Garmin G1000 NAV III Line Maintenance Manual page 173

4.10.2.3 Autopilot Clutch Overpower Check
The GFC 700 uses electronic torque limiting as well as mechanical slip clutches to limit the
maximum servo effort. When the system is on the ground, the electronic torque limiting is
removed, allowing manual checks of the slip-clutch settings. The clutch overpower check is not
necessary if the GSM 85 servo mount was not changed or serviced.
1. Engage the Autopilot by pressing the AP key.
2. Apply force to the control yoke to determine if the Autopilot clutches can be overpowered in pitch and roll.
Overpowered means that the control surfaces can be moved by applying force to the control wheel or the
rudder pedals against the resistance of the engaged Autopilot. If the Autopilot clutches cannot be
overpowered, check the servo clutch torque settings.
3. Actuate the MET switch (this causes an Autopilot disconnect). While the trim is running, grasp the aircraft
pitch trim wheel and verify that the trim clutch can be overpowered by preventing the trim wheel from
moving. If it cannot be overpowered, check the trim servo clutch torque setting. Verify also that the trim
wheel moves smoothly in both directions throughout the entire trim range during MET operation. If the trim
wheel hesitates excessively (more than 2 seconds without motion), this may indicate that the pitch trim clutch
is slipping. First verify proper clutch setting and cable tension. If both clutch setting and cable tension are
within tolerance, check the aircraft pitch trim system for excessive friction.
4.10.2.4 Manual Electric Trim Speed Check
1. Run MET in one direction until it runs against the stop.
2. Using a stop watch or equivalent device, time the trim speed from one end of travel to the opposite stop. The
elapsed time should measure 14 ± 2 seconds for each direction.
4.10.2.5 Autopilot Operation Checks
1. Push the HDG knob in to synchronize the heading bug to the present aircraft heading on the HSI.
2. Engage the Autopilot by pressing the AP key.
3. Select Heading mode by pressing the HDG key on the MFD. The command bars should be level and the
control wheel should be stationary (very slow movement acceptable, due to the aircraft not being perfectly
level).
4. Turn the HDG knob to the left and verify that the command bars move to the left and the control wheel turns
to the left (counter-clockwise).
5. Turn the HDG knob to the right and verify that the command bars move to the right and the control wheel
turns to the right (clockwise).
6. Push the CWS button and verify that "CWS" is annunciated in white on the PFD. Pull the control wheel to
the middle of the pitch control range.
7. Release the CWS button. Verify that the Autopilot clutches re-engage and hold the wheel stationary.
8. Holding the control wheel lightly, turn the NOSE UP button to increase the pitch reference. Verify that the
command bars move up approximately 1/2 degree and the control wheel begins moving aft.
9. Hold the control wheel and press the CWS button, re-synchronizing the pitch reference and re-centering the
control wheel.
10. Release the CWS button and verify that servo clutches re-engage before releasing the control wheel.
11. Press the NOSE DN button. Verify that the command bars command down and the control wheel begins
moving forward.
12. Hold the controls and press CWS to re-center the command bars and stop control wheel movement.
G1000 Nav III Line Maintenance Manual
190-00352-00
NOTE
Page 4-47
Rev. L