In modern glass-cockpit aircraft like the Cirrus SR20/22 with the Perspective system, the S-TEC 55X interfaces are complex and must be handled with care:
The pitch and roll servos are the mechanical "muscles" of the autopilot, moving the aircraft's control surfaces.
: External switches for AP Disconnect, CWS (Control Wheel Steering), and Trim Master. 🔌 Wiring & Pinout Essentials
Provides automatic pitch trim adjustments to relieve aerodynamic pressure on the primary pitch servo.
: Attach the servo bridle cables to the main flight control cables using the specified cable clamps. S-tec 55x Installation Manual
: The manual dictates the use of calibrated tensiometers, breakout boxes, and specific crimping tools (e.g., Daniels GMT232 or equivalent). System Components and Architecture
The internal slip clutches of the servos must be tested using a calibrated torque wrench.
Installing servos in the tail and wings shifts the aircraft's center of gravity (CG). The installation manual provides precise weights for each component. You must calculate a new Weight and Balance report before the aircraft is cleared for flight. 3. Mechanical Installation Procedures
The final step of the installation manual is the flight test protocol, which evaluates system gains and stability in the air. Common Installation Errors and Solutions In modern glass-cockpit aircraft like the Cirrus SR20/22
If integrating with glass cockpits (e.g., Garmin GNS 430 or Sandel HSI), refer to the System 55X Troubleshooting Guide for correct ARINC 429 configuration and internal settings. AP-S-TEC-Fifty-Five-X-Manual.pdf - Pacific Flying Club
The S-TEC System Fifty Five X is a two-axis, digital autopilot system widely used in the retrofit market for general aviation aircraft ranging from single-engine pistons to light twins. Unlike older analog systems, the 55X utilizes a digital computer to process attitude and heading information, offering features such as altitude hold, vertical speed selection, GPS steering (GPSS), and precision approach coupling.
Install the roll servo and pitch servo using the appropriate STC bracket kits.
Includes the absolute pressure transducer for altitude hold and optional glide slope couplers. 2. Pre-Installation and STC Compliance : Attach the servo bridle cables to the
Once installed, the system must undergo specific bench and flight line tests: S-TEC 55x installation guide (wiring) - BeechTalk.com
The primary resource for installing the is the Installation Service Instruction (SI-22-01) . Note that in the aviation industry, a complete installation typically requires a Supplemental Type Certificate (STC) specific to your aircraft's serial number, which S-TEC provides alongside the official documentation upon purchase. Key Installation Documentation
The final step of the installation manual is the tracking and performance flight test. In-Flight Calibration