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AUTOPILOT GFC700

This section contains supplemental information to operate, in a safe and efficient manner, the aircraft when equipped with GFC 700 autopilot device interfacing WT G1000Nxi.

LIMITATIONS

Following operating limitations shall apply when the aircraft is equipped with Garmin GFC700 Autopilot:
  • During Autopilot operation, a pilot with seat belt fastened must be seated at the left pilot position;
  • The autopilot and yaw damper must be DISENGAGED during take-off and landing;
  • The use of autopilot during single engine operation is PROHIBITED;
  • The speed envelope for autopilot operations is from 86 KIAS or stall warning activation, whichever comes first, up to 200 KIAS;
  • The Autopilot is certified for Category I - Approaches [with a decision height not lower than 200 ft AGL (61m)];
  • Minimum altitude AGL for Autopilot operation is:
    (a) All modes, except Precision Approach Mode: 500 ft (152m) AGL;
    (b) CAT I precision approach: 200 ft (61m) AGL.
  • The use of autopilot in approach is limited at 2300 RPM or less;
  • Maximum allowable fuel unbalance with autopilot engaged is 50 Liters (13 U.S. Gallons.

EMERGENCY PROCEDURES

ELECTRICAL TRIM MALFUNCTION

In case of Electric Trim malfunction (either in AP Autotrim mode or when manually operated through the Manual Electric Trim Switch), apply following procedure:
  1. 1.
    AP DISC switch ............................................. PRESS and HOLD
  2. 2.
    TRIM DISC switch ................................................................ OFF
  3. 3.
    TRIM circuit breaker ........................................................... PULL
  4. 4.
    AP DISC switch .......................................................... RELEASE

ENGINE FAILURE DURING AUTOPILOT OPERATION

  1. 1.
    Control wheel/Rudder pedals ............. HOLD and OVERPOWER if necessary to regain aircraft control
  2. 2.
    AP DISC switch ...................................................................... PRESS
  3. 3.
    AP MASTER switch ..................................................................... OFF
  4. 4.
    Engine failure in flight procedure .................................... COMPLETE

NORMAL PROCEDURES

PRE-FLIGHT CHECKS

AIRCRAFT PRE-FLIGHT CHECKS:
1. MASTER switch ..................................................................... ON
2. AUTOPILOT MASTER switch ............................................... ON
3. AUTOPILOT SELFTEST ......................................... COMPLETE
4. MANUAL ELECTRIC TRIM (MET) SYSTEM ..................... TEST
Pitch Trim: cycle fully up and down, then set to NEUTRAL.
  1. 5.
    A/P MODE selector switch .............................................. PRESS
  2. 6.
    MANUAL ELECTRIC TRIM (MET) SYSTEM ..................... TEST
Pitch Trim: move and verify A/P disconnects.

DESCRIPTION

P2012 aircraft is equipped, as an optional equipment, with an integrated 3-axis autopilot suite manufactured by Garmin and identified as AFCS (Automatic Flight Control System) GFC 700. This autopilot suite was designed as an option for the G1000Nxi integrated flight deck. The autopilot is controlled via dedicated keys grouped in a control panel (GMC 710) located above the MFD.
Electrical power control switches of the autopilot are located on the instrument panel:
  • Autopilot Master Switch: provide electrical power to the autopilot system
  • Trim Disconnect Switch: provide electrical power to the pitch trim servo
Autopilot controller is provided by means of GMC 710. The GMC 710 provides the pilot an interface with the GFC 700 Automatic Flight Control System, with which is linked through the PFDs, via RS-232 digital interface. The AFCS Control unit is positioned above the MFD as shown in the figure below:
Instrument panel - Autopilot Controller/Switches location

