S-tec 55x Installation Manual Jun 2026

The key to a successful autopilot installation is meticulous planning before you turn a single screw. This phase is critical for safety, regulatory compliance, and airworthiness.

The S-TEC 55x requires analog left-right deviation (DC voltage) from a NAV receiver or GPS. The manual provides interface diagrams for:

Wiring the S-TEC 55X requires meticulous attention to shielding, grounding, and pin-out configurations to prevent Radio Frequency Interference (RFI) and Electromagnetic Interference (EMI). 1. Wiring Harness Specifications Use only (or equivalent) Tefzel wire. S-tec 55x Installation Manual

Installing this autopilot requires compliance with FAA AC 43.13-1B and AC 43.13-2B.

The S-TEC 55X features an extensive wiring harness that interfaces with various cockpit instruments. Primary Power and Grounding The key to a successful autopilot installation is

The unit is designed for standard radio stack mounting. The manual specifies the "keep-out" zones to avoid electromagnetic interference (EMI) from other avionics, like high-power COM radios. Servo Installation This is the most labor-intensive part of the manual.

The control panel is the primary interface between the pilot and the autopilot system. To install the control panel: The manual provides interface diagrams for: Wiring the

The programmer and all servos must share a common, low-resistance airframe ground to prevent ground loops, which introduce electrical noise into the navigation signals. Avionics Interfacing

The 55X features built-in GPSS converter logic. Connect the ARINC 429 transmit lines (A and B) from your GPS navigator (e.g., Garmin GTN or GNS series) directly to the designated pins on the 55X harness.

Many modern GPS units output serial ARINC 429, not analog. The manual includes a note that an external DAC (Digital to Analog Converter) may be required, such as the S-TEC GPSS (GPS Steering) adapter.