Dynon Avionics Capstan Servo (Cable-driven) - Manual (Page 3)

DYNON AVIONICS
Capstan Servo Kit – Installation Instructions 2
101385-000 Rev D
CAPSTAN SERVO KIT – INSTALLATION INSTRUCTIONS
Dynon Part # QTY Part Description
100976-011 4 AN365-1032A Lock Nuts
100977-000 8 AN970-3 Large Washers
100981-003 4 AN3H-6A Bolts - 3/4"
101056-000 4 Cable Clamps
101113-000 1 Bridle Cable Assembly
The capstan servo accessory kit includes the hardware necessary to attach one autopilot servo to one
axis of the aircraft controls. This kit can be used in either pitch or roll applications that utilize
pulley/cable driven controls (not suitable for use in pushrod linkage systems). Additional fasteners
(not supplied by Dynon) will be required to mount the servo in the aircraft.
When installing the servo, you must first determine a mount location for proper interaction with the
existing control system. This spot must allow the servo capstan to line up with the existing control
cables such that the provided bridle cable can be attached at each end using the nylon clamps and
ample room is available for the necessary motion of the system. The servo should also be mounted
as close to the control cable as possible to reduce the angle between it and the bridle cable, but not
so close as to rub during full range of control movement.
Once a suitable mounting location has been determined, the next step is to fabricate a bracket for
the servo. Refer to the included servo dimensions below. We recommend that 4 AN3H-3A bolts be
installed with MS35333-39 star washers (not provided). The 4 holes in the servo enclosure are fully
threaded to facilitate ease of mounting from the top, bottom, or a combination of both. If necessary,
removal of the capstan pulley and cable guard is permitted during fabrication of, and mounting into,
a bracket. Remove and discard the cotter pin and unscrew the castle nut. Remove the wave washer,
nylon washer, and finally the capstan pulley. Take care not to interfere with the installed shear
screw, as it cannot be removed without damage. The provided cable guard screws are long
enough to accommodate the cable guard being installed on top of a maximum of 1/16” bracket
material. More than this will push the heads of the screw up to an elevation that will interfere with
the reinstalled pulley. Do not reinstall with different screws as they may protrude into the
servo enclosure and damage internal components. If the drive cable is not parallel to the servo,
you may clock the cable guard to an orientation which allows the bridle cable to exit as required.
Torque the #6-32 cable guard screws back to 8 in-lbs and reinstall the rest of the parts as they were
removed. Torque the castle nut to 4.5 in-lbs, install and trim a new cotter pin.
Before final installation of the servo, assemble the capstan kit by removing the zip tie and unlooping
the bridle cable. Remove the heat shrink from both ends of the cable. Locate the swage nest hole in
the capstan pulley. The servo may need to be rotated to expose the hole if it is underneath one of
the flanges of the installed cable guard. Do not bend the flanges of the cable guard away from the
servo pulley; they are designed to keep the bridle cable from jumping grooves. Once the hole is
located, pass one end of the cable underneath one of the cable guard flanges so that the cable will sit