0110T – S-Tec Pitch Flight Guidance Computer (PFGC) with Trim Control
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Overview Section
The S-Tec 0110T is an advanced, remote-mounted Pitch Flight Guidance Computer (PFGC) designed to manage the vertical axis of an aircraft's autopilot system. Unlike basic wing-leveler systems, the 0110T provides sophisticated vertical control, including Altitude Hold, Vertical Speed (VS) command, and Glideslope (GS) coupling for precision approaches.
The "T" in the part number signifies that this specific unit includes Automatic Trim Control. This feature allows the computer to sense "out-of-trim" conditions in the pitch axis and command a dedicated trim servo to neutralize control pressures. This ensures that when the pilot disengages the autopilot, the aircraft is in a perfectly trimmed state, preventing sudden pitch "jolts." The 0110T typically functions as the vertical component for the S-Tec System 50, 60, or 65 autopilot families.
Key Features Section
Vertical Axis Guidance: Provides the electronic logic and processing required to maintain altitude and execute vertical flight profile changes.
Integrated Automatic Trim: Features built-in trim logic to manage the pitch trim servo, maintaining the aircraft in a constant "hands-off" trim state during autopilot operation.
Precision Approach Coupling: Capable of capturing and tracking ILS Glideslope signals, allowing for fully coupled instrument approaches.
Vertical Speed Selection: Allows the pilot to command specific climb or descent rates through the autopilot control head.
Remote-Mounted Design: Installed in the avionics bay or behind the panel to save space on the primary flight deck while interfacing with the main autopilot programmer.
Solid-State Reliability: Engineered with high-integrity electronic components to withstand the vibration and temperature cycles of general aviation flight.
Fail-Safe Monitoring: Includes internal monitors to detect malfunctions in the pitch or trim drive circuits, providing safety disconnects if limits are exceeded.
Technical Specifications Section
Part Number: 0110T
Model Designation: Pitch Flight Guidance Computer (PFGC)
OEM Manufacturer: S-Tec (Genesys Aerosystems)
Control Axis: Pitch (Vertical)
Trim Capability: Integrated Automatic Pitch Trim Control
Voltage: Typically 14 VDC or 28 VDC (Check specific mod status for the unit)
Input Interface: Receives signals from the pressure transducer, glide slope receiver, and main autopilot programmer.
Output Interface: Provides drive commands to the Pitch Servo and the Pitch Trim Servo.
Certification: TSO approved as part of a complete S-Tec Autopilot system installation.
Aircraft Compatibility Section
High-Performance Piston/Turboprops: Commonly found in a wide range of aircraft, including Beechcraft Bonanza/Baron, Piper Saratoga/Malibu, and Cessna 300/400 series twins.
Installation Requirements: Installation is governed by a Supplemental Type Certificate (STC) specific to the airframe, which defines the required servos and wiring.
Note: The 0110T must be matched with a compatible S-Tec pitch servo and, due to the Trim feature, a specific trim servo. The S-Tec Autopilot Installation Manual is the final authority for system compatibility and wiring.
Applications Section
Instrument Flight (IFR): Essential for reducing pilot workload during precision and non-precision approaches by maintaining vertical path accuracy.
Enroute Cruise: Holds a precise altitude, improving fuel efficiency and passenger comfort by eliminating altitude "wandering."
Transition to Landing: The Automatic Trim feature ensures a safe and stable transition from autopilot control to manual pilot control during the landing flare.
Why Choose the 0110T?
The 0110T is a critical safety and performance upgrade for any aircraft equipped with an S-Tec autopilot system. The addition of Automatic Trim is particularly vital; without it, an autopilot can "fight" an out-of-trim condition until the servo reaches its limit, at which point the autopilot may disconnect and leave the pilot with a heavy, out-of-balance flight control. The 0110T eliminates this risk by constantly adjusting the trim as the aircraft's speed or configuration changes, ensuring a safe, stable, and smooth flight experience from takeoff to touchdown.
The operation of the 0110T relies on closed-loop feedback logic. The computer monitors the vertical speed and altitude deviation from the pressure sensors and the glideslope deviation from the nav receiver. It simultaneously monitors the current draw or "torque" of the pitch servo. When the pitch servo has to apply continuous force to maintain the path—indicating the aircraft is "nose-heavy" or "tail-heavy"—the 0110T activates the Trim Control circuit. This moves the aircraft's physical trim tab until the pitch servo no longer feels the force. This "load-sensing" capability is what makes the 0110T with Trim a superior guidance computer for high-performance aircraft.
Note: The 0110T is a major avionics component. Installation and calibration must be performed by a certified avionics shop. After installation, a functional ground test and flight test are required to ensure the pitch and trim gains are adjusted correctly for the aircraft's specific flight characteristics.
Documentation
S-Tec System 50/60/65 Installation Manual: Contains detailed wiring and pin-out data for the 0110T.
Supplemental Type Certificate (STC): Defines the legal basis for the unit's installation in specific airframes.