AUTOPILOT MODE CONTROLLER

GMC 710 Provides the controls for the Garmin AFCS through an RS-232 digital interface allowing communication with both PFDs.
GMC 710 AFCS Control unit
The AFCS Control Unit consists of the following controls:
  1. 1.
    HDG Key - Selects/deselects Heading Select Mode.
  2. 2.
    APR Key - Selects/deselects Approach Mode.
  3. 3.
    NAV Key - Selects/deselects Navigation Mode.
  4. 4.
    FD Key - Activates/deactivates the flight director in the default pitch and roll modes. If the autopilot is engaged, the FD Key is disabled.
  5. 5.
    XFR Key - Switches the autopilot between the pilot-side and the copilot-side flight directors. This selection also selects which air data computer is communicating with the active transponder. Upon power- up, the pilot-side FD is selected.
  6. 6.
    ALT Key - Selects/deselects Altitude Hold Mode.
  7. 7.
    VS Key - Selects/deselects Vertical Speed Mode.
  8. 8.
    FLC Key - Selects/deselects Flight Level Change Mode.
  9. 9.
    CRS2 Knob - Sets the copilot-selected course on the HSI of PFD2 when the VOR1, VOR2, or OBS/SUSP mode is selected. Pressing this knob centers the CDI on the currently selected VOR. The copilot- selected course provides course reference to the copilot-side flight director when operating in Navigation and Approach modes.
  10. 10.
    SPD Key - Switches the Flight Level Change mode reference speed between IAS and MACH number (function not available for G1000Nxi).
  11. 11.
    UP/DN Wheel - Controls the active mode reference for the Pitch, Vertical Speed, and Flight Level Change modes.
  12. 12.
    VNV Key - Selects/deselects Vertical Navigation mode.
  13. 13.
    ALT SEL Knob - Sets the selected altitude in the Selected Altitude Box. In addition to providing the standard G1000Nxi altitude alert function, selected altitude provides an altitude setting for the Altitude Capture/Hold mode of the AFCS.
  14. 14.
    YD Key - Engages/disengages the yaw damper.
  15. 15.
    AP Key - Engages/disengages the autopilot.
  16. 16.
    BANK Key - Selects/deselects Low Bank Mode.
  17. 17.
    CRS1 Knob - Sets the pilot-selected course on the HSI of PFD1 when the VOR1, VOR2, or OBS/SUSP mode is selected. Pressing this knob centers the CDI on the currently selected VOR. The pilot- selected course provides course reference to the pilot-side flight director when operating in Navigation and Approach modes.
  18. 18.
    BC Key - Selects/deselects Back Course Mode.
  19. 19.
    HDG Knob - Sets the selected heading on the HSI. When operating in Heading Select mode, this knob provides the heading reference to the flight director.

PILOT CONTROL WHEEL AND THROTTLE BUTTONS/SWITCHES

Control wheel and PTT switch
Throttle and TO/G.A. Button
The following additional dedicated AFCS controls are located on the pilot control wheel:
  1. 2.
    AP DISC Switch - Disengages the autopilot and interrupts pitch trim operation This switch may be used to mute the aural autopilot disconnect alert.
  2. 3.
    Trim Switch - Used to command manual electric trim. This composite switch is split into left and right sides. The left switch is the ARM contact and the right switch controls the DN (forward) and UP (rearward) contacts. The switch can be used to disengage the autopilot and to acknowledge an autopilot disconnect alert and mute the associated aural tone. Manual trim commands are generated only when both sides of the switch are operated simultaneously. If either side of the switch is active separately for more than three seconds, MET function is disabled and ‘PTRM’ is displayed as the AFCS Status Annunciation on the PFD. The function remains disabled until both sides of the switch are inactivated.
  3. 4.
    CWS Button - While pressed, the Control Wheel Steering allows manual control of the aircraft while the autopilot is engaged and synchronizes the flight director’s Command Bars with the current aircraft pitch (if not in Glideslope Mode) and roll (if in Roll Hold Mode). Upon release of the CWS Button, the flight director may establish new reference points, depending on the current pitch and roll modes. CWS operation details are discussed in the flight director modes section.
  4. 5.
    TO / G.A. Button - The TO/G.A. Button is located on the throttle left handle (left side). Go Around and Take-off modes are coupled pitch and roll modes and are annunciated as both the vertical and lateral modes when active. In these modes, the flight director commands a constant set pitch attitude and keeps the wings level. The TO/G.A. Button is used to select both modes. The mode entered by the flight director depends on whether the aircraft is on the ground.

