TruTrak Yaw Damper - Manual (Page 5)

TruTrak Flight Systems Yaw Damper Installation Manual
December 2009 3 8300-063 Rev C
not become slack. If the bridle cable is not sufficiently tight there will be lost motion in the
autopilot drive. This will result in hunting (oscillation).
Yaw Damper Initial Setup & Checkout
The next step in the installation procedure is to verify electrical operation of the yaw damper.
Before this test, remove the yaw damper module from its mounting location so that it can be
manually tilted. Verify the direction strap is correctly wired on pins 17 and 18 of J501, the 25-pin
yaw damper connector. If the unit is to be mounted on the rear side of a bulkhead, connector
pointing aft, the strap between pins 17 and 18 of J501 must be
absent . If the unit is to be
mounted on the front side, connector pointing forward, the jumper must be present. Enter the Yaw
Damper setup mode in the autopilot controller, advance to and set YD ACTIVITY value to 15.
Advance to the MIN AIRSPD field, set the minimum airspeed to 0. MIN airspeed must be set to
0 on the ground to engage the YAW damper.
Having verified the strap, manually center the rudder and then engage the yaw damper by
following the correct procedure (see autopilot installation manual) for the autopilot programmer.
Position the toggle switch on the YD module in the
GYRO “OFF” position to set the centering,
hold the yaw damper module in the same position it will occupy when mounted on the bulkhead
in an approximately level position that stops the servo rotation. Tilt the module to simulate the
aircraft banking to the right. The yaw damper should respond by commanding the rudder to move
towards the right, and conversely a bank to the left should move the rudder towards the left. If the
servo moves in the wrong direction during this test, double-check the correct jumper setting on
pins 17 and 18 and if found to be correct, interchange the wires on the yaw damper servo
connector (pins 4 and 5 of J401) or at the connector on the yaw damper module (pins 12 and 13 of
J501). Re-check the direction after exchanging the wires.
Having verified the correct direction of response to the tilt sensor, secure the yaw damper module
to the bulkhead. Re-engage the yaw damper and adjust the leveling potentiometer, the black knob
which protrudes from the face of the yaw damper module, to stop the movement of the servo
(rudder). The aircraft should be on a level surface (with its “ball” centered) for this adjustment.
Once the proper tilt adjustment is done, switch the toggle switch toward “gyro on” and push on
the tail to confirm correct servo movement. Rudder must move in direction of empennage
direction. Example: Empennage moves away from you, rudder swings way from you.
Once the proper adjustment is done and confirmed, disengage the yaw damper, re-enter the Yaw
Damper setup mode, advance to and set YD ACTIVITY value to zero. This insures that the yaw
damper adjustments do not complicate the first test flight of the autopilot. Advance to the MIN
AIRSPD field, set the minimum airspeed to the desired value for actual flight. This should be an
indicated airspeed (in knots) which is safely above the stall but below normal approach or climb
out speeds. Make sure that the toggle switch on the Yaw Damper controller is toggled toward
GYRO “ON” for flight.
The remaining adjustments relate to the dynamics of flight.