Trio Auto Pilot's


One of my favorite features on my RV-6A was the Trio Avionics EZ Pilot autopilot for the roll axis. It is a tremendously capable unit and has never failed me driving around in the soup. If you have ever flown behind a Navaid, or an S-tec, then you know that capturing a course line can be sporty and down right anoying. With the Trio and its very smart chipset, it will drop you on a course line from ANY intercept with no overshoot. It is truly amazing and it is an absolute requirement for any real IFR work in an RV.

Recently Trio has been developing their Altitude Hold unit and I have one of the very first units for beta testing. There are 4 main components to the installation

1. The pitch servo which installs like any other

2. The computer with holds the brains including interconnect between devices

3. The button. This is an LCD button that serves as a multi function device.

4. The knob. This is a knob that's turns with clicks right and left as well as has a momentary push in.

Out of the box I was very impressed with the quality of all the components. very nice machine work and attention to detail of all the items you will need for installation less the wire. The will probably have a wire harness at some point and is one of my recommendations to them. You will need 22ga 4 conductor shielded aircraft wire for most of the wiring.

The pitch servo on the RV-8 can be located just aft of the rear baggage and foreward of the bell crank for the elevator. I used .040 aluminum angle and fabricated pieces to go between the support rails for the bell crank. 8/32 bolts to hold em in place. I had these scrap pieces laying around. You will need to shim as required with washers.

Next I fabricated the pushrod from the supplied parts to attach to the bell crank. I followed the installations very carefully. The absolute most important item is to ensure the full travel of the elevator is not giving you full travel on the servo. You do not want the servo end stops being the elevator stop at any time. I did have to remove the servo bell crank and flip it 180deg to point upward. Four screws no big deal. Measure twice and cut once, the pushrod was ready in about 10 minutes. the supplied bearings, tube, and machined parts including rivets were of high quality. Oh and don't forget to put the big washer on the outside of the bearing so that if the bearing were to ever fail, at least it wont flap around and jam up your elevator. Lastly I wired her up with the supplied Molex connector and pins and buttoned her up. I had already run my wires here during the building process in preparation of the servo and that made it easier for me. You will have to pull a single 22ga four conductor shielded wire to the servo location.

Next was selecting a suitable location for the computer. Since it needs to be teed into the static system, and wired to the button and turn knob, then up behind the instrument panel was the logical choice. The computer is stamped with "Top" and "Right" for proper orientation. I fastened it to my Trio EZ Pilot control head for no other reason than its the only space I had left.


Next was to drill a round hole for the knob. That was easy.


Lastly was to cut a hole for the square button. Putting a square hole in an RV panel is probably the most difficult task of the project to get right. First I made a template of the cut out from scrap. Next I Put the template up to the panel and marked its location. Be careful cause there is a top and botton to the display. Next I used an 1/8" drill and drilled the four corners of the square. Next I used a stepper but to drill or the center. And finally a flat file to file everything to the corner holes and Im done.


The final step in the process is wiring up the db pins. I have found these to be very reliable in my RV-6A with the only drawback being getting the wires soldered in there in the first place. You will need a pointy soldering iron and some solder with rosin core. Follow the wiring diagram to pre-wire the computer to the knob and button first, outside the plane while you have access. Finally put the harness you just made with the supplied connectors in the plane and wire up the audio, power, & ground. Be mindful that there are upgrades coming for future enhancements for trim control so you may want to go ahead and do you wire pulls for that now. Tee off your static somewhere and your ready for ground tests. B