FUNCTIONS

The GFC 700 AFCS is equipped with the following main operating functions:
  • Flight Director (FD) - Flight director operation takes place within the primary IAU and its commands are displayed on both PFDs. The flight director provides:
    • Command Bars showing pitch/roll guidance
    • Vertical/lateral mode selection and processing
    • Autopilot communication
  • Autopilot (AP) - Autopilot operation occurs within the pitch, roll, and pitch trim servo and provides servo monitoring and automatic flight control in response to flight director steering commands, AHRS attitude and rate information, and airspeed.
  • Yaw damper (YD) - The yaw servo is self-monitoring and provides Dutch roll damping and turn coordination in response to yaw rate, roll angle, lateral acceleration, and airspeed.
  • Manual Electric Trim (MET) - The pitch trim servo provides manual electric trim capability when the autopilot is not engaged.

FLIGHT DIRECTOR

The flight director function provides pitch and roll commands to the AFCS and displays them on the PFDs.
The symbol representing the airplane and the symbol representing the direction of command control diverge as the aircraft departs from a computed steering command and converge as it returns. Departure in the direction of a left roll, or a decreased heading or course, causes the aircraft symbol to appear to move rotationally to the left with respect to the command symbol, and in the opposite direction for an increased heading. Departure in the direction of nose down pitch attitude or decreased altitude causes the aircraft symbol to appear to move below the command symbol, and in the opposite direction for a nose up departure. Control commands are satisfied when the symbols coincide.
With the flight director activated, the aircraft can be hand-flown to follow the path shown by the Command Bars. The flight director also provides commands to the autopilot.
Flight director mode annunciations are displayed on the PFDs when the flight director is active. Flight director selection and autopilot and yaw damper statuses are shown in the center of the AFCS Status Box. Lateral flight director modes are displayed on the left and vertical on the right. Armed modes are displayed in white and active in green.
Autopilot/FD status notification
Upon activation of the flight director, Command Bars are displayed on the PFDs as a single magenta cue. The Command Bars move together vertically to indicate pitch commands and bank left or right to indicate roll commands. The Command Bars do not override the aircraft symbol. If the attitude information sent to the flight director becomes invalid or unavailable, the Command Bars are removed from the display. The flight director Command Bars also disappear if the pitch or bank exceeds the angles defined at development time.
Flight Director Command Bars
Flight director modes are normally selected independently for the pitch and roll axes. Mode keys on the AFCS controller are accompanied by annunciator lights, which are illuminated when their respective modes are armed or active. Armed modes are annunciated in white and active ones in green in the AFCS Status Box. Under normal operation, when the control for the active flight director mode is pressed, the flight director reverts to the default mode(s) for the axis(es). Automatic transition from armed to active mode is indicated by the white armed mode annunciation moving to the green active mode field and flashing for 10 seconds. If the information required to compute a flight director mode becomes invalid or unavailable, the flight director automatically reverts to the default mode for that axis. A flashing yellow mode annunciation and annunciator light indicate loss of sensor (ADC) or navigation data (VOR, LOC, GPS, VNV, SBAS) required to compute commands. When such a loss occurs, the system automatically begins to roll the wings level (enters Roll Hold Mode) or maintain the pitch angle (enters Pitch Hold Mode), depending on the affected axis.
The flashing annunciation stops when the affected mode key is pressed or another mode for the axis is selected. If after 10 seconds no action is taken, the flashing annunciation stops.
Loss of VOR Signal
Take-off (TO) and Go-around (G.A.)
Go Around and Take-off modes are coupled pitch and roll modes and are annunciated as both the vertical and lateral modes when active. In these modes, the flight director commands a constant set pitch attitude and keeps the wings level. The GA Switch is used to select both modes. The mode entered by the flight director depends on whether the aircraft is on the ground.
Take-off Mode provides an attitude reference during rotation and take-off. This mode can be selected only while on the ground by pushing the GA Switch. The flight director Command Bars assume a wings-level, pitch-up attitude.
Pressing the GA Switch while in the air activates the flight director in a wings-level, pitch-up attitude, allowing the execution of a missed approach or a go around.
Go Around Mode
Take-off Mode

