MicroVib II Aircraft Analyzer

FrontCover-1

MicroVib II Aircraft AnalyzerPN 1300

Users Manual PN 1318

Feb, 2014

Dynamic Solutions Systems Inc.2332 La Mirada Drive, Suite 100Vista, CA 92081Phone (760) 598-4000Fax (760) 598-4009Web www.dssmicro.com

1-91.15.1 Alphanumeric Data1-91.15 Entering Data1-91.14 Printing Data1-91.13.7 MicroBase1-81.13.6 File Types1-81.13.5 Navigating the File Directory1-81.13.4 Renaming Data Files1-81.13.3 Erasing Data Files1-81.13.2 Recalling Stored Data Files1-81.13.1 Saving Screen Image1-81.13 Working with Files1-71.12 Averaging Data1-61.11 Sensor Installation1-61.10.18 Init DSP Unit:1-61.10.17 Format (Erase) Disk.1-61.10.16 Analog Integration1-61.10.15 Set Max Input Signal1-61.10.14 Load (Import) Group1-61.10.13 Save (Export) Group1-51.10.12 Show Time Stamp1-51.10.11 Advanced Controls1-51.10.10 Set Input Parameters1-51.10.9 Frequency Scale in CPM (Hz)1-51.10.8 Create Group File1-51.10.7 New History File 1-51.10.6 Restore Factory Defaults1-51.10.5 Printing1-51.10.4 Set Date and Time1-41.10.3 System Parameters1-41.10.2 Set Owner Name1-41.10.1 Set LCD Contrast Level1-41.10 Control Panel1-41.9.3 Function Keys1-41.9.2 Arrow Keys, Backlight1-31.9.1 ON OFF Key1-31.9 Front Panel Keys1-31.8 Power On Self Test1-21.7 Battery Use and Care1-21.6 Customer Support1-21.5 Firmware Versions1-11.4 Equipment Lists1-11.3 How to Use This Manual1-11.2 Quick Start1-11.1 Introduction1-1Chapter 1 Basics

3-23.2.1 Cursor Modes3-13.2 Function Keys3-13.1 On Screen Data3-1Chapter 3 Spectrum Mode

2-152.12 Helicopter Track & Balance2-142.11.3 Estimating Sensitivity Factor2-142.11.2 Estimating Tach Offset (Props)2-132.11.1 Propeller-Rotor Protractor2-132.11 Reference Information2-132.10.5 Editing Group Files2-122.10.4 Printing Out the Group File2-122.10.3 Saving A Group File2-122.10.2 Templates2-112.10.1 Creating a Group File2-112.10 Group Files2-102.9 Task Functions2-102.8.6 Evaluating History Data2-102.8.5 New History File2-102.8.4 Clear History2-92.8.2 Default History Files2-92.8.1 View History2-92.8 History File2-92.7 Weighing Procedures2-82.6.1 Generic Balance Procedure2-82.6 Balancing Procedure2-62.5 Weight Computer Procedures2-62.4.4 Add Weight2-62.4.3 New Radius2-62.4.2 Split Weight2-62.4.1 Enter Weight2-62.4 Weight Computer2-42.3.2 Solution Function Keys2-42.3.1 Solution Screen Data 2-42.3 The Balance Solution Screen2-22.2.1 Balance Options2-22.2 Balance Function Keys2-12.1 On Screen Data2-1Chapter 2 Balance Mode

1-101.19 Auto Shutoff1-101.18 Field Cal Check1-101.17.1 Cal Flag1-101.17 Calibration1-101.16 MODE Screen1-101.15.2 Numerical Values

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7-47.6 Notes7-37.5 Tracking Procedure7-37.4.3 Equipment Hookup7-37.4.2 Azimuth Location7-37.4.1 Tach Signal 7-37.4 Equipment Setup7-37.3.3 Metric Units7-37.3.2 Double Images7-37.3.1 Number of Blades7-37.3 Track Options7-27.2 Function Keys7-17. 1 On Screen Data7-1Chapter 7 Strobe Tracking6-76.6 Tracker Configurations6-66.5 Tracking Procedure6-46.4.4 Aiming the Tracker6-46.4.3 Background6-36.4.2 Adequate Light Level 6-36.4.1 Tach Signal 6-36.4 Equipment Setup6-36.3.5 Metric Units6-36.3.4 Set Number of Revs6-36.3.3 Set Track Distance 6-36.3.2 Display Lead Lag6-36.3.1 Number of Blades6-36.3 Track Options6-26.2 Function Keys6-16. 1 On Screen Data6-1Chapter 6 Optical Tracking5-15.3 Tach Options5-15.2 Function Keys5-15.1 On Screen Data 5-1Chapter 5 Tach Ratio4-24.3 Waveform Options4-14.2 Function Keys4-14.1 On Screen Data4-1Chapter 4 Waveform Mode3-53.4 Spectrum Procedures 3-43.3.7 10 Hz High Pass Filter3-43.3.6 Show Overall3-33.3.5 Flat Top, Hann or Rect Window. 3-33.3.3 Display Units & Units Type3-33.3 Spectrum Options

A-5-2WarrantyA-5-1TroubleshootingA-4-1Customizing Group filesA-3-2Signal SimulatorA-3-1Multiplex UnitsA-2-1Charge Amplifier PN 1498A-1-4Cable Hookup DiagramsA-1-3Connector PinoutsA-1-1Specifications

8-28.2 True RMS Scan8-18.2 True Peak Hold8-18.1 Overall Scan 8-1Chapter 8 Scan Modes

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Chapter 1 Basics1.1 IntroductionAt first glance, this manual might overwhelm thenew user with the sheer number of functions andchoices available with the MicroVib II Analyzer.Don't despair, all of the standard choices havealready been made for you in the "as received"condition of the unit. All the new user will have todo to begin using a new MicroVib II is to pick theunit up and use it. These choices that are alreadymade for you are referred to as the "FactoryDefault" setup. In the event that you change theunit's setup parameters and wish to restore theFactory Defaults, this setup can be quickly recalledin the control panel.

This unit contains many functions that you maynever use. If you find that you only use 10 or 20 percent of the features of the unit, don't worry, thisis entirely normal. Modern technology allows us topack tremendous power and functionality into thiscompact unit without detracting from it's ability toperform the function you need.

If you have used any modern computer programlike a word processor or spreadsheet, you knowthat the program has hundreds of features andcapabilities you may "never" use. The fact thatthese additional features exist should not get in theway of using the tool. They are there should youever need them.

1.2 Quick StartIf you need to use the MicroVib II immediately,you may need an application note for the aircraftyou are working. Generic procedures can be foundin Chapters 2 and 3, but if an app note exists foryour type of aircraft, it can save some time. AppNotes are avaliable on-line to customers.

1.3 How to Use This ManualChapter 1 provides information about the basicfeatures common to all modes of operation.Equipment lists, Battery care, Power on self test,Saving, Recalling and Deleting files, Enteringnumbers and letters and Printing.

Chapter 2 Balance Mode Chapter 3 Spectrum ModeChapter 4 Waveform Mode Chapter 5 Tach Ratio Mode Chapter 6 Optical Tracking Mode.Chapter 7 Strobe Tracking ModeChapter 8 Scan Modes

1.4 Equipment ListsUnpack the Analyzer and compare the contents ofthe package with your shipping invoice. A list ofstandard and optional items follows.

Standard Equipment

PN Description1300 MicroVib II Aircraft Analyzer1460-3 Accelerometer, Top Exit 1008-1 Accelerometer bracket, .25 Hole1008-2 Accelerometer bracket, .31 Hole1015 Photo Tach 1520 Photo sensor bracket1254 Reflective tape (1 roll)1377 Electronic Gram Scale1010 Prop/Rotor Protractor1309 Battery Charger 120/240 Vac 1341 Charger Power Cord 120Vac1311 Serial Interface Cable 9 pin1600 MicroBase Pro Software1318 MicroVib II Operation Manual

Prop Balance Accessories

1310 Case, Single/Dual Prop Balance1007 Cable Set Single Prop Balance1880 Accelerometer, Side Exit

Helicopter/Multi-Engine Accessories

1096-15 Accelerometer Cable Assy, 15 ft.1096-50 Accelerometer Cable Assy, 50 ft.1097-50 Photo Tach Cable Assy, 50 ft.1450 Mux Unit, 4x4 for Optical Tracker1145-5 Optical Tracker1990 Carrying Case, Large1131 Breakout Cable Acc-Tach

Strobe Tracking Accessories

1680 Mux Unit, 4x4 for Strobe1123 DC Power Cable, Strobe Mux

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Other Accessories

1560 Mux Unit A+B, A-B1062 Hardware Kit with Case1507 Hi Temp Accel Cable 10 ft.1498 Hi Temp Charge Amplifier1500 Hi Temp Accel, Hi-Temp1106 Balance Simulator1117-2 Signal Simulator Acc-Tach1147-1 MicroTach1170 Mag Pickup Cable1176 Mag Pickup1216 Gaffer's Tape1280 Signal Simulator Tracker-Tach1426 Charger Cord Euro1635 Charger Cord UK1725 Charger Cord Aus/NZ

1.5 Firmware VersionsDSS is continually improving the MicroVib II viaEPROM upgrades. The firmware version numbercan be seen on the right center area of the LCDdisplay when the unit is powered up and goesthrough it's normal power on self test function.

This manual describes version 1.33, 1.34, & 1.35 ofthe firmware. As eprom upgrades are made, manualrevisions will be made. If you would likeinformation regarding the current productionfirmware available as an upgrade to your MicroVibII, please contact us.

1.6 Customer SupportIf you should find a discrepancy in your kit or havea technical problem, contact DSS as follows:

Corporate Headquarters - Sales/Engineering (760) 598-4000 Fax: (760) 598-4009

Email Sales: [email protected].

Email Support: [email protected]

Software/Applications Engineering (714)898-7087 Fax: (509) 6963436

Email Applications:[email protected]

1.7 Battery Use and CareA NiMH rechargeable battery pack is used topower the Microvib II. Before starting a task, verify that the battery has enough charge to operateproperly.

The battery needs to be recharged if:

The analyzer will not power up

The analyzer displays a low battery warningand turns off.

The battery bargraph indicator shows lessthan 10% capacity.

Note: Longest battery life is achieved ifthe battery is allowed to run down to10% before recharging .

Battery Self-Discharge

The battery will self-discharge even with no use ata rate of about 4% per week at 70F (10% per weekat 113F). This is normal and should not be ofconcern. During times of little usage, recharge thebattery about once every 3 months for best results.

Checking the Battery

The Battery level is displayed in all measurementmodes as a battery shaped icon with bargraph in theupper right portion of the LCD display. The batteryvoltage is displayed along with a bargraph thatprovides a 0-100% relative indication of batterycharge status.

This bargraph will normally give a good indicationof battery status, but it can be misleading undercertain conditions. It will be misleading for the first15-30 minutes after a change of charge state hasoccurred. For example, if the battery is on thecharger and has been charging for the last ½ hour,you can turn the unit on and get a good idea of thecharge status. But if you unplug the charger, this isa change of state and the readings will be way off(high) for about ½ hour. Conversely if the unit hasnot been on charge for at least ½ hour, the bargraphreadings will be correct, but if you plug in thecharger, the readings will be way low for about ½hour.

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When the battery charge drops below 0%, theanalyzer will display “Low Battery Shutdown” andturn itself off. There is no risk of data loss whenthis occurs, as the memory in the MicroVib II isnonvolatile and does not require battery power toremain intact. The collected data are retained inmemory and can be accessed after the analyzer isconnected to the charger. The charger will provideenough power to operate the MicroVib II andcharge the battery at the same time.

Battery Charging

To recharge the battery, plug the charger into90-250V 50/60Hz AC mains power, and then plugthe charger into the battery charger input located onthe right end of the unit. The LED next to thecharger jack on the unit will light up indicating fastcharging has begun. The supplied battery chargerwill completely recharge a fully discharged batterypack in about 4 hours. We recommend you waituntil the battery capacity is below 20% and thenput the battery on the charger at the end of the dayand allow it to charge. The fast charge willautomatically terminate in about 3-4 hours. TheLED will go off when the battery is fully charged,but the charger will continue to trickle charge thebattery indefinitely. It is due to this “trickle charge”that we do not recommend leaving the battery onthe charger continuosly.

Longest battery life will be achieved if the chargeris used sparingly. NiMH batteries do not have a"memory", but trickle charging a fully chargedbattery does reduce its life.

The MicroVib II, with a charged battery, willoperate for approximately 18-24 hours of normaluse. The exact operational time will varydepending on the operations being performed,photocell use, LCD backlight use, etc.

