S-tec 55x Installation Manual

Modern installations often include the GPSS converter module. This allows the autopilot to fly "Great Circle" routes defined by the GPS, providing smoother transitions and turn anticipation than standard VOR deviation tracking.

The most critical section of the Installation Manual concerns the mechanical connection to the aircraft flight controls.

Following the installation manual precisely is critical for several reasons:

In summary, the "S-tec 55x Installation Manual" is a crucial document for ensuring the safe and effective installation of the S-tec 55X autopilot system in an aircraft. It provides detailed instructions and guidelines that must be carefully followed to ensure proper operation, safety, and compliance with aviation regulations.

An installation manual for the S-TEC System 55X contains critical technical data, wiring specifications, and certification requirements. 📋 Installation Prerequisites

STC Requirement: Installation must comply with the Supplemental Type Certificate (STC) specific to your aircraft's serial number. S-tec 55x Installation Manual

Authorized Personnel: Must be installed by an FAA-certified avionics technician or equivalent authority.

Turn Coordinator: This system is rate-based and requires a compatible S-TEC turn coordinator to function as the primary sensor. 🛠️ Component Overview The typical installation includes:

Flight Guidance Computer: The main "head" unit (Programmer).

Mounting Tray: Must be properly bonded to the airframe to prevent interference.

Servos: Pitch and Roll servos with specific mounting brackets for your airframe. Modern installations often include the GPSS converter module

Transducers: Includes a pressure transducer for altitude hold functions.

Switches: External switches for AP Disconnect, CWS (Control Wheel Steering), and Trim Master. 🔌 Wiring & Pinout Essentials

Detailed wiring diagrams are aircraft-specific, but standard conventions apply:

Shielding: Use shielded wire for sensitive data lines, grounding the shield only at one end as specified.

Solder Sleeves: Recommended for neat and reliable shield terminations (e.g., Raychem S02-08). In summary, the "S-tec 55x Installation Manual" is

Minimum Power: System requires at least 8 volts for stable operation. Pin Examples:

Pins 36 & 37: Often used for shielded 2-conductor wire (White/Blue) for digital data. Pin 46: Common shield ground point. ⚙️ Configuration & Ground Tests

Once installed, the system must undergo specific bench and flight line tests: S-TEC 55x installation guide (wiring) - BeechTalk.com


Before physical installation begins, the installing agency (typically an FAA Part 145 Repair Station or holder of an Inspection Authorization) must determine the certification basis.

The Installation Manual concludes with a mandatory ground test procedure, often referred to as the Built-In Test Equipment (BITE) sequence.

  • Static Leak Check: Apply a slight vacuum to the static line to the autopilot to verify the altitude hold engages and the aircraft does not pitch wildly during the ground test.
  • The 55X uses an altitude transducer (encoder) for altitude hold functions.

    The 55X requires complex interfacing with the aircraft’s existing systems. This is the most labor-intensive phase of the installation.