Specifications

P/N 11934-S27 13 of 16
Cirrus Design Section 9
SR20 Supplements
• Note •
If the HDG bug is within 5° of center and the course deviation
is less than 10%, the autopilot will immediately establish the
lowest level of sensitivity and limit the turn rate to a maximum
of 25% of a standard rate turn.
5. For increased sensitivity during approach or if desired for enroute
tracking, press the APR button on the autopilot programmer/
computer. Both NAV and APR annunciators will be illuminated.
Section 5 - Performance
There is no change to the airplane performance when the S-Tec
System 55SR autopilot is installed.
Section 6 - Weight & Balance
There is no change to the airplane weight & balance when the S-Tec
System 55SR autopilot is installed.
Section 7 - Systems Description
Autopilot
The airplane is equipped with an S-Tec System 55SR two-axis
Automatic Flight Control System (Autopilot). The autopilot
programmer/computer is installed in the center console radio stack.
The autopilot roll axis uses an inclined gyro in the turn coordinator
case as the primary turn and roll rate sensor. In addition to the turn
coordinator instrument, the roll axis computer receives signals from
the PFD and the NAV/GPS radio. The roll computer computes roll
steering commands for turns, radio intercepts, and tracking. Roll axis
steering is accomplished by autopilot steering commands to the
aileron trim motor and spring cartridge.
The pitch computer receives altitude data from the altitude encoder
pressure transducer plumbed into the static system, the PFD, and #1
NAV radio. Pitch axis command for altitude hold is accomplished by
pitch computer commands to the autopilot elevator trim motor.
28 VDC for the autopilot is supplied through the 5-amp AUTOPILOT
circuit breaker on the Essential Bus.
Revision 02: 07-18-05