AUTOMATIC FLIGHT CONTROL SYSTEM
7.5 AUTOPILOT OPERATION
Refer to the AFM for specific instructions regarding emergency procedures.
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 only when both halves of the AP TRIM Switch are operated simultaneously. 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.
ENGAGING THE AUTOPILOT
Autopilot engagement/disengagement is not equivalent to servo engagement/disengagement. Use
the CWS Button to disengage the pitch and roll servos while the autopilot remains active.
When the AP Key is pressed, the autopilot and flight director (if not already engaged) are activated. Engagement
is indicated by a green 'AP' annunciation in the center of the AFCS Status Box. The flight director engages in
Pitch and Roll Hold modes when initially activated.
Figure 7-26 Autopilot and Yaw Damper Engaged
Garmin G1000 Pilot's Guide for Diamond DA40/40F
190-00592-06 Rev. A