AUTOPILOT AND YAW DAMPER OPERATION

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. The yaw damper is automatically engaged with autopilot engagement. 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 will be limited by the yaw damper.
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 gearboxes 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
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.
A/P and Yaw Damper Engage
Autopilot and yaw damper Engaged
Autopilot and yaw damper status are displayed in the center of the AFCS Status Box. Engagement is indicated by green ‘AP’ and ‘YD’ annunciations, respectively.
CWS (Control Wheel Steering)
During autopilot operation, the aircraft may be hand-flown without disengaging the autopilot. Pressing and holding the CWS Button disengages the pitch and roll servos from the flight control surfaces and allows the aircraft to be hand-flown. At the same time, the flight director is synchronized to the aircraft attitude during the maneuver. CWS activity has no effect on yaw damper engagement.
The ‘AP’ annunciation is temporarily replaced by ‘CWS’ in white for the duration of CWS maneuvers. In most scenarios, releasing the CWS Button reengages the autopilot with a new reference. Refer to the flight director modes section for specific CWS behavior in each mode.
AP and Yaw Damper Disconnect
To manually disengage only the autopilot and not the Yaw Damper push the AP Key on the AFCS Control Unit, the GA Switch or the MET ARM Switch. Other ways to disconnect the autopilot include pulling autopilot circuit breaker or AP MASTER Switch or AP DISC Button activation. Manual autopilot disengagement is indicated by a five-second flashing yellow ‘AP’ annunciation and a three-second autopilot disconnect aural alert. After manual disengagement, the autopilot disconnect aural alert may be cancelled by pushing the AP TRIM ARM or AP DISC Switch.
Pushing the AP DISC Switch or YD disengages both the yaw damper and the autopilot. When the yaw damper and autopilot are manually disengaged, both the ‘AP’ and ‘YD’ annunciation turn yellow and flash for three seconds and a three-second autopilot disconnect aural alert is generated.
After manual disengagement, the autopilot disconnect aural alert may be cancelled by pushing the MET ARM or AP DISC Switch (AP DISC Switch also cancels the flashing ‘AP’ annunciation). Automatic autopilot disengagement is indicated by a flashing red and white ‘AP’ annunciation and by the autopilot disconnect aural alert, which continue until acknowledged by pushing the AP DISC or MET ARM Switch. Automatic autopilot disengagement occurs due to:
  • System failure
  • Invalid sensor data
  • Yaw damper failure while both are engaged
  • Stall warning device activation
  • Inability to compute default flight director modes (FD also disengages automatically)
Yaw damper disengagement is indicated by a five-second flashing yellow ‘YD’ annunciation. Automatic yaw damper disengagement occurs when autopilot disengagement is caused by failure in a parameter also affecting the yaw damper. This means the yaw damper can remain operational in some cases where the autopilot automatically disengages.

MANUAL ELETRIC TRIM

Manual Electric Trim function is embodied in the system. This function allows the pilot to manually operate the pitch trim servo while the aircraft is hand-flown. The installed switch type is made of two sides. The pitch trim will actually move only if both sides of the switch are pressed simultaneously. No manual trim motor command is generated unless both the ARM switch and either the UP or DN switch is active simultaneously. If the ARM switch or the UP/DN switch is active for more than 3 seconds without the other switch, the trim switches are ignored until both switches are inactive.