Garmin GI 275 Installation Manual page 309

6.8.6.1 Autopilot Performance
The autopilot performance can be adjusted by changing the settings on the Autopilot Calibration page
(Calibration/Test → Autopilot → Calibration) while in Configuration mode.
1. To evaluate the autopilot heading performance, center the heading bug and engage the autopilot in
HDG mode. Change the heading bug by at least 45°. The autopilot must follow the heading bug
and roll out smoothly, without undershooting or overshooting the selected heading.
2. To evaluate the autopilot course performance, engage the autopilot in NAV mode. Tune to a NAV
frequency that is out of range and select the corresponding NAV on the CDI. The GI 275 will
invalidate the lateral deviation signal. Change the course by at least 45°. The autopilot must turn to
the new course and roll out smoothly without undershooting or overshooting the selected course.
6.8.6.2 Roll Steering Performance
GPS roll steering is handled in one of three ways:
1. If the autopilot has an ARINC 429 roll steering input, the GI 275 provides ARINC 429 roll
steering directly to the autopilot.
2. If an external roll steering converter has been installed, the GI 275 provides ARINC 429 roll
steering to the converter, which then outputs an analog heading error signal to the autopilot.
3. The GI 275 can provide the roll steering via its heading error output, taking the place of a separate
roll steering converter. In this case, the autopilot is left in Heading mode, and the GI 275 varies the
heading error output to steer the autopilot.
In order to evaluate roll steering performance, perform the following:
1. Set up a GPS flight plan that includes at least two legs with an angle between them.
2. Set the CDI to display the active GPS.
3. Engage the autopilot in GPS Roll Steering mode.
4. If the autopilot uses the heading error input for roll steering, engage the autopilot in HDG mode.
5. Activate GPSS (HDG → AP HDG REF → GPSS or by using the discrete switch).
6. A "GPSS" annunciation
7. Verify that the autopilot flies the airplane smoothly through the turn between the two legs.
NOTE
the Analog Roll Steering function is utilized, the scaling of the output can be adjusted
If
using the Analog Roll Steering Scaling setting on the Autopilot Test page. If the autopilot
does not turn sharp enough while in Roll Steering mode, increase the GPSS Scaler to
HDG value. If the autopilot turns too sharp while in Roll Steering mode, decrease the
GPSS Scaler to HDG value.
6.8.6.3 Yaw Damper Operation
This check is only required if the GI 275 is used to replace an existing yaw rate sensor to provide yaw rate
information to the autopilot. During flight, verify that the yaw damp function operates correctly.
190-02246-10
Rev. 11
will appear on the display.
GI 275 Part 23 AML STC Installation Manual
Page 6-40