TruTrak DFC Install Manual - Manual (Page 13)

TruTrak Flight Systems DFC Autopilot Installation Manual
11 May 2006 Printing
DFC-300 systems require adjustment of the yaw damper parameters. With the autopilot disengaged, level the aircraft and hand-
fly the aircraft in still air. Press MODE to engage the yaw damper (the lower-left part of the display will indicate YD ON).
Then press and hold MODE to enter the setup screen. Cycle through the settings already done until YD LEVELING and YD
ACTIVITY show on the display. Centering is adjustable from -8 to 8 and has enough authority to move the ball approximately
one and one half times the width of the ball in either direction. (Coarse adjustment was made using the potentiometer in the
yaw damper module during the earlier Initial Checkout Procedure.) The next field, YD ACTIVITY, determines how
aggressively the yaw damper responds to yaw disturbances. Yaw damper activity can range from 0 (off) to 12 (extremely
aggressive). For this purpose it is best to find light to moderate turbulence so the effects can be properly observed. Having
found suitable conditions, use the knob to gradually increase the value of YD ACTIVITY in order to obtain an appropriate
level of response to yaw disturbances. Too high a value will result in rapid oscillation, while too low a value will essentially
disable the quick response of the yaw damper to turbulence. Within the acceptable range of operation, there is still room to
account for personal preferences. So long as the yaw damper’s YD ACTIVITY value is not so high as to cause oscillation, the
response is simply set according to preference and comfort.
The normal operation of the autopilot will turn the yaw damper on any time the autopilot is engaged, and the yaw damper will
stay on after the autopilot is disengaged. During final approach and the diminishing of the airspeed below the MIN AIRSPD
setting, the yaw damper will automatically disengage. To disengage the yaw damper prior to that point, simply use the MODE
button to toggle the yaw damper off. When the autopilot is in the Off mode, the MODE button acts as a yaw damper on/off
toggle function and the display will indicate YD ON or YD OFF.
This concludes the in-flight setup of the TruTrak digital autopilot.