Battery Life

The battery is rated to last for 500-1000 completecharge discharge cycles. The first symptoms ofbattery end of life will be premature chargetermination. This is an indication the battery maysoon fail to work entirely. We recommendreplacing the battery pack when you notice the

pack did not re-charge fully and as a result onlylasts a very short time after charging.

Changing the NiMH Battery

We do not recommend the user attempt to replacethe battery. During normal annual calibration, DSSwill perform a test and replace the battery if it is ator near the end of life.

1.8 Power On Self TestTo turn the MicroVib II on, press the ON OFFkey. When turned on, the unit will perform poweron self test and then begin operating the last modeused when power was turned off.

Self test performs the following checks:

1. Battery is checked for voltage in range

2. LCD Processor is checked

3. RAM is checked.

4. Disk (Flash) is checked

5. I/O System is checked

6. CPU Processor is checked

7. DSP Processor is checked

8. Externally connected equipment is checked.

9. Serial Number is displayed

10. Firmware version is displayed

11. Time and Date is displayed.

1.9 Front Panel KeysFollowing are brief descriptions of the functionkeys on the front panel of the unit.

1.9.1 ON OFF Key

1. When the analyzer is off, pressing the ONOFF key briefly will turn the unit on and willinitiate the power on self test function, leadingto normal operation.

2. When the analyzer is on, pressing the ON OFFkey down and holding it down for 1 secondwill turn the analyzer off. The screen willbriefly display “MicroVib II User Requested

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Shutdown” during turnoff. This delay allowsthe unit to close all files and shut downproperly without losing any data.

3. When the analyzer is off, pressing the ONOFF key down and holding it down for 8seconds and then releasing the key willperform a cold boot. This will create a newbalance history and restore factory defaults.

Note: If the unit will not turn on, thebattery may be fully discharged. Plug inthe charger and wait one minute and tryagain

1.9.2 Arrow Keys, Backlight

The four Arrow keys have several functions:

1. The primary function of the arrow keys is tomove the cursor around the screen to highlightvarious graphical elements like spectral peaksin the Spectrum mode.

2. Simultaneously pressing the left and rightarrow keys will turn on the backlight. Doing itagain will turn it off. The backlight is notvisible in normal room light, so don’t use thebacklight unless it is hard to read the displaydue to very low lighting.

3. When entering numeric data, the down arrowkey serves as a minus sign key.

1.9.3 Function Keys

The twelve function keys on the sides of the LCDscreen perform the function described on the screennext to the key. In each operating mode, any actionyou can perform will be available on these keys.

1.10 Control PanelThe Control panel menu contains functions thatdefine and control the operation of the analyzer. Toaccess the control panel: Press the MODE key,then press the CONTROL PANEL key.

1.10.1 Set LCD Contrast Level

Press the Right Arrow key to darken the screen andpress the Left Arrow key to lighten the screen. Abar graph will indicate the current value of LCDcontrast from 0-100%. The RIGHT and LEFTarrow keys act as a coarse adjust. The UP andDOWN arrow keys act as a fine adjust.. The LCDcontrast is temperature compensated, so itshouldn’t change very much as the unit gets hot orcold.

1.10.2 Set Owner Name

Normally this name has already been entered andthis selection is not available, but if it is shown,you can press this key and enter the owners name.Be sure to carefully check the spelling and titlebefore pressing this key, as once entered, this valuecannot be changed except by the factory. If youaccidentally go into this screen, just turn the unitoff and the owner name will be left blank

1.10.3 System Parameters

The system parameters screen provides someimportant information about the unit. It displays theOwner Name, Unit Serial Number, Firmwareversion, System RAM size, Micro-Disk (Flash)size, Real Time Clock Time and Date, Lastcalibration date, Total time since new, Total timesince last calibration, and Battery voltage. Version1.34 & 1.35 add a countdown timer to auto-shutoff.

The bottom line on the screen is a live display ofthe type of peripheral that is connected to the unit.You can connect and disconnect peripherals whilewatching this display and it will immediatelyidentify and display the peripheral that is attached

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1.10.4 Set Date and Time

Press the SET DATE AND TIME key to set theYear, Month, Day, Hour, Minute and Second. Alldata captured by the unit will be tagged with thisinformation, so it is important to set it properly.The time is in 24 hour (military) format. The unitwill be factory preset to the current time at thefactory in California, but you will want to change itto your local time. Once set, the clock will run onthe very small internal 3V Lithium battery, whichis independent of the large NIMH battery pack. TheLithium battery is designed to run the clock for atleast 10 years. The Lithium battery is soldered tothe PC board.

Note: If you set the time a little bitahead and then monitor your watch, youcan press the OK key when the time isexactly right and the clock will be insync with your watch (or computer clocketc.).

1.10.5 Printing

The MicroVib II can print by downloading yourdata to a PC and using MicroBase to print via yourPC printer.

1.10.6 Restore Factory Defaults

Pressing this key will reset all system settings likeMode, RPM range, Sample Rate etc to their factorydefault settings. When this is done, one moreselection is displayed. RESTORE INPUTDEFAULTS will reset the sensor type, sensorsensitivity, and ICP power on/off settings for allinputs to the factory defaults.

1.10.7 New History File

When you are finished with the current history fileand want to start fresh with a new file, this keysaves the current history file and opens a new file.This will lead to a screen where you are asked toselect a template or group file. See section 2.10 formore on templates and group files.

1.10.8 Create Group File

If the group files or templates listed do not coveryour application, you can create a new group file

based on an existing group file or template usingthis key. See section 2.10.1.

1.10.9 Frequency Scale in CPM (Hz)

Press the FREQUENCY SCALE IN CPM key tochange the frequency scale in all modes to Hz.When this key is dark, units are CPM, when thekey is light, units are in Hz. This key is a toggle.CPM means cycles per minute and Hz meanscycles per second.

1.10.10 Set Input Parameters

To choose the type of sensor, sensitivity, andsensor power, press this key. You can enterdifferent parameters for each of the 16 possiblechannels. The default values are Accelerometer,20mv/g, ICP sensor power ON.

1.10.11 Advanced Controls

By pressing the ADVANCED CONTROLS key,you get access to several more optional settings:

1.10.12 Show Time Stamp

This option disables the date and time display onall analysis screens. Default is on.

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1.10.13 Save (Export) Group

After you have created a new group file in thecurrent history, you can save this group file byitself on the disk. You will be prompted to namethe group file.

1.10.14 Load (Import) Group

If you selected the wrong group file when you firstcreated the current history file, you can delete thecurrent group and load another group file from thedisk into the current history with this function. Wedo not recommend this after any data has beensaved in the current history.

1.10.15 Set Max Input Signal

Pressing this key allows you to disable the autorange function and set the unit to fixed gain mode.The desired full scale range of the display can beentered. If a value over the spec limit is entered, theunit will set the level to the maximum allowable. Ifa value less than the minimum level is entered, theminimum will be used. The unit will automaticallychoose the lowest input signal range that includesthe display range. This key will be dark if a fixedgain setting has been entered. To return to normalauto range mode, enter a full scale value of 0 orpress the RESTORE FACTORY DEFAULTSkey.

1.10.16 Analog Integration

This key enables and disables analog or digitalintegration when converting acceleration units tovelocity units and then in turn to displacementunits. Default is analog integration (key dark).

1.10.17 Format (Erase) Disk.

This option allows you to erase all the data that hasaccumulated on the nonvolatile disk (Flashmemory). This does not erase calibration data.

1.10.18 Init DSP Unit:

This option allows you to initialize the DSP unit.This is not required for normal use.

1.11 Sensor InstallationInstalling The Vibration Sensor

The vibration sensor should be mounted securely tothe aircraft near the target rotor, prop or engine.Find an appropriate location and attach the bracketPN 1008-1 or 1008-2 to the aircraft. Mount PN1880 or 1460-2 Accelerometer to it using thecaptive bolt on the bracket. Tighten the bolt toapprox. 6-8 ft-lb torque. The sensor sensitive axismust be mounted in the plane perpendicular to therotation axis, but it can be mounted in anyconvenient orientation. Up or down at 3, 6, 9 or 12o’clock, all will work fine.

If manufacturer procedures or application notesalready exist for the subject aircraft it is stronglyrecommended that those procedures be followed.

Installing a Magnetic Pickup

Many aircraft come from the factory withprovisions (bracketry) for mounting a magneticpickup and interrupter. The magnetic pickup isinstalled securely near a rotating component likethe swashplate or spinner. A ferrous metal object(interrupter) must pass very close to the tip of themagnetic pickup to generate a usable signal. Thisfunction is usually provided by a small metalbracket attached to the rotating part of the rotor.Use PN 1176 Magnetic Pickup and PN 1170 MagP/U cable. The rotor must have only one interrupterto be compatible with the Microvib II.

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Installing the Photo Sensor

The photo tach is mounted securely to the aircraftand aimed at the rotor/blade path. A patch ofreflective tape is applied to a blade to intercept thephoto tach beam. The reflective tape must intersectthe photo tach beam for at least 300 microseconds.The minimum tape length may be computed usingthe following formula:

Tape length = (Radius(in)xRPM)/20,000

Note: The older retro-tape PN 1014was very hard to remove. The newer typeof tape PN 1254 is easy to remove.

Connecting the Sensors

Connect the Accelerometer and Photosensor to theMicroVib II using either PN 1007 Cable Set or PN1096 & 1097 Cables and MUX Unit, or PN 1096 &1097 Cables and PN 1131 Breakout Cable. Each ofthese options includes an 18 pin MS Bayonet typeplug that mates to the MicroVib II.

Secure the Cables

Be sure to route and secure the cables to preventthem from touching any hot surfaces or interferingwith any control lines. If the cable is in the path ofany strong air flow, secure it so it cannot bangagainst any painted surface and cause damage.

1.12 Averaging DataPressing the AVG DATA key during ameasurement enables or disables the averaging ofdata. It is important to verify that the RPM is stablebefore averaging is started.

Spectrum Averaging

In the default averaging mode, the Microvib II willcomplete four averages and then update thedisplay. The analyzer will then immediately start anew set of averages. In between these updates, thelast averaged spectrum is displayed.

The number of averages is shown at the bottom ofthe screen slightly left of center. You can changethe number of averages, type of averaging, or peakhold display from the SPEC OPTS (SpectrumOptions) screen, which is an option on theSpectrum Analysis screen.

Waveform

Averaging is not available in this mode.

Balance Mode Averaging

Using the BAL OPTS (Balance Options) screen,the averaging used in balance mode can be set tolinear (default) or exponential.

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6 in12 in

18 in

1.81.2.6

Minimum Retro-tape length at 2000 RPM.

Radius

Linear Averaging

Linear averaging is very simple: Each successivemeasurement is added and the result is divided bythe number of measurements. In this mode veryerratic data will usually average out to a verysteady result. This is the mode recommended forreciprocating engine propeller work or any otherapplication which produces unsteady vibrationreadings. The recommended number of times toaverage the data is 8 in balance mode.

Exponential Averaging

Exponential averaging places more weight on themost recent measurements compared to the oldermeasurements. In this way a feel for how the datais changing is retained no matter how long the datais averaged. This mode will greatly reduce the largejumps of erratic data, but will not get progressivelysmoother with time as with linear averaging.

1.13 Working with FilesAny display from an analysis mode (balance,spectrum, waveform, track or tach ratio) can bestored in the analyzer's disk and recalled later forviewing or printing. History files can also be savedor recalled.

1.13.1 Saving Screen Image

To store a screen, press the SAVE PLOT key. Youwill be prompted to give the data item a file name.You can enter a name or you can let the unitautomatically assign the name. The default namewill be on the screen, but you can type over it. (Forinstructions on how to enter data into analphanumeric menu, see "Entering Data" in section1.15.)

Press the OK key to store the data. After the itemhas been stored, the screen will display the saveddata in the Hold mode. You may resume analysisby pressing the START STOP key.

1.13.2 Recalling Stored Data Files

To recall stored data from the analyzer's memory,from any analysis screen press the FILE key toaccess the File directory. Use the UP and DOWNARROW keys to highlight the desired data file andpress the OPEN FILE key; the analyzer will then

display the selected data. All appropriate functionkeys and cursor controls are available tomanipulate the recalled record.

When a stored data file is selected for display, thecurrent user settings are temporarily stored. Thesettings that were active when the recalled recordwas saved are in effect while that file is beingviewed. The current settings will be restored afterexiting the file.

