Trio Avionics EZ Pilot - v 1.9 User Manual
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The servo crank arm uses a pushrod terminated by rod end bearings to link the servo arm to the
aircraft aileron control system. The pushrod provided in the installation kit should be trimmed to
the correct length for your particular installation.
In your installation, it may be more convenient to rotate the crank arm to a new orientation that
will give a neutral (servo center position) at +/- 90 degrees or 180 degrees from that as supplied
from the factory. The servo crank arm is secured to a flange by four machine screws that can be
removed for indexing the crank arm in 90 degree increments.
In most cases the servo is installed with the bottom of the servo parallel to the ground, but it
operates equally well in any orientation.
There are four holes in the crank arm that give operating radii with the combinations of force and
peak-to-peak travel listed in Table 1 below:
Crank Arm Radius
Max. Travel (peak-to-peak)
Force (in-lb)
1.0 inch
1.5 inch
30
1.2 inch
1.8 inch
25
1.4 inch
2.1 inch
21
1.6 inch
2.4 inch
19
Choose an operating radius on the servo crank arm that allows full aileron movement
(aileron stop to aileron stop) without driving the servo crank arm into its limits (+/- 50
degrees). Most aircraft get best performance in the 3
rd
or 4
th
(outermost) hole.
7.2 Servo Mounting Hardware
A hardware mounting kit is shown below. A hex shaped rod is provided, with two rod end
bearings attached. Typically, one of these connects to the servo crank arm and the other
is strapped to the aileron pushrod using the clamps provided (as shown in a later
illustration). When the servo is connected to the aileron control system it should be
installed so that the servo crank arm is at a right angle to the control rod. This
mechanically centers the servo mechanism to the control system so that there is equal
displacement in either direction when the servo is actuated. Fine zeroing using electrical
trim will be accomplished later in paragraph 7.6.4.
Connects to
Aileron Pushrod
Using Clamps
Connects to
Servo Crank Arm
Note: It is important to assure that the proper direction of travel is
preserved when modifying the crank arm orientation. Changing the
crank arm mounting by 180 degrees will essentially reverse the
direction of travel for the servo arm. In such a case the EZ Pilot
control head must be programmed to reverse the drive signal.