Trio Avionics Wing Servo Mount Installation for RV-4 and RV-6 - Manual (Page 10)

The images at right are of the servo crank
arm (viewed through a mirror) with full left and
full right aileron deflection.
(Crank arm removed for clarity)
You MUST have a gap (clearance) at the servo “stops” when the ailerons are fully deflected.
A gap verifies the servo is not limiting the aileron travel. Equal gaps (between full left and
full right deflection) indicates the servo crank arm is in the mechanically neutral position. It
is not necessary for the gaps to be equal, only that gaps exist. Lengthening the servo push
tube (via the threaded rod ends) will increase the gap on one side and reduce it on the other.
The reverse is true when shortening the servo push tube.
Step 11:
Adjusting the push/pull tube. The linear movement of the servo push/pull tube
(from the neutral position) is not the same in both directions. (Van designed it this way.)
Therefore, the neutral position of the crank arm is NOT perpendicular to the wing spar when
the ailerons are pinned or clamped in neutral.
The installation kit has been designed so that, when installed properly, the servo bellcrank will
be very close to the proper neutral position when the push/pull tube is installed.