Chapter 22.4 Electrical: Phase I Testing
A couple of years after doing the electrical system, I entered Phase I flight testing I had a few issues that I want to illuminate in this page for others who might have similar configurations or observations. The major relevant equipment references are that I'm running Dynon Skyview on an HDX1100 with a VP-X Sport solid state electrical distribution box (for most circuits) and the UL Power 520is engine. I will note that aerodynamically the plane flew great right from the first flight, so addressing these issues did not feel so daunting. Though I'd provisioned for ADSB-IN in the electrical system, I had not yet installed an ADSB-IN box from Dynon. I was already ADSB-Out compliant with the Dynon SV-261 S-Mode XPNDR with SV-GPS-2020. I've chosen for now to go with an iPad/Foreflight/Scout/DualGPS for my Navigation/ADSB-In display, since I'd been using this setup in rental planes before the Cozy was flight ready. See bottom of this page for link to other Phase I testing information.
Alternator Fault on VP-X Display in Dynon HDX:
This fault is clearly apparent as the throttle is increased (typically on the runway...) and is quite disturbing, as you get a Dynon audible alert "engine monitor" with red warning message targeting the VP-X. If you display the VP-X screen it shows the Alternator red at the top and the VP-X top center icon red as "Fault". All the other circuits may look fine (mine did). Because it had been a couple of years since I'd configured the VP-X in my garage (before I had the engine) it took me a while to find the issue. Another impediment was that the "fault" would clear on it's own in a few seconds, and it was a while before I could pull up the VP-X view in time to see it (I was often busy doing something like taxiing or flying the plane...). I talked first to Vertical Power and they knew what this was. As we talked and I realized that this was a regular alternator field winding monitoring system, and the UL engines have a permanent magnet alternator, it was clear that this VP-X functionality needed to be disabled. However, further conversation with Dynon highlighted that there is a bug on their side that prevents it from recognizing the "disabled" alternator field winding circuit. The fix prescribed by Dynon was to "enable" the field winding circuit in the VP-X Configurator, and set the current allowable to 1 Amp, and turn off current fault monitoring. Dynon will monitor it but would not do anything. Since there is nothing actually connected to the VP-X for this circuit, no current or voltage will actually exist on it. Once these changes were made this fault condition went away on the HDX. |
USB Power: (not an issue: an improvement)
As I started to fly away from my home aiprort I wanted to incorporate the iPad/Foreflight that I'd used in my Cessna flying so I designed and 3D printed a bracket to hold it at an angle on the copilot side of the IP. My configuration uses the inexpensive Scout ADSB-IN/Weather receiver, and an independent Wifi GPS puck from Dual. The Scout requires USB based power and the GPS can also take USB power like the iPad but has a battery too. I decided that I'd want USB power available up front in general for phone's etc so I added a VP-X circuit for USB power that was ON when ever the VP-X is on. I got a car USB power accessory and wired it to this new circuit and positioned some of it's outlets on the pilot side and some on the co-pilot side. I then needed USB cords of an appropriate length to plug in all the components described above. I'd used a USB battery to run the Scout previously, but decided NOT to try and integrate the battery at this time because it required opening USB cables to enable insertion of a switch that would prevent the battery being drained when the circuit is not active (IF the Scout was not unplugged). I didn't want this complexity yet. I added a little sticker on the longeron where I'm looking when I close the canopy to remind me to turn-off the Dual GPS. This prevents it running it's internal battery down when the USB power (Master Switch) is off. |
Warning Lights Update:
I went through a lot of iterations with the programming and testing on the Warning Lights because I evolved my thinking as I started to prepare to fly the Cozy. This was a major advantage of using the Arduino, as this really involved mainly programming changes vs electrical wiring changes.
I'd struggled some with getting the grounds right (you can't share the grounds from the microswitches going into the Arduino. I also evolved my thinking after getting 12V from an alternative method (externally powering a micro switch) which was a terrible idea. I replaced the Arduino, but the system never behaved properly AND reliably after that. After much wire inspection and trials and program adjustments, AND starting to fly my Phase I, I realized that I wanted simplicity and reliability much more than extensive checking of things like the fuel pumps and the ECU switch status. These were so obvious, I didn't need a warning light to help me with them. I simplified my scheme and resolved to build a whole new Arduino system with this simplified wiring in the same box to achieve the reliability I needed. Here's the logic I'm implementing:
Canopy LED: ON if canopy not latched and throttle >30%
Brake LED: ON if brake NOT retracted and throttle >30%
Gear LED: ON if Gear not all the way down AND throttle <20% AND (assuming I can get it to work) AGL < 400 ft
I'll report more on this when I have this updated system back in place and working.
Dynon SV Audible Warning "Check Gear"
I ALSO activated the Dynon audible warning functionality to give me an audible warning when flying below a pre-set Airspeed with nosegear UP. The audible is "CHECK GEAR" and I have it set to 90 kts. I did this following the Dynon instructions for Contact sensors with a microswitch closing with the gear all the way down. Dynon outputs an "Engine Monitor" audible warning on takeoff, when you raise the gear before reaching the Check Gear speed, which happens on every takeoff since I raise the gear after indicating positive rate of climb, but I'm conditioned for it, and can quickly check the Warnings Button, which shows GEAR CONTACT HIGH. I wish the Dynon system was smarter, but I can live with this.
I went through a lot of iterations with the programming and testing on the Warning Lights because I evolved my thinking as I started to prepare to fly the Cozy. This was a major advantage of using the Arduino, as this really involved mainly programming changes vs electrical wiring changes.
I'd struggled some with getting the grounds right (you can't share the grounds from the microswitches going into the Arduino. I also evolved my thinking after getting 12V from an alternative method (externally powering a micro switch) which was a terrible idea. I replaced the Arduino, but the system never behaved properly AND reliably after that. After much wire inspection and trials and program adjustments, AND starting to fly my Phase I, I realized that I wanted simplicity and reliability much more than extensive checking of things like the fuel pumps and the ECU switch status. These were so obvious, I didn't need a warning light to help me with them. I simplified my scheme and resolved to build a whole new Arduino system with this simplified wiring in the same box to achieve the reliability I needed. Here's the logic I'm implementing:
Canopy LED: ON if canopy not latched and throttle >30%
Brake LED: ON if brake NOT retracted and throttle >30%
Gear LED: ON if Gear not all the way down AND throttle <20% AND (assuming I can get it to work) AGL < 400 ft
I'll report more on this when I have this updated system back in place and working.
Dynon SV Audible Warning "Check Gear"
I ALSO activated the Dynon audible warning functionality to give me an audible warning when flying below a pre-set Airspeed with nosegear UP. The audible is "CHECK GEAR" and I have it set to 90 kts. I did this following the Dynon instructions for Contact sensors with a microswitch closing with the gear all the way down. Dynon outputs an "Engine Monitor" audible warning on takeoff, when you raise the gear before reaching the Check Gear speed, which happens on every takeoff since I raise the gear after indicating positive rate of climb, but I'm conditioned for it, and can quickly check the Warnings Button, which shows GEAR CONTACT HIGH. I wish the Dynon system was smarter, but I can live with this.
Go to: Ch 22 Instrument Panel
Go to: Ch 23 Engine
Go to: Ch 27 Ground Testing, First Flight, Phase I testing
Go to: Ch 23 Engine
Go to: Ch 27 Ground Testing, First Flight, Phase I testing