Trio Avionics EZ Pilot - v 1.9 - Manual (Page 33)

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SERVO POS = 07500
SERVO = NORM
If you tighten the clutch enough to exceed the 30 in-lbs maximum torque rating, you may
hear a loud clacking sound in the servo and the servo may disengage. This clacking
happens when the force pushing the gears apart exceeds the solenoid’s ability to hold
the gear train engaged. This is a redundant safety feature – just back off on the control
nut a little and recycle the power switch to re-engage the servo.
7.6 Adjustment of Servo Rotation Direction and Servo Neutral
With the autopilot now fully installed, it is necessary to perform a preliminary adjustment
to the servo neutral position. This procedure will set the neutral position and also
determine the direction of servo rotation for a left or right roll correction.
7.6.1 Setup Mode Entry
With the GPS receiver turned off, turn on the EZ Pilot power switch while
simultaneously holding down the DISPLAY pushbutton. Then release the
DISPLAY pushbutton. The EZ Pilot is now in the “setup” mode. Press the
SERVO button on the control head to engage the servo. You should hear the
solenoid engage the gears and you may see some brief movement of the
ailerons. The autopilot will now be in the “servo calibration” mode with the
SERVO POSITION screen displayed. If this is an LCD model, advance to the
servo positioning screen by pressing the mode button 1 time.
7.6.2 Servo Rotation Testing
Note: The servo rotation direction is critical to flight safety and proper autopilot
operation. If this is not set correctly the autopilot will not track correctly and will
cause the airplane to roll to bank angles in excess of 30 degrees either right or left
when the servo is engaged. This setting cannot be changed in flight so it is critical
that this be set correctly during ground setup and testing.
The numbers that appear in the
readout represent the servo position.
Higher numbers position the ailerons
for a right turn and lower numbers
position the ailerons for a left turn.
Push and hold the L-R switch to the right position to increment the number to the
9000 setting (the right limit). Ensure the ailerons are positioned for a right turn,
left aileron down, right aileron up. If they are not positioned for a right turn
proceed directly to Paragraph 7.6.3 If this is okay, run the SERVO POSITION
to the extreme left (6000) position and verify proper control system movement.
This is a good time to observe that the pushrod does not rotate when the servo is
slewed to the two extreme positions. Once this is verified proceed to Paragraph
7.6.4.
Note: In older systems it was sometimes necessary to reverse internal servo wiring and/or to
fly the aircraft several times, and adjust the servo push rod position several times, to accurately
fix the neutral position. The EZ Pilot incorporates an electronic method to “zero” the servo once
it has been properly installed. This setting is then stored in the autopilot permanent memory,
thus eliminating the need to perform repetitive mechanical adjustments to achieve an accurate
neutral position.