SkyView System Installation Guide - Dynon Avionics

Autopilot Servo Installation, Configuration, and Calibrationcalled out maximum linear travel specification. If too much slippage occurs during servo flighttesting, it may be necessary to use a stronger servo.Each Dynon Avionics servo includes a precision-machined brass shear screw thatpins the servo arm to the servo arm attachment, providing an ultimate manualoverride. Servo shear screws will break at the application of 100 inch-pounds oftorque, at which point the servo arm will travel freely. If the brass shear screw isbroken during autopilot installation or usage, do not replace it with a standardscrew– contact Dynon Technical Support for a replacement shear screw.Instruction for replacing the shear screw can be found athttp://docs.dynonavionics.com.A broken shear screw indicates an abnormal condition in the installation and/oroperation of the autopilot and servo, much as a blown fuse or circuit breakerindicates a problem in the electrical system. Shear screws should be replaced withproper parts only after any problems are corrected.The servo shear screw should NEVER be removedor adjusted in the normal process of installing anautopilot servo. Instructions for both replacing abroken shear screw and instructions for changingor replacing the servo arm/capstan assembly canbe found at http://docs.dynonavionics.com.Figure 57 - Shear ScrewThere will be a variety of methods used to install the other end of this control linkage to theexisting mechanicals of the aircraft. Some systems will use a hole drilled into the bell crank asthe point where the servo push rod/rod end combination interfaces with the controls. Otherswill use an attachment to existing linkage. Others may attach directly to the control stick itself.It is up to the installer to decide which method is best in terms of safety and AP functionality.Installers should always keep in mind the range of motion of the servo. Total servo arm travelneeds to be limited to prevent an OVER CENTER condition (see caution note above), while stillpreserving the control surfaces’ full range of motion. Carefully consider the prevention of anover center condition when selecting the mounting location and linkage attachment point forany servo installation. The built-in control stops of the aircraft will limit the servo arm travelwhen installed correctly. Again, Dynon strongly recommends that the included Range of MotionLimiting Bracket be installed in order to absolutely prevent the possibility of an over centercondition. The Range of Motion Limiting Bracket should not be used as a normal stop; theaircraft’s built-in stops should always be the primary range limit. The Range of Motion LimitingBracket can be installed in different orientations depending on the aircraft geometry. However,it is important that it constrain the servo arm such that is unable to travel over center in eitherdirection. An example of how the Range of Motion Limiting Bracket can be installed isdemonstrated below. Use only the screws that are provided or specified in the Range of MotionLimiting Bracket Kit Installation Instructions (include with the Bracket Kit).SkyView System Installation Guide - Revision O 10-7