Garmin G1000 King Air C90GT - Manual (Page 444)

Garmin G1000 Pilot’s Guide for the Beechcraft C90A/GT 190-00663-01 Rev. A 430
AUTOMATIC FLIGHT CONTROL SYSTEM
SY
STEM
O
VER
VIEW
FLIGHT
INSTRUMENTS
EIS
AUDIO P
ANEL
& CNS
FLIGHT
MANA
GEMENT
HAZARD
AV
OID
ANCE
AFCS
ADDITIONAL FEA
TURES
APPENDICES
INDEX
7.5 AUTOPILOT AND YAW DAMPER OPERATION
NOTE: Refer to the POH/AFM for specific instructions regarding emergency procedures.
The autopilot and yaw damper 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 and coordinates turns. 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 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 (MEPT). 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 MEPT 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.
YAW AXIS
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.