Dynon Avionics Servo User Manual

Autopilot Servo Installation Guide

Generic (Push-Pull)

This product is not approved for installation in type certificated aircraft

Document 101046-000, Revision F

January, 2013

Copyright © 2009-2013 by Dynon Avionics, Inc.

Permission to print this this manual is granted to third parties

DYNON AVIONICS

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Copyright

2008-2012 Dynon Avionics, Inc. All rights reserved. No part of this manual may be reproduced, copied, transmitted, disseminated or stored in
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Avionics products.

Servo Mounting Instructions – Generic Push-Pull Kit 1
101046-000 Rev E

DYNON AVIONICS

Kit Contents

Dynon Part #

QTY

Part Description

100836-000

2

Large Male Rod End

100982-006

1

Aluminum Tube - 8" (untapped)

100975-002

2

AN315-4R Jam Nut

100976-011

1

AN365-1032A Nylon Insert Lock Nut

100977-000

2

AN970-3 Large Flat Washer

100978-003

2

AN960-10 Small Flat Washer

100979-002

4

MS35333-39 #10 Internal Star Washer

100981-000

4

AN3H-3A Bolt - 3/8"

100981-005

1

AN3H-10A Bolt - 1"

SERVO MOUNTING INSTRUCTIONS – GENERIC PUSH-PULL KIT

The generic servo push-pull mounting kit includes some of the basic hardware to mount a servo and
connect to the aircraft controls. This kit can be used in either pitch or roll applications that use a
servo with an output arm (not suitable for use with pulley/cable servos). Some additional fasteners
(not supplied by Dynon) will be required depending on the installation method chosen.

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 arm and associated linkage to move freely
through the entire range of travel. To prevent the possibility of the servo arm going over center, the
servo arm must not travel more than a total of +/-60º from neutral throughout the control system's
range of travel.

Once a mounting location has been determined, the next step is to fabricate a mount for the servo
to attach to the aircraft. Generally this will be a bracket made of sheet metal or corner stock. We
recommend using 6061 T6 aluminum with a minimum thickness of 0.050” for the best balance of
strength to weight.

When fabricating a mounting bracket, refer to the included servo dimensions. Leave ample room for
the arm and attached linkage to move through a complete range of motion without interference. We
recommend that all 4 of the included AN3H-3A bolts be installed with the MS35333-39 star washers
and AN960-10 flat washers to secure the servo to a mounting bracket. All AN bolts supplied by
Dynon have drilled heads for use with safety wire. It is up to the installer to decide the attachment
method for mounting the bracket/servo to the aircraft.

Before the linkage can be installed, the included tube needs to be trimmed to length and tapped. 8"
of tubing is supplied, and a small amount of this tubing can be used as spacer(s) if needed. Spacers
can be used to reduce the offset angle between the servo end of the rod and the control system. The
inner diameter of this tube is 0.213"; this is the required diameter for both the #1/4-28 tap at both
ends of the push-pull rod, as well as for a #10 bolt through a trimmed spacer. Spacers used to
alleviate linkage angles should be limited to a maximum length of 1.0" to reduce excess flexing in the
control system.

Servo Mounting Instructions – Generic Push-Pull Kit 2
101046-000 Rev E

DYNON AVIONICS

Neglecting to properly install and/or use Dynon autopilot hardware may result in failures
which could cause loss of aircraft control resulting in aircraft damage, personal injury or
death.

When cutting the push-pull rod to size, take into account the extra length provided by the
unthreaded portion of each rod end. The distance between the servo arm and the control system
attachment point must allow for the angle between the servo arm and the push rod to be at
approximately 90º when the controls are at neutral. With the measurements taken, cut the tube
down to the correct length and tap both ends to a depth of 1" using a plug type tap. Once the push­pull rod has been cut and tapped, follow standard practices for threading both rod ends into the
tube with jam nuts installed. Thread the supplied AN315-4R jam nuts onto the rod ends. Screw at
least half of the threads on each rod end into the push rod. Adjust length as needed, and then
tighten jam nuts.

When using the generic mounting kit, we suggest first installing the linkage at the outer-most hole of
the servo arm. Changing this location will affect servo torque output, servo arm travel, control
surface resolution, and the amount of force required to shear the safety screw, and should only be
changed if the installer has an understanding of these implications. See the diagram on the following
page which illustrates the linear travel and available force for each mount point on the standard and
long-arm servos.

Standard mounting of the linkage to the servo arm will include the AN3H-10A bolt, AN970-3 large
diameter flat washer (for capturing the rod end bearing), 2 AN960-10 flat washers on each side of
the servo arm itself, and the AN365-1032A lock nut. If an alternate stack-up is required (which may
include a spacer trimmed from the supplied tubing), substitute the AN3H-10A with a longer bolt. It
is recommended that the rest of the stack-up remain the same, using the large diameter flat washer
as a safety device to capture the rod end bearing.

There will be a variety of methods used to install the other end of this control linkage to the existing
mechanicals of the aircraft. Some systems will use a bell crank that will need a hole drilled at an
appropriate location. Others will use an attachment to an 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 autopilot functionality.

Installers should always keep in mind the range of motion of the servo. Total servo arm travel needs
to be limited to prevent an over center situation. Take this into account when selecting the
mounting location and linkage attachment point for any servo installation. The built-in control stops
of the aircraft will limit the servo arm travel when installed correctly. We recommend you use the
optional Range of Motion Limiting Bracket, supplied with the servo to eliminate the chance of the
servo arm going over-center. This bracket should not be used as a normal stop; the aircraft’s built-in
stops should always be the primary range limit.

