S-tec 55x Installation Manual

The S-TEC 55X Installation Manual (P/N 87109 or subsequent revisions) provides core electrical and electronic specifications.

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The main unit is typically mounted in the avionics stack. The installation requires careful attention to the mounting tray. A common issue is the tray being mounted too far from the radio rack. This prevents the rear connectors from fully seating and locking before the front faceplate touches the adjacent equipment. It is crucial to ensure the tray is positioned so that the connectors are fully engaged and secure.

Wiring must comply with manufacturer and FAA standards to ensure system integrity. S-tec 55x Installation Manual

A key part of the initial setup is ensuring the autopilot is correctly configured to interface with the aircraft's heading system, typically as a KCS-55-compatible unit for DC heading systems. After confirming this in the configuration, an inflight checkout in smooth air is necessary. The technician will engage the autopilot in HDG and ALT modes, then use the PFD’s system setup mode to access the calibration page. From there, they can select "Perform A/P Cal" and then "Sync HDG" to align the autopilot's heading reference with the PFD’s heading bug.

The roll and pitch servos attach to the aircraft’s primary flight control cables using small steel aircraft cables known as bridle cables.

The S-TEC STC Installation Blueprint Drawings provide physical installation data unique to individual airframe tail numbers. The S-TEC 55X Installation Manual (P/N 87109 or

Provides the primary rate-based input for the roll axis.

Servo capstans must align perfectly with the aircraft control cables to prevent cable chafing.

For certified aircraft, the S-TEC 55X must be installed in accordance with its Supplemental Type Certificate (STC). Every aircraft make and model has a specific "STC Kit" that includes tailored brackets, hardware, and structural drawings. You must verify that your specific tail number and fuselage configuration match the Approved Model List (AML). Weight and Balance Impact A common issue is the tray being mounted

This 42-page manual dated October 29, 2013, includes parts lists for the main wire harness, turn coordinator, pressure transducer, and servo kits.

An autopilot installation cannot proceed using generic instructions. Technicians must secure the exact documentation corresponding to the specific aircraft make and model.