have an S-tec 55 autopilot, and would like to install GPSS. Has anyone done this install, and can shed some light. Was the install straight forward, and did it work OK after instalation?

Mark,

 

I installed a GPSS unit between a Garmin 430 and an S-Tec 50.  Remember that the GPSS is first going to convert ARINC 429 Steering Commands into Directional Gyro (DG) or HSI "turn" information for use by the auto pilot (AP),  Its' second function is to act as a switch that either directs the DG or HSI signals or the ARINC 429 converted signals to the AP.  For me, the hardest part was to find a spot near the AP to mount the GPSS unit. The unit requires power, two wires for the ARINC 429 data, a few wires for the DG turn data, all connected thru a D-Sub plug. If you have done similar wiring before it should be a snap.