Trio Avionics EZ Altitude Control - Manual (Page 14)

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checking that the required range of elevator movement is available within the limits
of the servo travel range, and that no “over center” condition can exist.
The servo crank arm uses a pushrod terminated by rod end bearings to link the servo
arm to the aircraft elevator control system. The pushrod provided in the installation kit
should be trimmed to the correct length for your particular installation. The servo should
be mounted on a solid platform that will not buckle or “oilcan” and attached to a firm
existing support. It is recommended that the servo platform not be mounted to the
aircraft “skin” without a doubler or some other additional support. Rigidity of the servo
mount is critical to proper servo operation. If you do not have the experience
required to fabricate the required bracket please contact Trio Avionics for guidance.
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.
If the screws need to be removed to reposition the crank arm, after repositioning,
Loctite
TM Number 222 must be reapplied (very sparingly) to prevent loosening of
the screws.
Choose an operating radius on the servo crank arm that allows full elevator movement
(elevator stop to elevator stop) without driving the servo crank arm into its limits. Most
aircraft get best performance in the outermost hole. In the event the servo rotation is
insufficient, the servo mechanical stops may be removed. Contact Trio Avionics if this
appears to be necessary.
6.2 Servo Mounting Hardware
Below is the provided electrical and mechanical installation kit. A pushrod is provided,
along with two rod end bearings. Typically, one of these connects to the servo crank arm
and the other is connected to the elevator bell crank. When the servo is connected to the
elevator 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 checks conducted after the installation is complete will verify proper
positioning.
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 EZ1 must be programmed to reverse the drive signal. In the event
unusual pitch changes occur in the first flight, the first check on the ground should
be to be certain the servo direction of travel is correct.