The Trio Pro Pilot autopilot is compatible with the roll servo from the Navaid Devices wing leveler. But, Trio does not provide any instructions on how to do the wiring. The Trio servo is a development of the Navaid servo, but the Trio servo has some digital brains in it, and the Navaid servo is completely analog. The Trio servo has one more wire going to it than the Navaid servo does. The wire colours on the two servos are similar - red, green and black for the Navaid servo, and red, green, black and white for the Trio servo.

I sent an e-mail to Trio asking for info on how the Navaid servo connected to the Pro Pilot control head. One of the company owners responded, and I wired it as he told me. But, it didn't work. The servo would engage, but it wouldn't drive to neutral nor would it follow left/right commands from the control head. I phone Trio, and spoke with one of their technicians. He diagnosed the problem very quickly, and it turned out that I needed to move one of the wires to a different pin on the control head. Once I did that it worked perfectly.

For the record, the Navaid servo is connected to the Trio Pro Pilot control head as follows:

    Navaid red wire   <--> Trio pin 1
    Navaid green wire <--> Trio pin 2
    Navaid black wire <--> Trio pin 4
    Ground            <--> Trio pin 5

    Note: If shielded wire was used for 
          the Navaid, connect pin 5 to 
          the shield instead of ground.

You can better see all the details in the pdf version of my Trio Autopilot wiring diagram.