1.13.3 Erasing Data Files

The File directory screen, obtained by pressing theFILE key, can also be used to erase files from thedisk. Use the UP and DOWN ARROW keys tohighlight the desired data file and press theERASE FILE key; the analyzer will then erase theselected file. To erase all files, see section 1.10.17.

1.13.4 Renaming Data Files

The File directory screen, obtained by pressing theFILE key from any analysis screen, can be used torename files on the disk. Use the UP and DOWNARROW keys to highlight the desired data file andpress the RENAME FILE key; the analyzer willthen prompt you to give the file a new name. Enterthe new name and press OK.

1.13.5 Navigating the File Directory

Since files are kept on disk indefinitely, the file listmay become quite long. It may span many screensof file names. You can use the NEXT PAGE andPREV PAGE keys in the file directory screen toquickly move through a long list

1.13.6 File Types

Several different types of files are used:.

History Files (Suffix HST) Each history file cancontain data from up to 10 tasks. Task details are asdefined in the group file contained in each historyfile. The history file is limited to 64 balance runs.

Spectrum Plot Files (Suffix SPC). Spectrum filesare saved in this format. The amount of space usedon the disk will be a function of the number oflines.

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Waveform Plot Files (Suffix WAV) Waveform plotfiles are saved in this format. The size of the wavefile is a function of the number of points.

Balance Plot Files (Suffix PKP) The balance screencan be saved in this format. This will not normallybe used as this data is saved in the history filealready.

Track Plot Files (Suffix TRK) Track data is savedin this format. Track data will be annotated withthe task and time for later identification.

Tach Plot Files (Suffix TAC) Tach Ratio scans aresaved in this format.

Group Files (Suffix GRP) Every history filecontains a group file, but the group file can besaved separately and used for new history files.Group files are a collection of tasks along with thedetails about each task.

1.13.7 MicroBase

MicroBase is a database program that runs on yourPC using the Windows operating system. Itprovides a means of storing and organizing all thedata you collect with the Microvib II. It also allowsyou to print your data using your computer printer.It also provides a means of sharing data with DSS,Aircraft manufacturers and other users. MicroBasecomes with a powerful help system that serves asits user manual .

1.14 Printing DataThe MicroVib II prints by downloading your datato the MicroBase program running on a WindowsPC, then printing to your computer printer.

1.15 Entering Data1.15.1 Alphanumeric Data

Some display screens of the MicroVib II allow youto enter alphanumeric characters; for example: togive a file a name other than the automaticallyassigned name.

To enter a character, repeatedly press a key to stepthrough its assigned characters (for example A B CD E F) until the desired character is displayed. Thecursor will then automatically advance to the nextspace after a one second pause or after another keyhas been pressed. Numbers from zero through ninecan be entered in a similar manner.

The Left Arrow key may be used to backspace thecursor, and the Right Arrow key may be used toadvance the cursor through the field. The ADDCHR key inserts a blank at the current cursorlocation and shifts the remaining right sidecharacters to the right. The DEL CHR key deletesthe character at the current cursor location andshifts the remaining right side characters to the left.The CLR CHR key deletes the character at thecurrent cursor position and leaves the space blank.The CLR ALL key deletes the entire string shown.Press the OK key to accept the text shown andreturn to the previous screen.

Special Characters

The only special characters shown on function keysare ^ _ ` ! # & ( ) - There are 4 more specialcharacters available $ % ’ @. To enter thesecharacters, use the up and down arrow keys and thecharacter at the cursor location will scroll thru allthe available characters, including these specialcharacters.

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1.15.2 Numerical Values

Many functions of the unit require you to enternumbers. When this is required a screen will appearwhere each function key is labeled with a number.To enter a number like 125, just press the 1, 2 and5 keys in that order. Enter decimal points asrequired. The Right and Left arrow keys can beused to edit any errors you might have made. Justmove the cursor to the errant digit and type in thecorrect value. The Up and Down arrow keys willchange the sign of the number. When you arecertain the value is correct, press the OK key.

1.16 MODE ScreenThe primary menu screen is the MODE screentitled Select Operating Mode. From this screen youcan select one of the six analysis modes or thecontrol panel.

Press the appropriate menu item key to select oneof the following modes.

Spectrum Analysis - Measures the Vibrationvs. Frequency signature produced by thesensor currently selected.

Waveform Analysis - Measures theVibration vs. Time signature produced by thesensor currently selected.

Scan Modes - Provide a simple overall valueof the vibration at the sensor.

Control Panel - Provides a means to controlthe various optional settings used to operatethe unit..

Tach Ratio Display - Measures the rate ofthe incoming tach signal and displays itrelative to %RPM values specified.

Prop/Rotor Balance - A system forbalancing all kinds of rotors and props usingvibration and tach sensors.

Rotor Blade Tracking - A system formeasuring the visual track of any helicopterrotor system. Either the DSS Optical BladeTracker or a compatible strobe light can beused.

1.17 CalibrationDSS recommends the MicroVib II be calibratedonce per year at a factory certified calibrationfacility. If no such facility is available near you,return the unit to DSS for annual calibration.Calibration normally includes updating firmware tomost current version and any necessary hardwareupgrades.

1.17.1 Cal Flag

1 year after calibration, the MicroVib II will showa “NO CAL” flag on the screen. This is just areminder to have the unit calibrated. It has no effecton the instrument accuracy. When the unit iscalibrated, this flag is reset.

1.18 Field Cal CheckUsing the Signal Simulator PN 1117-2 you canperform a quick cal check to be sure yourMicroVib II is reading correctly.

Procedure:

1. Turn unit on, Press MODE, CONTROL PANEL,RESTORE FACTORY DEFAULTS, RESTOREINPUT DEFAULTS, DONE, DONE, START.

2. Connect the Signal Simulator. The vibrationlevel should read between .765 and .845 IN/S. Thephase reading should be between 270 and 274degrees. The Tach reading should be between1919.5 and 1920.5 RPM.

If your unit does not read properly, repeat theabove procedure to be sure and then return the unitto DSS for calibration.

1.19 Auto ShutoffTo maximize battery life, the unit shuts itself offafter 5 minutes with no user key presses (V1.33)Firmware versions 1.34&1.35 added the ability tocontrol this auto-shutoff delay from 1 to 60minutes. This feature is accessed from the ControlPanel by pressing Advanced Options, Set Auto Off.

Chapter 1 Basics

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Chapter 2 Balance Mode This mode is used for balancing rotors andpropellers. It requires a tach sensor (photocell ormag pickup) as well as a vibration sensor(accelerometer) mounted near the target rotor inorder to function. See Section 2.6 for procedure.

To access the balance mode from any analysisscreen, press the MODE key, press the Prop/RotorBalance Key, and press Start Analysis.

2.1 On Screen DataThe Balance mode provides the following data onscreen.

1. Polar Plot of Vibration Data: Dominatingthe screen is a large polar plot of the vibrationlevel and the phase angle of the vibrationrelative to the tach signal. This data willupdate sample by sample in real time.

2. Task Name: The current task name isdisplayed. This name is user definable. Seetask setup to name the task.

3. Sensor Channels: the current sensor channelsare indicated. If a single accelerometer andtach sensor are connected, this will indicateCH: 1A. But if a MUX type unit is connected,

this will indicate which of the sensors havebeen selected for the current task. (See 2.9.1)

4. Signal level bargraph: In the upper leftcorner is a bargraph display that indicates thecurrent full scale range selected by the autorange function, and the level of the incomingsignal as a percentage of that range.

5. Vibration Amplitude: A digital readout ofthe current vibration level at the tach rate is inthe lower left corner of the screen.

6. Vibration units: The currentvibration units and units type aredisplayed just below the vibrationamplitude readout.

7. Alarm Indicator: If the currentvibration level is higher that the userset alarm level. A reverse video**ALARM** will appear just belowthe vibration readout in the lowerleft corner. (See balance options2.2.1 to set the alarm)

8. Free Run/Averaging Indicator:This indicator will read FREE RUNuntil you press the AVG DATA key.Then it will start indicating the totalnumber of samples in the currentaveraged display values. This willcontinue until the Save Run or Clr

Scrn keys are pressed.

9. RPM Indicator: A digital readout of the tachRPM is provided. This can be in RPM or Hzas selected in the control panel. (Sect 1.10.9)

10. Phase Readout: A digital readout of the phaseangle of the vibration signal relative to thetach signal is provided. Units are alsodisplayed.

11. Bandwidth: The current filter bandwidth isdisplayed. This is user selectable in thebalance options menu.

12. Full Scale Range: The full scale level of thepolar plot is displayed here. Note that thislevel is independent of the current full scalerange selected by the auto range function.

Chapter 2 Balance Mode

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This value can be changed at any time usingthe up and down arrow keys.

13. Update/Freeze Indicator: This is a smallflashing indicator that blinks “update” forevery data sample that is collected anddisplayed. It changes to “Freeze” when theStart/Stop key is pressed. It shows “SAVED”when the screen is a recalled file.

14. Time and Date - Optionally as selected inControl Panel. (Sec 1.10.4)

15. Battery Status Indicator - Voltage andanalog bargraph of battery energy remainingalong with “Charging” status.

16. Status Indicator Area - This part of thescreen will indicate “Auto Ranging InProgress” or “Initializing Fixed Gain” duringthe autorange period. It will indicate “NoTach” if tach signal is not present. It willindicate “Changing Tach” if tach rate ischanging too rapidly to display. It will indicate“Lost Tach” if the tach signal is lost.

17. Template name. This is the name of thetemplate or group file used when this historyfile was created.

18. File Name - Currently open history file name.

19. Screen Title - The balance run number willincrement for each new balance data point.

20. Current plotted data point - This is the plotpoint, IPS and Phase plotted in real time. Therun number will appear in the circle.

21. Low Input and Overload Indicator - Thisflag will occur during normal operation if theunit is set for automatic gain ranging (thedefault setting). The autoranging functionraises and lowers the gain as the input changesamplitude in order to obtain the best signal tonoise ratio. This flag is just an advisory anddoes not mean anything is wrong.

2.2 Balance Function KeysThe Prop/Rotor Balance Mode provides thefollowing function keys:

Mode - This key allows you to change modes

File - This key provides access to the File DirectoryScreen.

Task - This key allows you to select the task orsetup the tasks as explained in section 2.9.

Help - This key provides information about thecurrent function.

Bal Opts - Balance Options: This key is describedin the next section

Save Plot - This key will save the current screen. Itwill prompt you to enter a name for the plot file, oryou can simply accept the auto-assigned name.

Avg Data - This key will engage averaging of thevibration data. The kind of averaging used is userselectable in the balance options menu.

Clear Screen - This key clears the data buffer andstarts the measurement over. It also clears anyaveraged data and starts averaging over.

Start Stop - This key freezes and unfreezes thescreen. Useful for saving a screen plot.

2.2.1 Balance Options

This key leads to a screen where you can controlhow the Prop/Rotor Balance Mode operates.

Set Sens Factor - This function allows you to enteran adjustment sensitivity. This is normally usedwhen you have balanced this type of rotor beforeand you know the adjustment sensitivity. This willavoid the first “Learning Run” and possibly save arun

Sens Factor is the factor used by the MicroVib II tocalculate the amount of adjustment (weight, pitchlink, tab sweep etc.) to be applied to the subject inorder to balance it. If this key is pressed, you willbe prompted to enter a new value (Limits .1 to9999) or press enter to leave the value alone. Thisnumber is a ratio and therefore unitless. You canthink of it as the number of grams per IPS or flatsper IPS if these are the units you want to work in. Ifyour preference is the number of pounds per g ordegrees per IPS, this will work equally well. If youhave balanced the subject aircraft before and youremember the Sens factor determined before (this


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value is printed on the history report), this numbershould be keyed in to save time and engine starts.

Set Tach Offset - From here you can enter a tachoffset. This is normally used when you havebalanced this type of rotor before and you know thetach offset. This will avoid the first “Learning Run”and possibly save a run.

Tach Offset is the phase angle offset the MicrovibII uses to determine where to add the correctionweight after the phase measurement is made. If thiskey is pressed, you will be prompted to enter a newvalue (Limit 1 to 360) or press enter to leave thevalue alone. For most propeller systems with thevibration sensor mounted vertically at the propellerend of the engine and the photo tach at 3:00(viewed from the front) this angle will be 90degrees. If you have balanced the subject aircraftbefore and you remember the Tach Offsetdetermined before (this value is printed on thehistory report), this number should be keyed in tosave time.

As a general rule, you can estimate the tach offsetby considering the photobeam intercept location tobe zero and determining how many degrees thetarget blade must go through before it aligns withthe vibe sensor sensitive axis.