Your servo(s) and AP74/76 (if ordered) came with a CD containing the latest documentation for all
Dynon products (also available at dynonavionics.com). Please read through that documentation to
understand the wiring and configuration process for your Autopilot system. We also maintain a
collaborative set of this documentation, which is often updated with new information by both
Dynon and fellow builders. Visit wiki.dynonavionics.com to view and contribute to the latest
version of these documents.

You can also visit forum.dynonavionics.com to discuss and share installation notes, pictures, and
suggestions with other builders.

Servo Mounting Instructions – Generic Push-Pull Kit 3
101046-000 Rev E

DYNON AVIONICS

Red
Black
Green
Blue
Yellow
Wht/Grn
Wht/Blu

Servo 1

Wires

Pilot-accessible

Servo Power

Switch/Breaker

Aircraft GND

Red
Black
Green
Blue
Yellow
Wht/Grn
Wht/Blu

Servo 2

Wires

Aircraft GND

Aircraft Power (10-30V)

Pitch and Roll Servos

are wired identically, and can

share wiring for convenience at

any point along the run.

5 kohm

Optional resistor for

detecting broken

disengage lines

Pilot-accessible

Disengage/CWS button
(Normally open, momentary)
Usually mounted to the stick

Power (10-30V)
Ground
SkyView Network 1 A or DSAB A
SkyView Network 1 B or DSAB B
Disengage
SkyView Network Data 2 A *
SkyView Network Data 2 B *

Power (10-30V)
Ground
SkyView Network 1 A or DSAB A
SkyView Network 1 B or DSAB B
Disengage
SkyView Network Data 2 A *
SkyView Network Data 2 B *

Servo Current Draw at 12V
(halve the current values for 24V systems)

SV32
Powered but disengaged: 0.1 amps
Engaged and holding, 100% torque: 0.80 amps
Engaged and moving, 100% torque: 1.33 amps

SV42
Powered but disengaged: 0.1 amps
Engaged and holding, 100% torque: 1.11 amps
Engaged and moving, 100% torque: 2.03 amps

SV52
Powered but disengaged: 0.1 amps
Engaged and holding, 100% torque: 1.52 amps
Engaged and moving, 100% torque: 2.80 amps

Aircraft GND

Use 22 AWG wire for SkyNet

and Disengage signals.

Use appropriate wire gauge for

servo power based on current

consumption and length of wire run

Green

Blue

Twisted Pair

Twisted Pair

Twisted Pair

D10A/D100/D180

D25

CONNECTOR

SKYVIEW

D9

CONNECTOR

N/A
N/A

5
4

4
8
6
1

WHT/BLU

WHT/GRN

BLU

GRN

Wht/Grn

Wht/Blu

*NOT USED FOR D10A/D100/D180

Wiring Overview

The following diagram provides an overview of the autopilot-specific wiring installation. For the
complete set of wiring and configuration instructions, please see the latest Installation Guide for
your Dynon EFIS product. For a SkyView system please reference the Autopilot Servo
Installation, Configuration, and Calibration chapter of your SkyView System Installation guide.
For EFIS-D10A, EFIS-D100 or FlightDEK-D180 please reference the Autopilot Installation and
Configuration chapter of each respective Installation Guide.

Servo Mounting Instructions – Generic Push-Pull Kit 4
101046-000 Rev E

DYNON AVIONICS

Long-arm variants

(not needed in most

installations)have

linkage mount holes

at 1.5”, 1.75”, and

2.0”

L

Weight

SV32

2.17”

2 lb

SV42

3.10”

3 lb

SV52

4.02”

4 lb

Servo Dimensions

Use the following dimensions (in inches) for reference when planning and implementing your
installation.

Servo Mounting Instructions – Generic Push-Pull Kit 5
101046-000 Rev E

DYNON AVIONICS

Long Arm

Max Linear Travel
A: 3.4”, B: 3.0”, C: 2.6”

Max Force @ 100% Torque
SV32L - A: 18lb, B: 20lb, C: 24lb
SV42L - A: 27lb, B: 31lb, C: 36lb
SV52L - A: 36lb, B: 41lb, C: 48lb

Standard Arm

Max Linear Travel
A: 2.6”, B: 2.2”, C: 1.8”

Max Force @ 100% Torque
SV32 - A: 24lb, B: 29lb, C: 36lb
SV42 - A: 36lb, B: 44lb, C: 55lb
SV52 - A: 48lb, B: 58lb, C: 72lb

Linkage mount position force and travel

The two diagrams below illustrate the maximum travel and force available at each linkage mounting
point. As can be seen, the closer you mount the linkage to the shaft, the more force the servo can
deliver. However, this also means the travel of the arm is shorter. Again, ensure that the servo arm is
nowhere near going over-center throughout the entire range of the control system.

Servo Mounting Instructions – Generic Push-Pull Kit 6
101046-000 Rev E

DYNON AVIONICS

The autopilot safety shear screw should NEVER be removed or adjusted during this

operation. If the shear screw has broken and needs replacement, there is specific
documentation available for this purpose at http://docs.dynonavionics.com.

Servo Mounting Instructions – Generic Push-Pull Kit 7
101046-000 Rev E