RPX Technologies DynaVibe GX Series User manual

DynaVibe GX Series User
Manual
Software Version 1.13
Revised: May 2017
Doc: RPX-AXU-RP-GX2-113-A
www.rpxtech.com

DynaVibe GX Series User Manual
Table of Contents
1Getting Started ___________________________________________________________ 2
1.1 Using this Manual ________________________________________________________2
2Background Concepts ______________________________________________________ 2
2.1 Dynamic Balancing _______________________________________________________2
2.2 Spectral Analysis _________________________________________________________2
3Applications _____________________________________________________________ 4
3.1 Propeller Balancing _______________________________________________________4
3.2 Rotorcraft Track and Balance _______________________________________________5
3.3 Vibration Spectral Analysis _________________________________________________6
3.4 Turbine Vibration Surveys __________________________________________________7
4DynaVibe GX Operation ____________________________________________________ 8
4.1 Ports and Connections_____________________________________________________8
4.2 Accelerometer Ports ______________________________________________________8
4.3 SD Card Slot _____________________________________________________________8
4.4 Optical Tach and Accessory Port _____________________________________________9
4.5 USB Port ________________________________________________________________9
4.6 Keypad _________________________________________________________________9
4.7 Turning on the System____________________________________________________10
4.8 Home Screen ___________________________________________________________10
4.9 Mode Summary _________________________________________________________12
5Mode Specifics __________________________________________________________ 14
5.1 Settings Mode __________________________________________________________14
5.2 Measure Mode _________________________________________________________15
5.3 EZ Measure Mode _______________________________________________________17
5.4 AutoBalance Mode ______________________________________________________22
5.5 Spectrum Mode _________________________________________________________32
5.6 TotalVibe Mode _________________________________________________________34
5.7 VibeSurvey Mode (GX3 Only) ______________________________________________35
5.8 Williams Mode (GX3 Only) ________________________________________________38
5.9 Rotorcraft (GX3 Only) ____________________________________________________45
6System Maintenance _____________________________________________________ 54
6.1 Cleaning _______________________________________________________________54
6.2 Battery Replacement_____________________________________________________54
7Troubleshooting _________________________________________________________ 55

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Copyright © 2017 RPX Technologies, Inc. Doc: RPX-AXU-RP-GX2-113-A
www.rpxtech.com Software Version: 1.13
Important Notice
Any system that distracts a pilot while operating an aircraft is a safety hazard.
During the balancing procedure, please use extreme caution. Be very careful
with cables and components, especially on pusher-type aircraft. ALWAYS
confirm the ignition is off before rotating the propeller, main rotor, or tail
rotor.
Areas of this manual will highlight some specific safety concerns while
operating the dynamic balancing system. Before using this system, review
and follow all safety instructions in this manual, the relevant application
note(s), and the aircraft manufacturer’s documentation.
This manual is for reference only and does not modify, replace, substitute for, or supersede official
regulations or the aircraft manufacturer’s instructions. There are risks and hazards associated with
modifications to aircraft and these modifications are potentially dangerous and could cause harm. RPX
Technologies, Inc. assumes no liability, either express or implied, in the use of this procedure.

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1Getting Started
1.1 Using this Manual
This document describes the general operation of the DynaVibe GX series of dynamic balancers
(including the GX2 and GX3). Some modes are only available on specific model variants and will be
marked accordingly, such as “GX3 Only”.
Because of the wide range of applications for this tool, use this manual in combination with one or
more DynaVibe application notes or aircraft maintenance manuals that describe the setup and usage
for specific applications.
2Background Concepts
2.1 Dynamic Balancing
A rotating mass will always have small imbalances and tolerance variations. On a fixed wing aircraft, for
example, the engine crank, spinner, propeller, propeller extension, and starter ring mass variations will
cause vibrations that propagate through the engine, airframe, instruments, and passengers.
Vibration can cause damage throughout the aircraft. For example, vibration can damage the crank
bearings, engine mounts, firewall, instrument panel, exhaust, air intake, and more. Vibration also
causes accelerated wear and fatigue on equipment and passengers. The negative effects of vibration
can be reduced by dynamically balancing the rotating assembly as a combined unit.
Dynamic balancing is accomplished by monitoring an accelerometer and an optical tachometer
attached to the aircraft. The dynamic balancer uses these sensors to monitor assembly movement,
rotational speed, and angular position as the assembly rotates. The balancer then quantifies the
vibration magnitude and phase angle. Based on this measured vibration magnitude and phase angle,
adding weight to the assembly at critical locations improves alignment of the center of mass to the
rotational axis, thereby reducing the vibration magnitude.
While not all vibration can be eliminated, any reduction in vibration will reduce physical damage and
passenger fatigue. Note that vibration from engine combustion, gear reductions, and accessories will
not be affected by dynamic balancing. These additional vibration components can be identified and
quantified using spectral analysis.
2.2 Spectral Analysis
Spectral analysis is a data processing technique that examines a broad range of frequencies
simultaneously. Unlike dynamic balancing, where the magnitude and phase of a single vibration

