Instructions Owner manual

DYNON AVIONICS

101156-000 - Rev D Page 1 of 3

Dynon Servo Shear Screw Replacement Instructions

In the event that a servo’s original shear screw loosens, becomes damaged or breaks, action

must be taken to service the screw. When followed properly, these instructions enable the

customer to perform this task in the field. If the customer does not feel comfortable

performing these actions, Dynon will be happy to inspect and/or repair servos as necessary.

Fig 1

A shear screw is “loose” if the screw is no longer firmly seated in the threaded servo

disc. This can be observed by holding the attachment disc completely still and

attempting to rotate the arm/capstan. No movement should be possible. If there is

any movement at all between these two parts, your shear screw is loose and should be

repaired per the following instructions. However, slight movement of the ENTIRE

arm/capstan/disc/shaft relative to the internal gearing is expected. This is inherent to

the design and due to designed-in drive gear lash and tolerance of the shaft captured

in the servo housing. Small amounts of movement here are normal and should not be

confused with a loose arm/capstan or shear screw.

1. Servo Arm

2. Flat washer

3. Wave washer

4. Castle nut

5. Cotter pin

6. Shear screw

PAGE 1
DYNON AVIONICS Dynon Servo Shear Screw Replacement Instructions In the event that a servo’s original shear screw loosens, becomes damaged or breaks, action must be taken to service the screw. When followed properly, these instructions enable the customer to perform this task in the field. If the customer does not feel comfortable performing these actions, Dynon will be happy to inspect and/or repair servos as necessary. 1. Servo Arm 2. Flat washer 3. Wave washer 4. Castle nut 5. Cotter pin 6.
PAGE 2
DYNON AVIONICS Care should always be taken when reworking the safety mechanisms on the servos. These features were specifically designed to fail under certain conditions. Deviation from these instructions could result in property damage, injury, or death. Removing Arm/Capstan To fully access the shear screw the arm/capstan must be removed. To do this, the cotter pin must be removed from the castellated nut. Note that cotter pins should never be reused; replace with a new pin.
PAGE 3
DYNON AVIONICS Never “re-torque” or “re-tighten” the shear screw while it is installed in the servo. After the threadlocker has started to cure, it MUST be removed and reinstalled with fresh threadlocker per the above instructions. If you are experiencing several shear screw breaks contact Dynon customer service immediately as this may be an indication of other installation issues. 1. Servo Arm 2. Flat washer 3. Wave washer 4. Castle nut 5.