Autopilot And Yaw Damper Operation - Garmin Cirrus Perspective SR20 Pilot's Manual

AUTOMATIC FLIGHT CONTROL SYSTEM

AUTOPILOT AND YAW DAMPER OPERATION

Refer to the POH for specific instructions regarding emergency procedures.
NOTE:
The autopilot and optional yaw damper (not available in the SR20) operate the flight control surface servos to
provide automatic flight control. The autopilot controls the aircraft pitch and roll attitudes following commands
received from the flight director. Pitch autotrim provides trim commands to the pitch trim servo to relieve any
sustained effort required by the pitch servo. Autopilot operation is independent of the yaw damper.
The yaw damper reduces Dutch roll tendencies, coordinates turns, and provides a steady force to maintain
directional trim. It can operate independently of the autopilot and may be used during normal hand-flight
maneuvers. Yaw rate commands are limited to 6 deg/sec by the yaw damper.
FLIGHT CONTROL
Pitch and roll commands are provided to the servos based on the active flight director modes. Yaw commands
are provided by the yaw servo. Servo motor control limits the maximum servo speed and torque. The servo
mounts are equipped with slip-clutches set to certain values. This allows the servos to be overridden in case
of an emergency.
P A
itch XiS And
The autopilot pitch axis uses pitch rate to stabilize the aircraft pitch attitude during flight director maneuvers.
Flight director pitch commands are rate and attitude-limited, combined with pitch damper control, and sent
to the pitch servo motor. The pitch servo measures the output effort (torque) and provides this signal to the
pitch trim servo. The pitch trim servo commands the motor to reduce the average pitch servo effort.
When the autopilot is not engaged, the pitch trim adapter may be used to provide manual electric trim
(MET). This allows the aircraft to be trimmed using a control stick switch. Manual trim commands are
generated only when the MET Switch are pressed. Trim speeds are scheduled with airspeed to provide more
consistent response.
When the autopilot is engaged, the MET Switch does not respond.
NOTE:
r A
oll XiS
The autopilot roll axis uses roll rate to stabilize aircraft roll attitude during flight director maneuvers. The
flight director roll commands are rate- and attitude-limited, combined with roll damper control, and sent to
the roll servo motor.
y A
Aw XiS
The yaw damper uses yaw rate and roll attitude to dampen the aircraft' s natural Dutch roll response. It also
uses lateral acceleration to coordinate turns and reduce or eliminate the need for the pilot to use rudder pedal
force to maintain coordinated flight during climbs and descents.
Cirrus Perspective
460
t
riM
by Garmin – Pilot's Guide for the SR20/SR22/SR22T
™
190-00820-08 Rev. A