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Copyright © 2017 RPX Technologies, Inc. Doc: RPX-AXU-RP-GX2-113-A
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frequency are determined, spectral analysis displays vibration magnitudes of a broad range of
frequencies on a graph.
For example, in a fixed-wing piston-engine-driven aircraft, vibrations from engine misfire, prop
imbalance, prop wash, imbalanced alternator, etc. will each occur at a different frequency and will be
shown as individual peaks on the spectral graph. When performing spectral analysis with the optical
tach installed, the source of each vibration peak can often be identified by comparing the ratio of the
peak’s frequency to the frequency measured by the optical tach. On a non-geared four-stroke airplane
engine with a two-blade propeller, the propeller assembly vibration will be at 1x, weak cylinders will be
at 1/2 x, prop wash will be at 2x, etc.
Refer to the sections below for more information on how to use the DynaVibe GX for spectral analysis
and how it applies to your applications. RPX application notes, such as RPX-AFA-PR-SPC-00 "Spectral
Analysis of Piston Engine Aircraft," provide additional information.

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3Applications
3.1 Propeller Balancing
Process Overview
Balancing is an iterative process of vibration measurement and mass adjustments.
To balance a propeller, first mount an accelerometer to the engine and an optical tach to the aircraft as
described in the application note(s) listed below, or as described by the aircraft manufacturer’s
maintenance procedure. The DynaVibe GX uses these sensors to measure the vibration magnitude and
phase angle.Based on these measurements and information from previous runs, the balancer
determines the location where dynamic balance weights need to be added or removed to balance the
assembly.
DynaVibe GX Modes to Use
The DynaVibe GX has three modes useful for balancing propellers:
AutoBalance (recommended): This is the generally recommended mode for balancing propellers. Not
only does it report vibration magnitude and phase angle in an easy-to-understand format (zero degrees
is up and angles are always measured in the clockwise direction), this mode also recommends specific
mass adjustments and “learns” from each run. This simplifies and accelerates the balancing process.
When finished, the AutoBalance mode also generates a report for documentation.
EZ Measure: EZ Measure provides less automation than AutoBalance. While it does give vibration
magnitude and phase angle in the same easy-to-understand format, it does not recommend mass
adjustments. This mode is used to manually walk through the balancing process, compare front-to-
back vibration magnitudes, and other applications where a quick reading is needed.
Measure: Measure mode gives raw vibration magnitude and phase angle measurements from one or
two accelerometer channels. In Measure mode, the phase angle is not compensated for the setup (see
the Measure mode section below for how to interpret the phase angle). Measure mode is useful for
someone who has experience with a DynaVibe classic or another balancer that gives uncompensated
vibration phase angle readings.
Spectrum (troubleshooting):Note that while propeller assembly imbalance is the most common cause
of aircraft vibration, prop balancing only balances the propeller assembly. If vibration is still present
after the propeller is balanced, then spectral analysis can help identify the source of vibration. Refer to
the spectral analysis section below for more information.

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Application Notes and Procedures
This manual is not intended to be a comprehensive guide to propeller balancing. For process details
please refer to the following documents:
•Application Note: RPX-AFA-PR-BAL-00 “Dynamic Propeller Balancing on Aircraft”
•Aircraft manufacturer’s maintenance manual (if a procedure is available)
3.2 Rotorcraft Track and Balance
Process Overview
Rotocraft track and balance procedures vary by rotorcraft type and manufacturer recommendations.
General overviews are provided in this document and in our application notes, but please refer to the
manufacturer’s maintenance manuals for the exact track and balance procedure for your aircraft.
In general, main rotor track and balance procedures start on the ground with an initial dynamic balance
and blade track. Once an initial track and balance is complete, the process is repeated in a hover, then
in forward flight.
Other rotating components, such as fans, shafts, and tail rotors, can also be balanced using the
DynaVibe GX.
DynaVibe GX Modes to Use
Note: When using published track and balance charts or procedures from manufacturer’s
maintenance manuals, use only Rotorcraft mode or Measure mode since these charts and procedures
require raw phase angle readings.
Rotorcraft Mode (recommended):Rotorcraft mode in the DynaVibe GX3 can be used with or without
the DynaTrack. However, Rotorcraft mode is the ONLY mode that uses the DynaTrack for optical blade
tracking.Rotorcraft mode first helps you set up the system, then allows several measurement
conditions to be taken back-to-back, such as hover and multiple forward flight speeds. Blade track and
up to two vibration measurements (i.e. vertical and/or lateral) are recorded simultaneously during each
data set acquisition. This comprehensive set of measurements can then be used to determine what
adjustments are needed between flights to track and balance the ship.
Measure:Measure mode can be used to take single vibration measurements on a rotating component
using either one accelerometer alone or two accelerometers simultaneously. Please refer to the
Measure description above in the Propeller Balancing section, as well as the Measure mode
instructions below in the mode descriptions for more information.
AutoBalance (exercise additional caution when used with rotorcraft): Although AutoBalance mode is
intended for propeller balance applications, it can be useful when balancing other rotating components
on the helicopter such as tail rotors. Keep in mind that the initial weight addition recommended by
the AutoBalance mode should NOT be used on non-propeller applications because the weight
recommendations are based on typical fixed-wing propeller/engine mass and are not appropriate for

