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semmett
06-27-2012, 10:12 AM
In the efis mode, lat heading, the heading continually hunts back and forth 5 degrees. In lat arm mode it's as steady as a rock. Any suggestions?

Rob Hickman
06-27-2012, 02:41 PM
Step 2a Adjusting Autopilot Lateral Gain Settings

Whenyou adjust the heading bug to a new heading over 90 degrees away the planeshould capture the new heading with minimal overshoot.

Thereare two Gain settings that control how the airplane responds in Lateralcontrol.

EFISROLLGAIN ; This is set in the EFIS AP/FD -> SETTINGS -> LATERAL -> ROLLGAIN
APLateral Activity ; This is set in theAutopilot

TheEFIS ROLLGAIN controls how far the airplane should bank for a new heading. TheAP Lateral Activity controls how fast the autopilot roll servo responds to rollcommands.

STEP1 ADJUSTING THE AP SETTINGS


Verify that the AP LAT Torque is set to 12
Engage the Autopilot using the AP button so that the aircraft is following the heading knob on the Autopilot.
Adjust the LAT ACT on the autopilot so that the aircraft performs well when you turn to a new heading using the AP knob. You should make turns of over 90 degrees and continue to adjust until you are satisfied with the results.

STEP2 ADJUSTING THE EFIS SETTINGS

Youcan check the current commanded bank angle being sent from the EFIS to the AP fromthe check list page, it is displayed asAP ROLL. The EFIS uses the followingcalculation for AP Roll angle.

APROLL = (Heading Bug – Magnetic Heading) * EFIS ROLLGAIN

HeadingBug 090
MagneticHeading 360
EFISROLLGAIN .05

APROLL = (90 – 360) x .05
= -13.5 degrees of bank angle

TheEFIS limits the maximum bank angle to what is required for a standard rateturn.



Engage the Autopilot using the EFIS button so that the aircraft is following the heading bug on the EFIS.
Adjust the ROLLGAIN on the EFIS so that the aircraft performs well when you turn to a new heading. You should make turns of over 90 degrees and continue to adjust until you are satisfied with the results.

Ifthe EFIS ROLLGAIN is set too low the airplane will tend to be sluggish and slowto respond to new headings. If the EFISROLLGAIN is set too high the airplane will tend to overshoot the heading bugand be jittery.