Technical data

13773-001
22-10
Page 131 July 2001
SYSTEM 55 AUTOPILOT
1. DESCRIPTION
The S-TEC System 55 is a dual axis autopilot system that provides roll stability, heading hold, NAV/GPS
tracking, altitude hold, vertical speed selection, automatic glideslope capture, and automatic 45 ° intercept
to desired flight path capabilities controlled via the roll-trim cartridge and pitch servo.
The system components consist of a Flight Guidance Programmer/Computer, Altitude Selector/Alerter,
Altitude Transducer, and Pitch Servo. The operating controls for the autopilot are located on the Flight
Guidance Programmer/Computer.
Through panel mounted switches and the vertical speed knob, the Flight Guidance Programmer/Computer
serves the function of converting operator commands to logic signals for the roll and pitch computer func-
tions. The integrated roll computer receives signal inputs from the Turn Coordinator and HSI to compute
roll commands for stabilization, turns, radio intercepts, heading and tracking. The integrated pitch com-
puter receives signal inputs from the Altitude Transducer, accelerometer, glideslope deviations, and Alti-
tude Selector/Alerter.
2. MAINTENANCE PRACTICES
A. Flight Guidance Programmer/Computer (See Figure 22-101)
(1) Removal - Flight Guidance Programmer/Computer
(a) Ensure BAT 1, BAT 2, and AVIONICS master switches are in off position.
(b) Pull AUTOPILOT circuit breaker.
(c) Insert allen wrench into front panel bolt hole and engage allen bolt.
(d) Turn locking screw counterclockwise to loosen locking cam. Cam will move the trans-
ceiver unit out 1/4” and disengage from the electrical connectors.
(e) Pull Flight Guidance Programmer/Computer from mounting tray
(2) Installation - Flight Guidance Programmer/Computer
(a) With light to medium pressure, push Guidance Programmer/Computer into mounting tray
to engage electrical connectors.
(b) Insert allen wrench into front panel bolt hole and engage allen bolt.
(c) Turn bolt clockwise to tighten locking cam.
(d) Reset AUTOPILOT circuit breaker.
B. Altitude Selector/Alerter (See Figure 22-101)
(1) Removal - Altitude Selector/Alerter
(a) Ensure BAT 1, BAT 2, and AVIONICS master switches are in off position.
(b) Pull AUTOPILOT circuit breaker.
(c) Remove MFD. (Refer to 34-40)
(d) Disconnect cable from Altitude Selector/Alerter.
(e) Remove screws securing Altitude Selector/Alerter to instrument panel.
(f) Remove Altitude Selector/Alerter from airplane.
(2) Installation - Altitude Selector/Alerter
(a) Align Altitude Selector/Alerter over instrument panel mounting holes and secure with
screws.
(b) Connect cable to Altitude Selector/Alerter.
(c) Install MFD. (Refer to 34-40)
(d) Reset AUTOPILOT circuit breaker.