Set Display Units - This leads to a menu thatallows you to select display units (Sensor,Acceleration, Velocity, Displacement) or selectMetric Units, or select units type (RMS, Peak, Peakto Peak, Average). The currently selected units areshow as black (reverse-video) keys.

Overlay Balance History - This option will plotall data points on the screen and connect the pointswith lines as you perform the balance. Turning thisoption off will only plot the current reading for acleaner looking display. (Default is on)

Linear (Block) Averaging - This type ofaveraging treats every data point equally usuallyleading to a very stable reading after manyaverages. (Default)

EXP (Smooth) Averaging - This type of averagingweights the most recent data points heavier thanolder data points. If the data is unsteady, this type

of averaging will continue to vary even with manyaverages.

Start Analysis - This simply exits this menu backto the Balance Screen.

Advanced Options - Leads to the followingadditional balance options.

Set Alarm Level - This function lets you set thealarm level to any desired value. Setting the levelto 0.0 disables the alarm function. Default = 1.2

Set Target Level - You can enter any value here touse as a target level you want to achieve whenbalancing. A solid line will be displayed on thepolar plot at the target level. Setting the target levelto 0.0 disables this function. Default = 0.2

Hann Window - This key disables the Hannwindow function in the balance filter. Turning offthe Hann window enables a rectangular windowfunction. Default window is Hann.

Computer- This function is a specialty calculatorthat makes adding and subtracting weights(vectors) very easy. (See Section 2.4)

Set Min (Learn) Moveline. This function allowsthe user to specify the minimum moveline requiredbefore the unit will learn. The default setting is .1.Do not change this unless you understand theeffects.

Set Order - This function allows the unit to take abalance type vibration reading of an object that isturning at a different speed but locked to the rotorthe tach is sensing. Example: If the tach isdetecting the 1 per rev of the rotor on a two bladehelicopter, by setting the order to 2, you can take abalance reading of the blade rate vibration. Thisfunction is limited to integer multiples of the tachrate. Default = 1

Set Filter Bandwidth: This function allows you toset the filter bandwidth used in balancing. Anarrow filter takes more time for each sample.Bandwidths of 20%, 10%, 5%, 2% are available.10% bandwidth works fine in almost every case. .


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2.3 The Balance Solution ScreenThe solution screen displays a suggested balancesolution. This solution consists of the amount ofadjustment to be made and the location for it.

2.3.1 Solution Screen Data

1. Run number.

2. Vibration Level stored for this run.

3. Phase angle stored for this run.

4. Task Name (User definable in task setup).

5. Location (angle) where adjustment is to bemade.

6. Amount of adjustment.

7. Sensors currently active.

8. Battery Status.

9. Template or Group File name.

10. History File Name.

2.3.2 Solution Function Keys

The Solution Screen also has a menu of selectionsto manipulate the solution for ease ofimplementation. In Standard Rotor mode thesolution screen initially shows a single adjustmentat a single angle location. For the first run makingexactly this adjustment at exactly this location is

NOT important. What is VERY important is thatwhatever adjustment and location you use, be sureto enter that data accurately.

Split Weight

In Standard Rotor mode, when a solution ispresented initially it will always be a singleadjustment at a single location. The SPLIT WTkey allows you to split that adjustment into twonearby locations that you find practical on thesubject. This can eliminate the need for drillingnew holes if nearby locations are alreadyavailable. The screen shown here is after thesplit weight key has been pressed.

In Program Rotor mode, the available weight ormove locations are pre-programmed in the tasksetup, so all solutions are presented alreadysplit. Pressing the SPLT WT key (or the UP andDOWN arrows) will scroll thru all the availablecombination that will work.

Learn Mode

This key turns learn mode on and off. With learnmode on, the MicroVib II will learn from theadjustments and measurements to automaticallycorrect the aircraft factors on each run. If the vectorlength of the move line from one run to the next isless than .1 vibration units the learning mode isdisabled. This minimum move line is adjustable inBalance Options, Advanced Options. With learnmode off, the unit will never change the aircraftfactors.

The VIEW HIST key is used to display the historyscreen for the current task. While balancing thesubject, the Microvib II is automatically making acomplete documented record of all the levelsmeasured and adjustments made on the aircraft.This display shows the Run number, MeasurementRPM, Vibration level with units of measure, Phase,Sensitivity Factor, and Tach Offset. The detailwindow at the bottom of the screen also shows theamount of adjustment made and its location as wellas the time the adjustment data was entered.


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The BACK TO PREV key acts like an undo key.It takes you back to the previous step in the balanceprocess and lets you do that step over.

The ENTER CHGS key is like an enter key. Itmeans you are ready to go to the next step, which isto actually enter the amount and location of theadjustment you have made to the rotor.

Remove Previous Changes Key

After the first run, the solution screen will haveanother key available, the RMOVE PREVCHNGS key

Pressing the RMOVE PREV CHNGS key tellsthe MicroVib II that you are removing the trialmove done after the first run. The solutiondisplayed after you press this key will be a solutionto the original vibration reading of run 1 correctedfor “learned” aircraft factors. If you don’t press theRMOVE PREV CHNGS key, you must leave thetrial move alone and carry out the new solutiondisplayed.

In this way the RMOVE PREV CHNGS keyallows the user to choose the vibration for which asolution will be computed. The first solution isusually based on "average" aircraft factors mostcommonly found in the field (Factory defaults).This solution is a "trial" move to accuratelymeasure the true aircraft factors for this subject.Often this trial move is not at a good location, sothe RMOVE PREV CHNGS key allows you totell the Microvib II to compute the solution for theoriginal reading using the just learned factors.

It is strongly recommended that the RMOVEPREV CHNGS key be only used once, immediately after the Analyzer has characterizedthe rotor being balanced (Normally after Run 2).After this, use of the RMOVE PREV CHNGS keyshould be avoided. (If this key is used after Run 2,the weight computer is locked out.)

Weight Computer

Pressing the COMPUTER key in the solutionscreen transfers the currently displayed solutioninto the Weight Computer. See next section for anexplanation of the Weight Computer.

The remaining function keys work just as explainedin section 2.2.

Enter Changes Screen

From the Solution Screen, pressing the ENTERCHGS key advances the MicroVib II into the EnterWeight screen (if Learn Mode is on) and then intothe Enter Location screen. After entering theweight and location, pressing the OK key leads tothe Verify Screen.

Verify Screen

The Verify Screen will display all weight changesthat have been entered. These values should bechecked very carefully before proceeding to thenext measurement. This is extremely important forthe MicroVib II to be able to learn.

The Verify Screen also displays a predictedvibration at the bottom of the screen. Thisprediction is based on the assumption that the Sensand Tach values are correct for this rotor,everything up to this point has been done correctlyand the rotor has a linear response.

If Learn Mode is off, the weight changes are notentered and therefore the Verification screen willdisplay “Previous Changes Were Retained andTrim Weight Added”.

Back to Previous

Pressing the BACK TO PREV key in the VerifyScreen will cause the Microvib II Analyzer toreturn to the Balance Solution screen seenpreviously. This key should be pressed if incorrectweight and/or location information has beenentered.

Start Analysis

Pressing the START ANLS key will store allparticulars of the current solution to the Historyand begin a Balance Measurement for the next run.


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2.4 Weight ComputerThe Weight Computer functions can be used in avariety of ways to calculate balance solutions.

2.4.1 Enter Weight

The ENTER WT allows the user to clear the currentdisplay and enter an amount of weight to bemanipulated. The weight to be entered may be asingle or a split weight. If the Weight Computer isin single weight mode, the user will be prompted toenter the amount of the weight and the anglelocation. If the Weight Computer is in split weightmode the new weight will be automatically split tothe two angles currently in memory.

2.4.2 Split Weight

The SPLIT WT key allows the user to manipulatea single weight and angle solution and convert itinto a split solution, calculating the equivalentamount of weight to be added to two real availablelocations on the rotor.

After a single weight and location have beenentered, the computer can calculate the amount ofweight to be added to two nearby angle locations oneither side of the current angle to produce the samebalance solution. This is done by pressing the splitkey and entering the two desired angle locations.The split key will appear in reverse video whenevertwo locations are displayed

Un-splitting Weights

If two weights and locations are displayed, theweights can be combined back into a single weightand location by pushing the SPLIT WT key again.The SPLIT WT symbol will return to normalvideo. The weights can be quickly split by pushingSPLIT WT, OK, and OK again. This will re-enterthe two weight locations stored in memory from theprevious screen.

The SPLIT WT key is a toggle. Feel free to usethis function to experiment with split and unsplitsolutions which utilize different split weightlocations until the most easily realized finalsolution is determined.

2.4.3 New Radius

The NEW RAD key allows the user to transfer theamount of weight at one radius to a new radius.This is often useful when moving weights fromtemporary locations to final flight worthy locations.By pressing the new radius key you will beprompted to enter the old (temporary) radius andthe new (final) radius (limits .1 to 9999). Thisfunction is a ratio, so the unit of length used isunimportant, so long as the same unit is used forboth the new and old radius. The new radiusfunction will work for both split and singlesolutions.

2.4.4 Add Weight

The ADD WT key allows the user to add weightvectors to the currently displayed values. In doingso, the currently displayed weights will becombined with the weight to be added. This isparticularly useful when entering weights whichhave been accumulated at temporary locations andit is desired to transfer the temporary weights andthe "residual" solution generated on the last run to anew, permanent location.

2.5 Weight Computer ProceduresThe most common uses of the weight computer aredescribed here. You may find other uses not listed.

Moving from Temporary locations to permanentlocations.

After good balance has been achieved usingtemporary weight locations. The Weight Computeris used to transfer the weights added to balance arotor from temporary (easy access) locations tofinal (flight worthy) locations.

For example, a balance is performed on a smallfixed wing prop by adding washers under the headsof two spinner attachment screws. When thebalance is complete, the Weight Computer can beused to combine the weights into a single imaginarylocation, then change the radius to the final locationradius and then split the weights onto two "real"locations available for flight worthy weights.


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Smallest Weights Too Big

In some cases, the smallest weight that can beattached is a short bolt and nut. But a bolt and nutare more weight than you need at each of the twosplit weight locations. By unsplitting the solutionand then re-splitting it to a wider angle, the solutionwill call for more weight at each location, solvingthe problem.

Removing more Weight than is there.

Problem: The solution is telling me to remove moreweight than is there. What do I do?

This problem can occur if you pick split locationsthat are too close to the ideal single weightlocation. Example: The ideal single weight is 29.44grams at 244.9 degrees. You pick split locations of240 and 270 degrees. The unit will tell you to put25 grams at 240 degrees and 5 grams at 270degrees. If the rotor is slightly nonlinear, the nextsolution could be +8 grams at 240 and -8 grams at270 degrees. An impossible solution. Go to theweight computer and:

1. Press ENTER WT and enter the weightcurrently at 240 degrees. Enter 25 at 240degrees.

2. Press ADD WT and add the weight at 270degrees. Enter 5 at 270 degrees.

3. Press ADD WT and add the new solution at240 degrees. Enter 8 at 240 degrees.

4. Press ADD WT and add the new solution at270 degrees. Enter -8 at 270 degrees.

5. Display should show 33 at 240 and -3 at 270.Press SPLIT WT key and the single weightsolution will be displayed 30.44 at 237.2.

6. Press SPLIT WT again and key in better splitlocations 210 and 270.

7. Now solution is 19.05 at 210 and 16.05 at 270degrees. Remove the weights that are on therotor and implement this new solution.

If you want the Microvib II to learn from thissolution, you have to enter the originalsolution you were trying to implement. In thisexample that was +8 at 240 degrees and -8 at270 degrees. Otherwise, just turn the learningmode off.

Spreading Weights over Many Locations

A problem occurs when you have a large numberof weight locations, but each one is limited to avery small amount of weight. A simple twolocation split will not allow you to add enoughweight. Example; Your rotor has 36 weightlocations (every 10 degrees) but the max weight ateach location is 20 grams. The solution calls for 50grams at 90 degrees, which is more than you canplace at two locations. Use the Weight computer asfollows:

1. Press ENTER WT and enter the solution.Enter 50 grams at 90 degrees.

2. Press ADD WT and enter the max weight atthe location closest to ideal. In this case enter-20 at 90. Entering the weight as a negativevalue is the same as subtracting this weightfrom the solution. Now the screen shows theremaining weight to be added, 30 grams at 90degrees.

3. Press SPLIT WT and enter two split angleson either side of the ideal. In this case wechoose 80 and 100 degrees.

4. The solution now presented is 15.23 at 80 and15.23 at 100 degrees. This is a realisticsolution. You can use this method to spreadthe solution over as many locations as needed.You just have to remember that as you addweight to the rotor, you have to subtract eachweight from the solution until you have aweight that can be split across two locations.

