190-00498-07 Rev. A
Garmin G1000 Pilot’s Guide for Cessna Nav III
459
AUTOMATIC FLIGHT CONTROL SYSTEM
SYSTEM
OVERVIEW
FLIGHT
INSTRUMENTS EIS AUDIO PANEL
& CNS
FLIGHT
MANAGEMENT
HAZARD
AVOIDANCE AFCS ADDITIONAL
FEATURES APPENDICES INDEX
7.5 AUTOPILOT OPERATION
NOTE: Refer to the POH for specific instructions regarding emergency procedures.
Theautopilotoperatesightcontrolsurfaceservostoprovideautomaticightcontrol.Pitchandrollcommands
are provided to the servos,basedontheactiveight directormodes.Theautopilotuses pitchandrollratesto
stabilizetheaircraftattitudeduringupsetsandight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 ser vo.
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ser vo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
NOTE: 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ightdirector(ifnotalreadyengaged)areactivated.Engagement
isindicatedbyagreen‘AP’annunciationin thecenteroftheAFCSStatusBox. Theightdirectorengagesin
PitchandRollHoldmodeswheninitiallyactivated.
Figure 7-26 Autopilot Engaged
Autopilot
Engaged