Trio Avionics EZ Pilot - v 2.3 - Manual (Page 32)

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mounting tabs will fit down over the screws. Nuts can be tightened down to secure it.
For a composite aircraft installation, the bottom of the plate (shown above) should be
floxed and the holes in the plate filled with flox before applying fiberglass layers over it to
secure it to the fiberglass structure.
Usually the servo pushrod will terminate on a control stick, a bellcrank, or perhaps a lever
sticking off of a torque tube. But in some cases (EZ’s for example) it is more convenient
to terminate on an aileron control pushrod, in which case care should be taken to keep
the pushrod from being free to rotate. (To repeat, the pushrod should NOT rotate.)
The reasoning for this is as follows:
If the servo pushrod will terminate on the aileron pushrod, the servo pushes or pulls on a
saddle bracket mounted on an aileron control pushrod, the attach point being offset
approximately an inch from the
centerline of the control pushrod. If
the two pushrods are not
perfectly aligned, the control
pushrod may rotate instead of
moving laterally. Rotating, instead
of moving, has the effect of putting
play, or slack, into the linkage and
will result in “hunting” while tracking.
The control movements are so
small that it takes very little slop in the system to make the airplane not track
properly.
It will simplify installation adjustments if there is enough overhead clearance to allow
removal and replacement of the servo lid with the servo remaining in place (for instance,
you will possibly want to adjust the slip clutch). The servo lid is secured by two screws on
the top of the lid.
7.4 Install the Servo Pushrod
Cut the pushrod to the proper length so that, when the servo is at neutral, the ailerons
are also neutral (see Note). Don’t worry about being exactly correct – the servo neutral
position will later be positioned (on the ground and in flight) using the electronics in the
EZ Pilot control head.
Choose the longest possible crank arm radius that accommodates a pushrod range of
movement equal to or exceeding that required for full aileron travel. Be sure that the
rod end bearings never jam due to misalignment as the pushrod angle is varied by
different combinations of control system input. Put the control stick (or control
wheel) in all four corners to test this.
7.5 Setting Servo Override Force (Slip Clutch)
The servo Torque Control nut (the locknut inside the servo on the output shaft) sets the
override force - the force you will feel at the stick when the servo clutch begins to slip.
Engage the servo by pressing the SERVO button on the control head. You should hear
the solenoid operate inside the servo housing and the servo crank arm should become
firmly held in place by the gear train. Then push the control stick hard enough to override
Note: The neutral position for your ailerons will be dependent upon how precisely your flying
surfaces are aligned. In many homebuilt airplanes, the ailerons must be trimmed for proper (hands
off) straight and level flight. It is important to test fly your airplane prior to installing the servo to
accurately judge the position of your ailerons in trimmed level flight. Remember this position – it is
the neutral position for your ailerons