If you want the Microvib II to learn from a solutionspread over many locations, use the WeightComputer function ENTER WT to enter one of theweights and angles, and then use the ADD WTfunction to add the additional weights in until youhave the sum of all the weights. This sum shouldmatch closely with the original solution you were


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trying to implement. Enter this sum of weights intothe unit in ENTER CHGS at the solution screen.Otherwise, just turn learning mode off.

2.6 Balancing ProcedureThe MicroVib II can be used to balance just aboutany form of prop or rotor system.

2.6.1 Generic Balance Procedure

Following is the simplest form of balanceprocedure. This procedure can be used to balanceany constant speed spinning mass in one plane.This procedure assumes:

1. You have or can make weight attachmentlocations on the machine as required.

2. The accelerometer and photocell are mountedproperly and connected to the unit as required.

3. You will use the Prop/Rotor Protractor.

4. The weight or adjustment locations are all atthe same radius.

Setup

First you must create a new balance history. PressON OFF key, MODE, CONTROL PANEL, NEWHISTORY FILE, select a template or group filethat is apropriate. See section 2.10.

Procedure

1. Start machine to be balanced. Allow system tothermally stabilize and operate at RPMcommonly used to perform balance.

2. Press ON OFF key. Wait for RPM reading tostabilize.

3. Press AVG DATA key. Wait for at least 8averages. More if unstable conditions.

4. Press SAVE RUN key. Solution on screen ISNOT a correct solution.

5. Select a reasonable trial weight and add it tothe machine. Note angle location.

6. Press ENTER CHNGS key and enter exactweight amount and location. Press OK.

7. Start machine and press START ANLS key.Wait for RPM to stabilize.

8. Vibration level may be higher or lower thanbefore. This is irrelevant.

9. Press AVG DATA key, wait for at least 8averages.

10. Press SAVE RUN key. Verify Microvib IIlearned by pressing VIEW HIST, VIEWLIST, see that Sens and Tach values havechanged. If they have press DONE andcontinue on to step 11. If not press RMOVEPREV CHNGS key and increase the amountof weight added to the same location to be surethe vibration level changes more than .1. PressENTER CHGS and enter this weight andlocation. Press OK. Return to step 7.

11. Press REMOVE PREV CHNGS key. Noteideal single weight location angle. Inspectrotor and find two real locations on either sideof ideal. Use Prop Protractor to measure anglesaccurately.

12. Press SPLIT WT Key. Enter two weightlocations that are available on either side ofideal location just noted.

13. Screen will show solution. Write downsolution. Remove the trial weight you placedon rotor in step 5 above. Implement newsolution as accurately as you can on rotor.

14. Write down the actual weights and locationsused.

15. Press ENTER CHGS key. Enter actualweights used at each location.

16. Verify Screen. Double check that screenagrees exactly with what you did. Note thatpredicted vibration should be very low.

17. Start machine and Press START ANLS key.Wait for RPM to stabilize.

18. Press AVG DATA key, wait for at least 8averages.

19. Press SAVE RUN key. Solution will bedisplayed.


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20. If IPS level is acceptable, you are done. PressVIEW HIST and VIEW PLOT to see agraphic plot of the action.

21. If IPS came down substantially and you wantto lower it more, implement the solutionshown by adding to or subtracting from theweights previously applied. Example: If youpreviously placed 23 grams at 60 degrees andnow the solution says +1.2 grams at 60degrees. This means you add 1.2 grams to the23 grams already there. If the solution istelling you to remove more weight than isthere, or is telling you to add more weight thanis allowed at the location, you can use theweight computer to finish the job (Sect 2.5)

22. If the IPS level did not come downsubstantially or got worse, either a mistakewas made in the procedure, or the machine ismechanically damaged and will not balance.Inspect the View Hist screen to see if the Sensand Tach Offset columns make sense* andcheck the View Plot screen to see if the movelines went in the expected direction andlength. Evaluating these two screens willusually lead to what may have gone wrong.Start over and repeat the procedure. Ifrepetition does not work, ask for help orcarefully inspect machine for damage.

* On first line, sens and tach should be the defaultor initial values. They should change from line 1 toline 2 as the Microvib II has learned. From line 2 to3 and forward, the sens and tach values wouldideally remain constant, but you should expectthem to vary slightly. Sens usually will vary +/-25% and Tach will usually vary as much as +/- 25degrees.

2.7 Weighing ProceduresReducing the Effect of Wind

When weighing out balance weights using the gramscale, shelter the scale from any wind as readingswill be much more stable.

Changing bolt length using Tare.

You will often be faced with using a longer bolt tohold new balance weights. You can weigh the oldbolt, weigh the new bolt and then subtract thedifference, but there is a simpler method.

Place the old bolt on the scale and press the TAREkey on the scale. Wait for the scale to read 0 andthen remove the old bolt and add the new bolt andnew weights. The scale will read the net weightadded to the location.

Weighing Very Light Weights

To weigh very small weights accurately, weigh 10of the weights and divide the reading by 10.

2.8 History FileThe MicroVib II stores the complete history of thebalancing operation including task, measurementRPM, vibration level, phase angle, adjustmentsmade, time, date and the aircraft factors (SensitivityFactor and Tach Offset) for each balance run. EachHistory file can have up to 10 tasks. Each task canhave a unique name, can use different sensors, canhave names for adjustment locations (Red Blade,Target Blade, Chord Arm etc.) and names for thetype of move (flats, degrees, placquettes etc) andcan have different initial aircraft factors. The unitcan store a large number of history filesindefinitely.

2.8.1 View History

To view the current task history from the BalanceRun, Solution or Verify screen, press the VIEWHIST Key. To view the history for another task,you must change tasks by pressing the TASK key.

2.8.2 Default History Files

When the unit is first received it always starts outwith an initial history file called DEFAULT.HST.New balance data will be stored in this defaulthistory until a new history file is created. When theDisk is formatted (erased) the default history file isDEFAULT.HST. The current history file is notwritten to disk until you create a new history file orturn the unit off.

2.8.3 Printing History (See Section 1.14)


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2.8.4 Clear History

History files will be retained indefinitely, but if youwant to erase a history, there are three ways.

1. If you want to clear only the history for thecurrent task, view the history, press theCLEAR HIST key and then the DOWNARROW key as prompted.

2. If you want to clear the history for all tasks inthis history file, you can erase the file. Seesection 1.13.3.

3. If you want to clear (erase) all balancehistories and all other files as well, you canformat the disk. See Section 1.10.17.

2.8.5 New History File

If you want to close the current history file and startfresh with a new one, press the MODE key in anyscreen, then press the CONTROL PANEL key andthen NEW HISTORY FILE key. This will savethe current history file to disk and the Select Groupscreen will prompt you to choose a group file or atemplate for a group file. If the aircraft you areworking fits any of the templates or group fileslisted, choose that template or file. If the aircraftdoes not match any of the templates or group filesshown, try to pick the template of the type ofaircraft that is most similar to the one you areworking. You can modify the task settings in thegroup file after you have chosen it. Once you getthe task settings the way you want them, you cansave the settings by the SAVE(EXPORT) GROUPfunction.

2.8.6 Evaluating History Data

The view history screen data can provide veryuseful insight when balancing problems arise. Thecolumns labeled Sens and Tach are the ones towatch. The Sense and Tach of the first line shouldbe the default values from the group or template fileused or they may be the values keyed in or thestarting values from the App note. The valuesshould change from the first line to the second line.This means the MicroVib II “learned” the responseof the rotor. If the values did not change, an errorwas made. Either learning mode was turned off, orthe first trial adjustment was too small. If the move

line from vibration point 1 to point 2 is less than .1IPS, the unit will not learn. This minimummoveline can be adjusted in Balance Options,Advanced Options.

If learning mode was kept on during the rest of thebalancing process the Sens and Tach value shouldhave stayed pretty much the same. It is normal forthe Sense value to vary up to about 25% and theTach value to vary up to about 30 degrees, but ifthey vary much more than these “fuzzy” values,either a mistake was made or the rotor ismechanically unsound or “nonlinear”. Experiencewill lead you to find what kind of wear or damagecauses what kind of balancing problems. Nonlinearrotors are generally well known among mechanicswith balancing experience on that rotor or shaft.

2.9 Task FunctionsEach History can have up to 10 tasks. Tasks areused on multi-engine prop aircraft to keep all the data on that aircraft in one history. This function isalso used to keep all the tasks involved in workinga helicopter in one history. A typical helicopterhistory might include five tasks: Ground Track,Tail Rotor Balance(T/R), Main Rotor Hover LateralTrack & Balance(HoverLat). Main Rotor MidSpeed Vertical Track & Balance (MidSpeed), MainRotor High Speed Vertical Track & Balance(HiSpeed). The TASK key leads to the Select Taskscreen where you can select tasks or setup tasks.The balance task names are defined by the groupfile selected when the history file is first created.The task names and details can be changed in TaskSetup (see below).

The Task function also helps keep data organized.Every time a waveform, spectrum or track plot issaved using the SAVE PLOT function, the currenthistory name and task name is recorded anddisplayed when that plot is recalled.


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2.9.1 Task Setup

In the Select Task screen, the currently selectedtask is darkened. If you press the TASK SETUPkey, it will lead to the Task Setup screen. Thisscreen has five function keys as follows:

Set Task Name - This key leads to analphanumeric data entry screen where you canenter the name you want for the current task.

Set Input Channels - You can select whichaccelerometer and tach sensor is to be used for thistask.

Set Initial Sensitivity Factor- This data is usuallyprinted in the app note for the target aircraft rotor.Or you may have balanced a rotor of this same typebefore and this value is in your records.

Set Initial Tach Offset - Same as above.

Restore Task Defaults - If you want to return thetask setup values to their factory default values,press this key.

2.10 Group FilesGroup files are a way of setting up the MicroVib IIto perform a set of track & balance tasks with tasknames, adjustment location names, adjustment unitnames, location angles and radii. These setups helpthe user understand the solutions provided bypresenting them in a clear fashion. These files cancontain up to 10 predefined tasks. Each task can beeither a standard rotor or a program rotor.

A standard rotor is one where all adjustmentlocations have the same radius. Solutions will bepresented as a single adjustment at a single locationand you can then split that solution to any twoangles. Two examples of standard rotors are mostpropellers and Bell 206 tail rotors with balancewheel.

A program rotor is one with 3-8 locations on therotor where adjustments can be made. Programrotors can have adjustment locations at multipleradii. Solutions will be presented already splitbetween the available locations and you can scrollthru the various possible solutions without everkeying in any split angles.

Every history file has a group file contained withinit. The group file can be thought of as the structurefor the history file. When you create a new historyfile, you will have to specify a group file ortemplate to be used. Once this is done, you canmodify the current group file by selecting theTASK key available in any balance screen.

2.10.1 Creating a Group File

Although you can create a group file by itself, it iseasier to create a new history file and then changethe task definitions in that history file. When youare happy with the task definitions, you can thenuse the SAVE (EXPORT) GROUP function in theAdvanced Controls section of the control panel tosave the group file to disk by itself.

Procedure:

1. Press MODE, CONTROL PANEL, NEWHISTORY FILE.

2. Select Group screen is displayed. Choose atemplate or group file that is most like theaircraft you are working.

3. Enter History Name screen is displayed. PressOK to use the name automatically created orenter a name of your choice.

4. Select Operating Mode screen is shown. SelectProp/Rotor Balance and press START ANALYSIS key.

5. Balance Run screen is shown. Press TASKkey.

6. Select Task screen is shown. Select the taskyou want to set up first and press the TASKSETUP key.

7. Task Settings are shown. At this point you canselect STANDARD ROTOR or PROGRAMROTOR, you can SET TASK NAME tochange the task name. You can SET INPUTCHANNELS, to select the acc and tachchannels to be used. You can SET INITIALSENS FACTOR or SET INITIAL TACHFACTOR if you know the correct values.


2-11

8. If you have chosen PROGRAM ROTOR instep 7, you can change the program values bypressing the SET ROTOR PROGRAM key.

9. Rotor Setup Screen is shown. You can changethe number of locations by pressing the SETNUMBER OF LOCATIONS key andentering 3-8. You can select a particularlocation to modify using the UP and DOWNarrow keys. An arrowhead on the screen willindicate which location you are currentlymodifying. You can change the adjustmentunits, location name, location angle or radiusvalue by pressing the appropriate key shownand entering the new value or name.

