Autopilot; Flight Control - Garmin G1000 NXi Pilot's Manual

AUTOMATIC FLIGHT CONTROL SYSTEM

7.4 AUTOPILOT

Refer to the POH for specific instructions regarding emergency procedures.
NOTE:
The autopilot operates flight control surface servos to provide automatic flight control. Pitch and roll commands
are provided to the servos, based on the active flight director modes. The autopilot uses pitch and roll rates to
stabilize the aircraft attitude during upsets and flight director maneuvers. Flight director commands are rate- and
attitude-limited, combined with pitch and roll damper control, and sent to the pitch and roll servo motors.
Pitch autotrim provides trim commands to the pitch trim servo to relieve any sustained effort required by the
pitch servo. 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 servo may be used to provide manual electric trim (MET).
This allows the aircraft to be trimmed using a control wheel switch rather than the trim wheel. Manual trim
commands are generated with the MET Switch. Trim speeds are scheduled with airspeed to provide more
consistent response.
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.

FLIGHT CONTROL

Pitch and roll commands are provided to the servos based on the active flight director modes. Yaw damping
is 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.
PITCH AXIS AND TRIM
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 servo may be used to provide manual electric pitch
trim (MET). This allows the aircraft to be trimmed using a control wheel switch rather than the trim wheel.
Manual trim commands are generated only when both halves of the MET Switch are operated simultaneously.
Trim speeds are scheduled with airspeed to provide more consistent response.
ROLL AXIS
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.
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Garmin G1000 NXi Pilot's Guide for the Cessna Nav III
190-02177-00 Rev. A