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other applications. Installing excessive weight may damage the assembly and the aircraft.The user
must estimate the first trial weight addition based on the particular assembly being balanced when
using AutoBalance mode for non-propeller applications. A common initial estimate for the trial weight
is 0.1% of the overall rotating mass (0.001 x mass).
Spectrum:Spectrum mode can be used to determine the source of various vibrations in the ship. Since
the main-rotor, tail-rotor, engine fan, engine, weak cylinders, prop wash (e.g., 2-per-rev on a two-
bladed propeller), etc. all occur at unique frequencies, spectral analysis can be used to identify the
source and magnitude of each component.
Application Notes and Procedures
This manual is not intended to be a comprehensive track and balancing guide. For process details
please refer to the following:
•Refer to the rotorcraft manufacturer’s maintenance manual for specific procedures!
•Application Notes: Several application notes are available to provide guidance unique to each
type of helicopter. Some examples include:
oRPX-ARA-RB-R22-TB “Robinson R22 Track and Balance with the GX3”
oRPX-ARA-RB-R44-TB “Robinson R44 Track and Balance with the GX3”
oRPX-ARA-BE-206-TB “Bell 206 Track and Balance with the GX3”
Covers: Bell 206A, 206B3, 206 L1/L3/L4, OH-58 A/C
o(refer to www.rpxtech.com for more rotorcraft-specific application notes)
3.3 Vibration Spectral Analysis
Process Overview
Spectral analysis, often referred to as an FFT, is performed with a single accelerometer and optional
optical tach. Spectral analysis of the accelerometer signal results in a magnitude versus frequency plot
of the vibration signal. When combined with an optical tach signal, these frequencies can be
conveniently compared to the rotational frequency of a reference component, such as rotor, propeller,
or engine RPM. Since many vibration sources have frequencies that are fixed ratios to a reference RPM,
the source of each vibration peak can usually be determined.
DynaVibe GX Modes to Use
Spectrum (recommended):Spectrum mode is used for most spectral analysis with the exception of
turbine engine vibration surveys, which require a wider frequency range.
TotalVibe (related): TotalVibe mode displays a graph of total vibration versus RPM. Although not a
spectral mode, TotalVibe is often useful in applications that require spectral analysis when vibration
magnitudes change significantly with RPM.

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Application Notes and Procedures
•Application Note: RPX-AFA-PR-SPC-00 “Spectral Analysis of Piston Engine Aircraft”
•Application Note: RPX-ARA-PR-SPC-00 “Spectral Analysis of Rotorcraft”
3.4 Turbine Vibration Surveys
Process Overview
Vibration surveys are used to help verify turbine engine health. By monitoring a wide range of
frequencies (up to 20 kHz) it is often possible to detect component balance issues, damaged bearings,
and other turbine engine faults.
GX Modes to Use
VibeSurvey (GX3 Only):The VibeSurvey mode measures the high frequencies required for turbine
vibration surveys. Note that the 20 kHz accelerometer (part number A20M0AS) and cable are required
for VibeSurvey mode. These parts are available in the “Vibration Survey Accessory Kit.”
Williams (GX3 Only):The Williams mode, like VibeSurvey mode, measures the high frequencies
required for turbine vibration surveys. However, Williams mode is customized for use with turbines
manufactured by Williams International and applicable procedures. Note that the 20 kHz
accelerometer (part number A20M0AS) and cable are required for Williams mode. These parts are
available in the “Vibration Survey Accessory Kit.”
Application Notes and Procedures
•Refer to the engine manufacturer’s procedure and/or maintenance program specifications for
procedures that are unique to each engine and maintenance program.