10. At this point you can also use the COPYLOCATION function key to copy theinformation from one location over to anotherlocation. You do this by positioning the arrowon the location you want to change andpressing COPY LOCATION, you will beprompted to enter the location of the source ofthe data to be copied

11. At this point you can use the RESETLOCATION key if you want to reset thecurrent location to default values. Defaultvalues for adjustment units are Grams, foradjustment location is LOC(X) where (X) isthe location number. For radius, the defaultvalue is 1.

12. At this point you can set the Skip Factor* Ifthe number of locations is 5 or 6, you can setthe Skip Factor to 1 by pressing the RIGHTarrow key. If the number of locations is 7 or 8,you can set the skip factor to 1 or 2 by pressingthe RIGHT arrow key.

13. When the task setup is finished, press theDONE key to exit back to the Select Taskscreen. Repeat steps 5-12 for the rest of thetasks.

*The Skip Factor is a device used (in programrotor) to tell the Microvib II to present all solutionssplit wider than just two adjacent locations. A skipfactor of one will force all solutions to skip overone blade and split the solution between blades 1

and 3 for example instead of 1-2 or 2-3 on a 5 blade rotor.

2.10.2 Templates

Templates are group files that are included in thefirmware for the unit. They cannot be modified orerased. They can be thought of as basic startingpoints to make group files for the most commonkinds of helicopters. The MicroVib II includestemplates for the Eurocopter AS350, Bell206/206L, Bell 205/Huey, Bel 222, Hughes 500C,McDonnel/Douglas MD500D/E, Robinson R22,Schweizer S300C, Augusta A109, Sikorsky S-76,and any fixed wing prop aircraft. Virtually anyaircraft can be accommodated by starting with oneof these templates and then modifying the tasksettings to match the target aircraft. When the tasksare correct, you can save the group file as follows:

2.10.3 Saving A Group File

After you have made changes to the group file inthe current history file, you can save this group fileas a separate item on the disk.

1. Press MODE, CONTROL PANEL,ADVANCED CONTROLS, SAVE(EXPORT) GROUP.

2. Enter Group Name screen is displayed. Youcan accept the name automatically assigned orenter any name you like. Press OK, DONEand DONE to get back to the Select OperatingMode Screen.

2.10.4 Printing Out the Group File

Group files can get pretty involved, so it is helpfulto be able to print out the group file on single sheetof paper. This makes it easier to check to be sure allthe details of the group file are correct.

You can print out a group file by downloading thegroup file to MicroBase and print from there toyour PC printer.


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2.10.5 Editing Group Files

It is easier to edit group files on your PC usingMicroBase. You can also share group files withother users via email with MicroBase. See the helpfile in MicroBase.

2.11 Reference Information2.11.1 Propeller-Rotor Protractor

Adjustment location angles must be determinedaccurately in order for the MicroVib II to learnaccurately. This task can be confusing as thedirection of rotation is a critical factor. ThePropeller/Rotor Protractor is designed to make thistask very straightforward.

Following is a procedure for determining the anglelocation of a weight attachment point.

1. Check the rotor's direction of rotation. Forrotors which turn CCW, the BLUE side of theProtractor must be used. For rotors which turnCW, the RED side must be used.

2. Next rotate the Protractor until the 360 degree"pointer" is aligned with the phase reference(this will usually be the reflective tape).

3. Center the protractor on the spinner or rotordisk.

4. Now sight along the protractor's edge toidentify the proper angular location of theweight addition points. Alternately, visualizean imaginary line from the attachment point tothe center of rotation. Note where this lineintersects the protractor.

Alternate Method for Measuring Angles.

Another method for measuring angles on fixedwing props is to use the Prop-Protractor to get arough idea where the angles are, but to use anarrow blade tape measure to more accuratelymeasure location angles.

1. Use the protractor to mark one location on theperimeter of the spinner, typically one screwlocation. This is the reference location.

2. Measure the distance from one blade to thenext and divide the angle between blades by

this distance. The resulting value is thenumber of degrees per inch. Example: A 14.3inch diameter 3 blade spinner has acircumference of 45 inches. Blade to bladedistance is 15 inches. 120 degrees divided by15 inches equals 8 degrees per inch.

3. To measure any other location on the spinner,measure the distance from the referencelocation to the new location and multiply thisdistance by the degrees per inch determined instep 2.

4. Double check the new location angle byverifying that the prop-protractor is inapproximate agreement with your tapemeasured angle. Be sure to pay attention to therotation direction. The locations determinedby tape measure will be more accurate thanmeasurements made by sighting using theprop-protractor.


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2.11.2 Estimating Tach Offset (Props)

The tach offset is used by the MicroVib II whencalculating the angle where the weight or move isto be applied to the rotor. Unless you enter a tachoffset when you start a balance job, the first weightlocation will be based on the default tach offset,which is usually not correct. The MicroVib II willautomatically learn the tach offset after the firstbalance move, but you can save time by estimatingthe tach offset from the geometry of the installation.

Procedure :

1. Using the prop protractor (while facing thepropeller from in front of the aircraft), alignthe zero degree mark with the sensitive axis ofthe mounted accelerometer.

2. Note the angle of the mounted photocell. Thisangle is a good estimate of the tach offset.

It is important to use the side of the protractor thatmatches the direction of prop rotation.

2.11.3 Estimating Sensitivity Factor

The sensitivity factor is used by the MicroVib IIwhen calculating the amount of weight oradjustment that is to be applied to the rotor. Unlessyou enter a sensitivity factor when you start abalance job, the first weight amount will be basedon the default factor (80), which is usually notcorrect. The MicroVib II will automatically learnthe sense factor after the first balance move, butyou can save time by estimating it using thefollowing guidelines.

The sensitivity factor is a function of the mass ofthe engine-prop combination, the radius of theweight attachment point and stiffness of the engine mounts. This information is not usually available tothe user, so we offer here a set of guidelines.

1. Most common piston prop single and twinengine aircraft adding weight to spinnerscrews or spinner backing plate. Sens Factor =50-80, (80 is the default).

2. Medium sized aircraft with turboprop powerplant. Sens factor 100-120.

3. Large turboprop aircraft, like C-130, E2-C2,P3 etc. Sens factor 250-300.

4. Tail Rotors, Drive shafts, Helicopter MainRotors etc. Sens factors vary widely, see appnote or ask experienced users.

WARNING: It can be dangerous to addtoo much weight to a rotor, so unless youhave experience, start with a smallamount of weight and let the MicroVib IIlearn the response. Keep in mind that themove line must be greater than 0.1 IPSfor the unit to learn. This mimimummoveline value can be adjusted in BalOpts, Advanced Options.


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Accelerometer Sensitive Axis

PN 1014 & 1880 PN 1460

2.12 Helicopter Track & BalanceHelicopter Main Rotor Track and Balance canseem complicated at times, but if you break it downinto a series of small steps, each step is simple andunderstandable. We have produced a flow chartthat depicts all the steps in the process. If you willread this text over, and go over the flow chart a fewtimes, all the pieces will fit together in a logicalmanner.

Basics.

This flow chart uses short phrases like "SelectMidspeed Task" or "Measure Vibration", or"Measure Track". We assume you know how tooperate the MicroVib II to do each of these things.If you are not familiar enough to do these things onthe unit without getting stuck, it is best to go to theend of this section and familiarize yourself witheach of these procedures.

The key points in the flow chart are the decisionpoints. These are labeled with numbers that we willrefer to here in the text. Following is a discussionof each of these decisions to be made during thebalancing process.

Safety Statement (1)

If an aircraft is shaking badly on the ground, it isbest to get the ground track and ground lateralvibration down to a reasonable level beforeproceeding. Performing a ground lateral balance isvery simple, just like balancing a propeller. Onceyou go to a hover, if the hover lateral is severe, youshould probably balance out the hover lateral to areasonable level before proceeding to forwardflight. If the hover track is really bad, you shouldadjust pitch links to get it within reason beforegoing to forward flight. In forward flight, if themidspeed track or vibration is severe, it is wise tomake a pitch link move to get the midspeed trackand vibration within reason before going to highspeed.

Decision 2

You need to start with good ground track, so thisstep is necessary. If you are doing the tail rotorbalance, you can gather ground track readings andmake adjustments at the same time as doing the tail

rotor balance. Do not try to get ground track"perfect", as it will be changed somewhat duringthe rest of the process. A track reading of 1/2 inchor less is fine.

Decision 3

This is the point you decide whether to stop makingpitch link or tab adjustments or continue to makethem. Remember, the track may not be perfect, butif the midspeed and high speed vertical vibrationlevels are below target levels, we recommend yousay yes at this point and go on to finish up by doingthe hover lateral balance. Never work the hoverlateral first, it is a waste of time.

Decision 4

This is the heart of the process. You must look atboth the track data and the vibration data to makethis decision. Viewing the track data, if a blade isslightly out of track at hover, and gradually moreout of track at mid speed and high speed, it is bestto make a pitch link change. If a blade is fine inhover and midspeed, but sharply climbing or divingat high speed only, a tab move is best. After thefirst flight, use only the track data to decide whichblade to tab or P/L. Make only a single move, andenter that move into both midspeed and highspeedtask. Each blade has a location name and an anglein degrees.

After the second flight, the Microvib II will havelearned based on the move entered and it willprovide a solution for the next flight. The solutionwill be in the same form as the move entered beforethe flight (e.g. tab = tab, p/l = p/l). If the task issetup as a program rotor, the solution will normallybe split between two adjacent blades (Read aboutskip factor in Section 2.10.1). You can scroll thruall possible solutions by pressing the SPLIT key.Look at the solution and the track data to see if thesolution will make the track better or worse. If thesolution is going to make the track worse, press theSPLIT key until you find a solution that will makethe track better.


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2-16

Fly Aircraft at High Speed

Select High Speed Task & MeasureVertical Vibration

Measure Track

Runup Aircrafton the ground.

Hover Aircraft

Install Equipment onAircraft per App Note

Select Hover Lat task &measure Vibration

Fly Aircraft at Mid Speed

Measure Hover Track

Adjust PitchLinks to Correct Track to < .5 inch

Measure TrackSelect Midspeed Task & MeasureVertical Vibration

1

2

3Yes

No

Have all VibrationGoals been met?

Yes

Job CompleteRemove equipment and return aircraft to service.Congratulations!!

NoRepeat thisprocess asrequired

5

Main Rotor Track and Balance Procedure with MicroVib II

Land Aircraft and evaluatedata. Is mid speed and highspeed vertical vibrationwithin limits and all trackless than 1/2 inch

Make tab or P/L moveand enter it into unit,both Mid speed and High speed tasks

Dynamic Solutions Systems Inc.

Measure Ground Track & Gnd Lat

Read Safety statement

Is Ground Track < .5 inch? No

Yes

4Evaluate data. Decideif P/L or Tab move isbest choice

Be sure Lateralwt sens and tachfactors are right

Make sweep orweight move perMicroVib II

Enter moveinto MicroVib II

Hover Aircraft

Measure HoverLateral Vibration

Is Hover Lateral < .2 IPS? No

Yes

6

Revised 2-1-07

Is Gnd Lat < .3 IPS? No

Yes

Make sweep orweight move perMicroVib II

Select HoverLateral Task

Select GND Task

Evaluate data.Is Lat. vibration <.4 IPS. Is Track <.5 inch?

Yes

No

Also if you are working the pitch link andmidspeed solution is radically different from thehigh speed solution, you should implement thesolution for midspeed and then go on to tab toresolve the high speed vibration.

Alternately, if you are working the tab and themidspeed solution is radically different from thehigh speed solution, you will probably need to splitthe difference to keep the vibration at both speedswithin spec.

When shifting from p/l to tab moves, you shouldonce again make the first tab move based on trackdata only, and enter the move into the MicroVib II.After the next flight, the Microvib II will present asolution in terms of tab.

Remember, perfect visual track and minimumvibration only occur simultaneously with perfectblades. There are no perfect blades. You will findit is common for blades to be slightly out of trackwhen minimum vibration is achieved. It is a verycommon mistake to achieve good vibration levelsand then make one final tab move to sharpen up thevisual track, only to find the vibration is now out ofspec. You will almost never have both perfectvisual track and minimum vibration, you mustchoose one or the other as a goal. We recommendyou aim for minimum vibration and not beconcerned about a small out of visual trackcondition (1/2 inch).

Decision 5 and 6

Experience has shown that a moderate amount(.3-.6 IPS) hover lateral can be corrected with bladesweep or adding weight at the end of the process.This correction will not change the track or forwardspeed vertical vibrations.

