Garmin G3X - Page 757

190-01115-01 G3X™/G3X Touch™ Avionics Installation Manual
Rev. AV Page A-6
11)
Vertical Speed
Gain Tuning
The autopilot should now be performing very well in PIT mode and in all the lateral
modes. If you are not satisfied with the PIT mode performance, or with any of the
lateral mode performances, do not continue. If this is the case, go back to the
previous two steps and continue to turn the Pitch Servo Gain and Roll Servo Gain
until you are satisfied with the performance. If you cannot successfully set your
Pitch Servo Gain and Roll Servo Gain to your satisfaction, contact Garmin at
g3xpert@garmin.com
for assistance and send us the flight data logs you should
have logged on your SD card.
Now we will tune the Vertical Speed Gain. The vertical speed gain depends on the
pitch servo gain for controlling the pitch servo. The vertical speed gain is the gain
that is adjusted to get reliable performance in VS mode which ALT mode depends
on.
Place the autopilot in VS/ROL mode commanding a bank angle of zero and a
vertical speed setting of zero fpm.
To tune the vertical speed gain, allow the aircraft to settle in its steady state, then
use the control stick to over-power the servo and displace the aircraft from the
desired vertical speed of zero. The pilot should pull or push the stick to up or down
for roughly one-two seconds to establish a new rate of climb or decent, and then
release the stick.
After releasing the control stick see the AP response by watching the control stick
and vertical speed indicator. The aircraft should return to the desired vertical speed
of zero without being too aggressive or lazy.
To increase the aggressiveness of the vertical speed response, increase the
vertical speed gain.
To decrease the aggressiveness of the vertical speed response, decrease the
vertical speed gain.
12)
Verify Altitude
Hold
Altitude hold performance depends on the Vertical Speed gain.
Once the vertical speed gain has been set, place the autopilot in ALT/ROL mode
and verify it can acceptable hold altitude. If the autopilot struggles to hold altitude
acceptably, return the previous step and continue to tune the vertical speed gain. If
you cannot successfully set your Vertical Speed Gain to your satisfaction, contact
Garmin at g3xpert@garmin.com
for assistance and send us the flight data logs you
should have logged on your SD card.
13)
Verify Altitude
Capture
Once altitude hold tuning is complete, it is possible to check that altitude capture is
working correctly and make any needed adjustments using the Vertical Accel gain.
The vertical accel gain is most often left set at 1.00, but can be adjusted when
necessary to improve altitude captures when climbing or descending in VS or VNAV
mode.
1. Climb to a selected altitude target in VS mode and note the altitude capture.
2. Set the vertical accel gain higher if the aircraft objectionably overshoots the
altitude target before leveling off at the correct altitude.
3. Set the vertical accel gain lower if the aircraft objectionably undershoots the
altitude target before leveling off at the correct altitude.
Table A-1 Flight Test Outline
Task Description