S-tec 55x Installation Manual

The S-Tec 55X installation manual provides troubleshooting guides and maintenance procedures for common issues, including:

Servos must be mounted using the exact brackets specified in the aircraft-specific STC kit.

Use shielded, twisted-pair wire (MIL-C-27500) for all signal lines, including servo tachometer lines, turn coordinator inputs, and navigation bus lines.

Manually move the control stick/yoke through its full range of motion (left, right, forward, aft). Ensure there is zero rubbing, binding, or unusual resistance from the autopilot servos. S-tec 55x Installation Manual

A formal sign-off stating the system was installed in accordance with the S-TEC 55X Installation Manual, ground tested, and found airworthy.

Technicians must check for service bulletins (SB) or required revisions, such as those related to AP Steering Information Kits (e.g., Kit No. 767-316/317/318/319/320), which may modify the standard installation procedure for specific aircraft models.

: The main "head" unit (Programmer).

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

Turn the heading bug to the left; the yoke must turn to the left. Pull the pitch control aft to simulate a descent; the autopilot should command forward elevator (or auto-trim) to correct it. Ensure all movements match the commanded guidance. Conclusion: Safety First Ensure there is zero rubbing, binding, or unusual

Before diving into the manual’s technical steps, it is essential to understand how the System 55X operates. Unlike older, heavier legacy autopilots that rely on vacuum-driven artificial horizons, the S-TEC 55X is primarily a rate-based autopilot. It derives its roll and turn rate information from a turn coordinator or a modern digital air data computer/AHRS unit.

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:

Once mechanical and electrical installations are complete, a formal ground test protocol must be executed before the aircraft can be cleared for a test flight. 1. Visual Inspection and Continuity Checks Verify all structural fastners are torqued and marked. Ensure there is zero rubbing