Ground Rock

It is common to correct the hover lateral and findthat you now have a “ground rock” or groundlateral vibration. This can be caused by unequaldampers on articulated rotors. It is possible to uselead-lag data to find the damper that is causing theproblem. Just take a lead-lag reading at 100% onthe ground and compare it to a lead-lag reading inhover. Ideally the two readings will be identical,

but if not, you can see which blade is moving out ofthe pack. If you choose to live with the existingdampers, you can equalize the vibration betweenground and hover by producing a solution for bothand then splitting the difference.

Common Myths about Pitch Link Adjustments

It is a commonly held belief that pitch links shouldbe adjusted to produce flat track on the ground ateither 65% or 100% and then LEFT ALONE.Experienced mechanics have taught us that this is amyth. The pitch link ground adjustment should bethought of as just a coarse setting and the mid andhigh speed track and vibration data may indicatethat the pitch link should be fine tuned for forwardflight. The key relationship to remember is that thepitch link will effect track at hover, mid speed andhigh speed in gradually increasing amounts, whiletab will only effect mid speed track moderately andhigh speed track strongly. We have found thatstarting out with minimum tab and pitch linking toget the mid speed track and vibration good willleave only a small tab move required to finish therotor. This will put the hover and ground trackslightly out, but this is not crucial and hoververtical vibration is very low under theseconditions.

Why? Our theory is that blades only show their truecolors when loaded up. The dynamic loading ofhover and flight will show up a pitch link thatneeds to be adjusted even though it was "perfect"on the ground. The alternative is to try and put alarge tab adjustment in to correct the small pitchlink error. This condition will be accompanied bydata that shows more tab will improve track, butmake vibration worse. This is often accompaniedby a mechanic who claims "these blades just won'tfly together".

This procedure covers the basics for all standardtype helicopters, but each type has unique traits.See our app notes for tips and hints on each type ofhelicopter.


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2-18

Wait for5+ Avgs

Implementsolution onaircraft

Enter Actualwt/move amountand angle

OnKey

AvgKey

SaveKey

ENTERCHGS

BalanceScreen

SolutionScreen

TaskKey

StartAnalysis

Gathering Balance Data In Flight

Look for amber LEDon tracker

Aim trackerto get green LED on.

Pull triggeron tracker and release

Keep GreenLED on untilamber LED lights

Rotor Tracking Screen

Rotor BladeTracking

SaveData

Enter file nameor accept auto-generated name.

OK

Gathering Track Data in Flight

Implementing Balance Solutions on Ground

OnKey

SolutionScreen

Split solutionif required

Note actualweights/movesused on note pad

OnKey

SolutionScreen

SolutionScreen Repeat for other tasks

ChangingTasks

PickTask

Enter weight moves in grams. + = add, - = removeEnter Pitch Link moves in flats + = up, - = downEnter tab moves in degrees + = up, - = down.Enter sweep moves in flats + = fwd, - = aft.

TRACKOPTS

Set number of bladesDisplay Lead-LagSet Track distanceSet number of revsSet Metric Units

Tracker Setup

Select Task Screen

StartAnalysis

Rotor Tracking Screen

ModeKey

ControlPanel

MicroVibControl Panel Screen

New History File

Select Group Screen

Pick a Templateor Group File

Enter HistoryName Screen

OKKey

ModeScreen

Getting Started

Chapter 3 Spectrum ModeThe Spectrum Analysis mode of the Microvib IIdisplays a spectrum plot of the input signal. Aspectrum plot shows the vibration amplitude vs.frequency on a graph. To accomplish this we usethe FFT algorithm. The FFT algorithm divides upthe current frequency range into 50, 100, 200, 400or 800 bins. Each bin is a narrow band filter. It isimportant to understand that the bin frequency isnot the same as the signal frequency. Many FFTanalyzers only provide the frequency andamplitude of each bin and cannot accuratelymeasure the actual signal frequency and amplitude.The MicroVib II provides a Peak Locate algorithmthat calculates the actual signal frequency andamplitude using the known relationship betweenbin values and the signal.

In addition to the spectrum plot, the displayprovides additional information pertaining to theinput signal and spectrum as described below.

3.1 On Screen Data1. Full-scale amplitude level on spectrum plot

2. Graphically represents the available signaldynamic range and current peak input signalwith a 0 to full scale bar graph.

3. Shows the Data Units and the UnitsType.

4. Indicates the ACTIVE or FREEZEdisplay status.

5. Indicates frequency units - Hz orCPM.

6. Indicates the Max and Minfrequency of the current spectrumplot.

7. Indicates the frequency andamplitude at the current cursorlocation.

8. Indicates the cursor mode.

9. Indicates the window type.

10. Indicates the number of bins

11. Optionally can show time and date on screen

12. Shows current task and sensor selection

13. Shows current charge status of battery.

14. Indicates if data averaging is on or off.

3.2 Function KeysThe analyzer's function keys provide the followingactions in spectrum mode.

The AVG DATA key enables and disables theaveraging function. The maximum number ofaverages can be set using the SPEC OPTS key.

The CLEAR SCREEN key empties the data bufferand starts the autorange process over again. If theunit is averaging, this key empties the currentaverage data buffer and starts the averaging processover.

The LEFT and RIGHT arrow keys position thecursor to the frequency of interest on the spectrumplot. You may press the key once for anincremental cursor movement, or press the key andhold to continuously move the cursor across theplot. The cursor status and present frequencylocation and amplitude are indicated at the top ofthe plot.

Chapter 3 Spectrum Mode

3-1

OPTS

1

3

2

6

7 1112 8

5 10

134

69 14

The < > EXP key zooms in the view and centers iton the current cursor location. This is useful toexamine several tightly bunched spectral lines.

The > < DEC key zooms the view back out to see alarger range of bins.

The START STOP key freezes the display forcloser analysis or to file or print the spectrumshown. Press the key again to return to live mode.

The UP and DOWN ARROW keys changeamplitude full scale value of a spectrum plot. Thisis to get a better view of smaller signals in thepresence of a large signal.

3.2.1 Cursor Modes

The CURSR MODE key activates additionalcursor modes that can be used to identifyfrequencies more accurately within the spectrumplot. Press the CURSR MODE key repeatedly tostep through the five modes described below. Thefour cursor "on" modes are indicated at the top ofthe display.

Cursor Off - Cursor is not displayed on the screenand the cursor mode indication is blank.

Cursor On - The cursor is always placed on anactual FFT bin and the cursor detail will show theactual FFT bin amplitude and frequency. Thismode is indicated by a square crosshair cursordepicting the bin location. It is important toremember that the FFT bin frequency andamplitude are not the same as the incomingsignal frequency and amplitude.

Peak Locate - The cursor position and cursordetail are interpolated between adjacent bins inorder to show the actual vibration peak amplitudeand frequency. The Peak Locate mode should beused whenever high accuracy vibration amplitudeand frequency are desired. This mode is indicatedby a round crosshair cursor depicting the actualvibration peak. Note: The interpolation algorithmwill sometimes be unable to discern the peak valuebased on adjacent FFT bins and will be shown asthe square crosshair as described in the Cursor Onsection above.

Harmonic - This cursor mode will display thepreviously described Peak Locate cursor along withup to 16 harmonic markers. Harmonic markers willbe round only if the harmonic peak can beinterpolated by the peak locate algorithm andsquare if not. The harmonic markers are locked inposition when this mode is entered and moving thecursor will not change their locations.

Move Harmonics - This mode marks theharmonics just as the Harmonic mode did, but inthis mode, when you move the cursor, all theharmonic markers move with the cursor. Anytime aharmonic marker lands on a peak, its shape willchange from square to round.


File - This key provides access to the FileDirectory Screen.

Task - This key allows you to select the task. Tasksetup is only available in Balance Mode.

Help - This key provides information about thecurrent function.

Save Plot - This key will save the current screen. Itwill prompt you to enter a name for the plot file, oryou can simply accept the automatically assignedname.

SPEC OPTS key is described in the next section.


3-2

3.3 Spectrum OptionsThis key takes you to a screen where you canadjust the way the Spectrum mode works. Thefollowing selections and changes can be made:

3.3.1 Frequency Ranges & FFT Bins

Set Frequency Range and Number of Lines -This screen allow you to pick from 50-800 lines ofresolution and from 250Hz thru 20KHz Fmax.

Set Minimum Frequency - This screen allows youto enter the minimum frequency you want todisplay on the screen. Moving the cursor left willoverride this limit when desired. The lowest binfrequency is always Fmax/Number of lines, so youcannot go below this frequency in any case.

3.3.2 Trigger Setup

Set Trigger - This key leads to a menu of optionscalled Trigger Settings. TACH TRIGGER willsynchronize the data collection to the tach input.AUTO TRIGGER will attempt to automaticallysynchronize the data collection to the incomingsignal. LEVEL TRIGGER allows the user to set asignal level that will initiate data gathering. SETTRIGGER LEVEL presents a data entry screenfor setting the trigger level in display units.Entering zero for the trigger level will cause theunit to automatically set the trigger level to 25% ofthe input signal range. SET TRIGGER DELAYleads to a data entry screen where the user canenter a time delay (in milliseconds) between thetrigger event and the start of data collection.MAXIMUM INPUT presents a data input screenwhere the user can disable the autorange functionand set the full scale range to a fixed value.Entering zero enables autoranging.AUTO-REPEAT will start a new data gatheringcycle on the next trigger after the data has beendisplayed. In SINGLE SHOT mode, the unit willtrigger once and then hold the data, ignoringsubsequent triggers until START/STOP key ispressed.

3.3.3 Display Units & Units Type

Set Display Units - This screen allows you toselect the units of the vertical scale on the

spectrum. Sensor units, Accel units, Velocity units,Displacement units, Metric units, Log Scale, dBunits. It also allows you to select the units type:RMS, Peak, Average or Pk-Pk.

Advanced Options - See next section.

3.3.4 Averaging Setup

Maximum Number of Averages - This screenallows you to select the number of averages youwant the unit to take before it terminates averagingand starts a new average. You can enter a value ofup to 99.

Average Type - Three keys: Linear, Exponential,or Peak Hold allow you to select what kind ofaveraging the unit will use.

Linear averaging is simply adding all the data upand dividing by the number of averages. The unitwill count up to the Maximum Number ofAverages and then automatically start over. Thenumber of averages is displayed on the screen inthis mode.

Exponential averaging is more of a “smoothing”function that provides more weight to recent dataand assigns a lower weight to older data as timepasses. The screen indicates EXP for this mode.

Peak Hold Averaging is not really averaging atall. In this mode the unit records the highestreading each bin has received since the PEAKHOLD key was pressed. This mode is useful formonitoring turbine engine spool-ups to see if anyrotor in the engine is going through a seriously hightransient vibration as the shafts pass throughcritical speeds.

Advanced Options

3.3.5 Flat Top, Hann or Rect Window.

A window function is a mathematical processwhich is applied to the sampled vibration databefore it is converted from the time domain(waveform) to the frequency domain (spectrum) viathe Fast Fourier Transform (FFT). A windowfunction is applied to the data in order to reduceundesirable effects of the sampling process in thecomputed spectrum. These "real world" effects are


3-3

caused by sampling discontinuities whichunavoidably occur at the beginning and end of thesampling period. The user can optimize theperformance of the spectrum analysis function for aparticular job by selecting the most appropriatewindow function for that job.FFT windows are basically compromise functionsbalancing the need for amplitude accuracy and theability to resolve the frequency value accurately.Fundamentally the window function determines theshape of each of the 400 or 800 etc filters in theFFT spectrum.

The Flat Top window provides a slightly widerbandwidth compared to other windows but thehighest amplitude bin will always be very close tothe actual amplitude of the signal. This moreaccurate amplitude value comes at the price oflower frequency resolution. That is, the displayedbin value data will not show you clearly what theRPM of the signal is. There will be at least twoadjacent bins with virtually the same amplitudevalue, so from these bin values alone, you will notbe able to determine what the frequncy of thesignal is with much resolution. This also means thatif you are trying to see sidebands near a peak, theywill probably not be visible with this window.

The Hann Window (aka Hanning Window) is muchnarrower when compared to the Flat Top window.One bin will usually be the highest in amplitude,and this will be a pretty accurate measure of thefrequency of the signal. However, even the highestbin value will be less than the true amplitude of thesignal. This window is good for giving you anaccurate picture of sidebands around a peak, whilecompromising the amplitude accuracy.

Rectangular Window (aka Boxcar Window or “No”Window). This window provides a filter shapewhich is even narrower than the Hann window nearthe peak of the signal, but the skirts of the filter arenot very steep out away from the peak. Thiswindow will tell you you have some energy 10%away from the actual signal value, when there is noenergy there at all. This is only true withcontinuous signals however. It is not true if thesignal itself is a transient type of signal. Thiswindow is actually the best choice for transient

type signals like hammer tuning as it provides thebest frequency resolution of all.

