually need in a modern avionics package. For the most part, every one of my connectors is fully populated. And this is just one of my busses, I still have another AUX bus in addition to this MAIN bus! Also an Essential bus on top of that!

I have a Z-14 inspired design (which is not depicted in the default VPX planner diagram). This is a two alternator and two battery design (again, not depicted here) that can be connected via a single X-Feed contactor. Both of the outputs of each bus contactor feed a Schottky E-Bus Diode to create an essential bus for my electronic ignition.

The Main alternator is a AL12-EE70/B while the backup is a FS1-14B. Only one alternator will be live at any given point in time and the switch over between the two is a manual operation via a physical panel switch that controls the VPX ALT1 and ALT2 power pins. There are actually two switched inputs into the VPX for ALT1 and ALT2 that are connected to a SPDT on the VPX, but the VPX does also manage the ALT lines to ensure only one alternator can be active at any given point in time.

The VPX is physically located above my left side rudder pedals on a custom bracket that spans the firewall to mid-panel. This turned out to be a great place for the VPX, however I will warn you, think about your connectors with the wires attached when planning where to put your VPX box. With the connectors and wires connected, there is not much room above the rudder pedals.

Trying to avoid single points of failure was the goal in my setup.  I mention my alternator setup because that is one of the first things I struggled with that I was not fully excited about (but the best of the options I came up with). Having two batteries and two alternators is obviously for redundancy however while designing you have to balance redundancy with complexity. If you look at the VPX configuration you will see both ALT1 and ALT2 switches as well as ALT1 and ALT2 Field wires. The actual schematic for a given alternator to be enabled is not straight forward. A ground line comes into the my MASTER/ALTERNATOR switch. When the Master switch is moved to the ALT position, this connects ground to the input of a SPDT Alternator selector switch. This in turn tells the VPX-Pro to enable the alternator that is chosen.

From the pilots perspective this alternator setup is not bad. If the alternator appears to not be charging, flip from ALT1 to ALT2. If the system is still not charging at that point one could look at the MFD VPX configuration page to see if the ALT1 or ALT2 power lines have any current draw, but after that, there is not much you would want to do in the air. There are just too many variables behind the panel. 

The second issue that did not excite me was my coil packs on my electronic ignitions. All three coil packs come to a single point and FlyEFII recommends keeping those three feeds together. The problem with this though is that if you loose a connector on your coil pack line your engine is no longer running. At least with the ignitions themselves there is redundancy. The coil pack is a single point of failure. I ended up really not liking the options I came up with on how to feed power to my ignitions and coil packs. Should I bring them back straight to the battery? Which Battery? Do I split the ignitions between AUX and MASTER? If I split up the ignitions on the busses, and the bus that powers the coil pack goes down, whats the point?

I ended up biting the bullet and putting an essential bus in on top of the 2 alternator 2 battery design. Each power contactor feeds a schottky diode making an essential bus. If either the AUX or the MASTER or both are on, the essential bus will have power. I ran a dedicated line from the rear or the aircraft forward for the essential bus and this ultimately goes to the only three physical breakers I have on the plane. A 15A for the Coil pack and 2 5As for the ignitions.

While again, the decision to add a third bus adds complexity, I feel better about the redundancy in the system for the critical components to keep the engine running.

Speaking of complexity... When I first setup my rear mounted avionics tray I forgot that my AUX and X-FEED contactors are reverse from each other, i.e. they are back to back. My MASTER contactor is in the stock location and feeds both the X-FEED contactor as well as the main power line running up to the starter and VPX. 

 

On the left of this image is the AUX contactor with the right being the X-FEED contactor. When installed into the plane, the top right post of this photo gets a 2GA jumper to the output of the MASTER contactor. The top left post of this photo gets a 2GA jumper to the battery. Do you see the problem?

Avionics Status Update

I don't have much to say here other than we can see the light at the end of the tunnel! I debated early on having the wiring harness made, but I am very glad to have done this one myself. There is a level of understanding of how the bytes are flowing over the lines that one would not get if someone else were to have wired and configured the system. 

Everything in green is now complete with only a couple of additional wires to terminate (colored in orange).

Tanks

I have been putting this off for so long. I think it was really the idea of the tank having a massive leak that made me wait so long before pressure testing. I finally got sick of the tank on the ground always in my way and ran over to Walgreens to grab some balloons. Initially I thought I had some major issues because I started pumping up the tank with a bike hand pump and the balloon inflated but did not expand. I kept on pumping thinking surely there is a big leak somewhere in the tank.

It made sense that after a minute or so of pumping (with one of those really really small emergency bike pumps that you store on your bike frame) that the tank had enough pressure in it to overcome the initial push to expand the balloon. (I bought the cheap balloons). I let this sit all day and sprayed it up a couple of times with some soapy water. I did find a small leak on the outer flange baffle seal, but this was a pretty easy fix because I could access it through the gas cap. It wasn't a large leak, but I did find a handful of very small bubbles after an hour or two.

That has since been patched and this tank is finally on the wing where it belongs.