Cirrus DESIGN SR20 Information Manual page 318

Section 9
Supplements
Section 1 - General
This airplane is equipped with an S-TEC System 55X Autopilot. The
System 55X autopilot is a two-axis autopilot system. The system
consists of a flight guidance programmer/computer, altitude encoder,
altitude selector / alerter, turn coordinator, and HSI. Mode selection
and vertical speed selection is made on the programmer/computer
panel. A button on each control yoke handle may be used to
disengage the autopilot. The autopilot makes roll changes through the
aileron trim motor and spring cartridge and makes pitch changes for
altitude hold through the elevator trim motor. The SR20 installation of
the S-Tec System 55X Autopilot features:
• Heading Hold and Command;
• NAV/LOC/GS tracking, high and low sensitivity, GPSS roll
steering, and automatic 45° course intercept;
• Altitude Hold and Command; and
• Vertical Speed Hold and Command.
Refer to S-Tec System Fifty-Five X Autopilot Pilot's Operating
Handbook (POH): Serials 1005 thru 1336; P/N 87109 dated 8
November 2000 or later OR Serials 1337 and subsequent; P/N 87247
original release or later for full operational procedures and description
of implemented modes. The System 55X POH also contains detailed
procedures for accomplishing GPS & VOR course tracking, front
course and back course localizer approaches, and glideslope tracking.
The SR20 implementation of the System 55X Autopilot does
not utilize the optional remote annunciator, roll servo, and
optional trim servo. Therefore, all references to these items in
the S-Tec System 55X POH shall be disregarded. Additionally,
this installation does not utilize a CWS (Control Wheel
Steering) switch or an AUTOPILOT MASTER switch.
This installation utilizes the airplane's pitch and roll trim
actuators to affect steering changes. Therefore, the automatic
trim function of the System 55X is not implemented. Disregard
all references in the S-Tec System 55X POH to this feature.
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• Note •
Cirrus Design
SR20
P/N 11934-S13
Revision 04: 08-15-07