The Peak Locate cursor function of the MicroVib IIcorrects several of the compromises of each ofthese windows. It looks at the value of the adjacentbins near the peak of a signal and then determinesboth the exact amplitude and frequency of thesignal itself. Thus eliminating most of thedrawbacks associated with the compromisesmentioned above. It is for this reason we use theHann window as the default window type andprovide the peak locate function to determine exactamplitude and frequency values.

3.3.6 Show Overall

When “Show Overall” box is dark, the spectrumscreen will be annotated with the overall vibrationlevel in the upper right corner of the data area.Overall is an algabraic sum of all the displayed peaks in the spectrum. (default is on). The overallfunction can be used to measure the broadbandvibration amplitude between any two frequenciesby setting an Fmin and an Fmax. This allows theMicroVib II to provide readings of enginevibrations equivalent to very old vibrationinstruments used for turbine engine testing.

3.3.7 10 Hz High Pass Filter

This option puts a 10 Hz high pass filter in thesignal path. There are many cases where therandom low frequency vibration data is very largecompared to the vibration of interest. Engaging thisfilter will greatly improve signal to noise ratio inthis case and you will be able to make moreaccurate low level readings. Aircraft aerodynamicturbulence is dominated by low frequency randomvibrations. (default is off)

Note: This high pass filter should neverbe used on Helicopter Main Rotor work.


3-4

3.4 Spectrum Procedures This section covers vibration spectrummeasurement only.

Taking a Spectrum

The following procedure assumes you haveproperly mounted the vibration sensor securelyusing an appropriate bracket and have routed thesensor cable and connected it to the MicroVib II.

1. Operate the engine for a minute or so to warmit up to normal operating temperature.

2. Operate the engine at the RPM of interest andpress the ON OFF, MODE, SPECTRUMANALYSIS, and START ANALYSIS keyson the analyzer.

3. Press the AVG DATA key if an average isdesired.

4. After the averaging is complete, or when thedata appears valid, press the START STOPkey to freeze and analyze the data.

5. Press the SAVE PLOT key to store thisspectrum plot in memory. You will beprompted to name the plot or accept theauto-generated name.

Note: We recommend you take aSpectrum reading before and after youbalance any rotor and keep theserecords in MicroBase for futurereference.


3-5

Chapter 4 Waveform ModeThe waveform mode displays the amplitudeof the input signal versus time rather thanversus frequency. This is useful under certainspecial conditions. For the most part it is usedin the same way an oscilloscope is used toexamine any kind of signal.

4.1 On Screen DataThe Waveform Analysis screen provides thefollowing on-screen information

Task Name - Selectable using the Task Key.Task names can only be changed in theBalance mode, Task, Task Setup screen

Sensor channel - Selectable by selecting tasks.Sensor channel assignments can only bechanged in the Balance mode, Task, TaskSetup screen.

Full scale A-D range and current peak valueof signal in bar graph form.

Full scale Amplitude Value

Display Units - Default type is Accelerationin G. Velocity, Displacement or Sensor unitscan be selected in Wave Options.

Time Axis - Provides start time and end timeof the data block.

Time units - Milliseconds

Points - Number of data points in the datablock.

Sample Rate - Rate at which the data wassampled. Units are Sample/Sec.

Time and Date - Optionally selected in thecontrol panel.

Battery Voltage and Bargraph.

4.2 Function KeysThe waveform analysis screen provides thefollowing function keys:

Mode Key - Allows user to select othermodes

File Key - Allows user access to the filedirectory

Task Key - To change tasks.

Help Key - Provides information about thecurrent function.

Wave Options - This key is described in thenext section.

Save Plot Key - Used to save the currentwaveform plot to disk. User is prompted toenter a name if desired or the automaticallyassigned name will be used.

Anti-Alias Key - In waveform mode, thedefault setting has the Anti-Alias filter off(Bypassed). By pressing this key you can putthe anti-alias filter in the signal path.

Clear Screen - Erases the data buffer andstarts over.

Start-Stop Key - Freezes the screen. Usefulwhen printing or saving a screen.

< >EXP Key - Zooms in on the waveform toget a closer view of a time space.

> < DEC key - Zooms out to get a wider viewof the data.

Cursor Mode - Scrolls thru the followingCursor Modes:

Cursor Off - No cursor shown

Cursor On - Turns on cursor and displays thetime and magnitude of the signal at the cursorlocation. Left and Right arrow keys allow youto position the cursor in time.

Chapter 4 Waveform Mode

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Delta Cursor - In Delta Cursor Mode, thecurrent location of the cursor becomes thefirst cursor location. By using the right or leftarrow keys the Delta cursor may bepositioned independently of the first cursor.Along the top edge of the screen will bedisplayed DT which the time differencebetween the first cursor and the delta cursor, Fwhich is the frequency that would correspondto DT (F=1/DT) and DM which is theamplitude difference between the two cursors.DM is useful if you are trying to position thedelta cursor at the same amplitude on the nextcycle of the signal

4.3 Waveform OptionsThe Waveform Options key provides a meansto control the way the Waveform modeworks.

Set Sample Rate and Number of Points:You can select sample rates of 1024 Hz, 5120Hz, 25.6KHz, and 51.2 KHz. You can select128 thru 2048 points in four binary steps. Thedata can be put through an anti-alias filterbefore sampling to prevent the waveformmode from displaying false alias signals. SeeSection 4.2. The anti-alias filter will removehigher frequency components of any signal,which will often appear to be introducing“ringing” distortion of sharp edged signals.

Set Display Units - This screen allows you toselect the units of the vertical scale on thedisplay. Sensor units, Accel units, Velocityunits, Displacement units and Metric units.

Set Trigger - This key leads to a menu thatallows you to setup how the unit triggers thedata capture. See section 3.3 Set Trigger.

600 CPM (10Hz) Min Freq - If this key isdark, a 10 Hz high pass filter is in the signalpath. Default is off. Aircraft vibrations areoften dominated by very low frequencyrandom noise caused by aerodynamic forces.In order to see the vibrations of interest, it isoften helpful to filter out these very highamplitude low frequency signals.

120 CPM (2Hz) Min Freq - If this key isdark, the 10 Hz high pass filter is bypassed,allowing viewing of very low frequencysignals down to the lower input limit of 2 Hz.This is the default setting.

Chapter 4 Waveform Mode

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Chapter 5 Tach RatioThe tach ratio display provides a display ofactual rotor or engine rpm even when the tachgenerator runs at a different speed than thetarget rotor. It also provides a display of%RPM once the user has specified the 100%RPM of the target rotor or device.

5.1 On Screen Data The Tachometer Rate screen provides thefollowing data on screen.

Target Speed in %RPM Digital Readout

Target Speed in %RPM in Analog BargraphForm with 110% max.

Actual RPM of the Target, Digital ReadoutRPM or Hertz (RPM or Hz is selected fromControl Panel)

Actual Input signal rate in RPM (RPM only)

User Entered 100% RPM of Target. (RPMonly)

Task Name - Selectable using Task Key

Tach Sensor Channel - Selectable via task.Task Sensors can only be changed fromBalance Mode, Task, Task Setup screen.

Time and Date - Optionally as selected inControl Panel.

Battery Voltage and analog bargraph ofbattery energy remaining

5.2 Function KeysThe Tach Ratio Mode provides the followingfunction keys:



Task - This key allows you to link any savedscreens to particular tasks.

Help - This key provides information aboutthe current function.

Tach Options - This key is described in thenext section

Save Plot - This key will save the currentscreen. It will prompt you to enter a name forthe plot file, or you can simply accept theautomatically assigned name.

Avg Data - This key will engage exponentialaveraging of the Tach data. This will smoothout any rapid changes in the tach rate display.

Clear Screen - This key clears the data bufferand starts the measurement over.

Start Stop - This key freezes the screen.Useful for printing or saving a screen plot.

5.3 Tach OptionsThis key leads to a screen where you cancontrol how the Tach Rate function operates.

Set Input RPM - Enter the 100% RPM of theTach Generator. If the tach signal is 1 pulseper rev of the target rotor, then this value isthe same as the 100% RPM of the target rotor.Normally the signal out of the tach generatorwill not be at the same rate as the target rotor.

Set Target RPM - Enter the 100% RPM of thetarget rotor. This is the rotor you areinterested in. The large bargraph will bedisplaying the RPM of this rotor.

If you only know the 100% RPM of theTarget Rotor and the Gear Ratio of the tachgenerator to the Target rotor, you cancalculate the 100% RPM of the generatorusing simple math.

Chapter 5 Tach Ratio

5-1

Chapter 6 Optical TrackingBlade Tracking is the process of measuringthe physical location of the blade tips whenthe rotor is turning. It isimportant to remember thatzero blade track does notnormally coincide with equalblade loading. Our goal inmeasuring blade track is not tominimize blade track, butrather to minimize verticalvibration which does coincidewith equal blade loading. Weuse the track information tohelp us decide which bladeneeds an adjustment, but ourgoal is always minimumvibration and not minimumtrack.

The MicroVib II supports twomethods of blade tracking:Optical Tracking and StrobeTracking. The selection of which type oftracking is done is made by the kind of MUXunit that is connected to the MicroVib II.Tracker MUX PN 1450 and MicroTrack PN1145-X are used to perform optical bladetracking. Strobe MUX PN 1680 and acompatible strobe are used to perform strobeblade tracking.

In either case, to access the Blade TrackingMode from any analysis screen press theMODE key, press the ROTOR BLADETRACKING key and press STARTANALYSIS.

6. 1 On Screen DataOptical Track Mode provides the followingon-screen data

1. Graphical Display of Track Data: Data isrelative to the average of all blades. Ifdata goes off screen, a bold arrowheadwill indicate data is off-screen

2. Screen Title.

3. Task Name: The current task name isdisplayed. This name is user definable.

See task setup to name the task

4. Current Date - Optional See 1.10.12

5. Current Time - Optional See 1.10.12

6. Battery Status Indicator - Digital readoutof voltage, bargraph of battery energyand charging status.

7. Current history file name or saved plotfile name.

8. Freeze/Saved Indicator: This is a small indicator that indicates FREEZE after thedata gathering is complete. It indicatesSAVED when a screen has been recalledfrom disk.

9. Status Indicator Area - This part of thescreen will indicate “READY FORTRIGGER” when the unit is ready to

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gather track data. It will indicate“PROCESSING TRACK” while the unitis gathering track data. It will indicate“TRACKER DISABLED” when viewinga saved plot.

10. Tach Channel Indicator - The currenttach channel is shown here. The tachchannel selection is made in the TaskSetup (Sec 2.9.1). When a track screen isrecalled from disk, the tach channel usedwhen the data was collected is displayed.

11. Group File Name - The group file nameis shown here. The group file name isselected as part of creating a new historyfile. (See Sect 2.8.5)

12. MUX Indicator - If a MUX unit isconnected, this indicator will show it.

13. Digital readout of blade track amplitude.The difference between the highest bladeand the lowest blade.

14. Number of Revs: The number of revs ofdata that will be collected before the datais displayed. This value is user selectablein the Track Options screen.

15. Track full scale amplitude at top ofdisplay.

16. Lead Lag full scale amplitude.

17. Track data unit of measure - Userselectable to inches or mm in TrackOptions screen.

18. Digital Readout of Lead Lag Amplitudein degrees peak to peak.

19. Track full scale amplitude at bottom ofdisplay.

20. Lead Lag Reference Blade - Rectangularbox indicates which blade is being usedas the reference blade for Lead Lagcalculations. User selectable with Rightor Left Arrow.

21. Blade Number - The blade identified asnumber 1 in the track display is the bladewhich is positioned closest to the point atwhich the MicroTracker is pointing whenthe rotor is static (non-turning) and thephoto-tach is aligned with the reflectivetape. Blade order is defined as the orderin which the blades pass a particularpoint on the disk. Blade 2 is the nextblade to pass after blade 1.

22. Blade height indicator - Provides a visualdisplay of the blade height.

23. Lead Lag Indicator - Provides a visualdisplay of lead lag data. Leading bladesare shown to the left and lagging bladesare shown to the right.

24. Digital Readout of blade lead or lag ascompared to the reference blade. Leadlag data can be turned on or off in theTrack Options screen.

25. Camera to Blade Tip distance. Thedefault value is 200 inches. User canenter this value in Track Options. Unitsare fixed as inches.

26. Digital Readout of Rotor RPM. This datais derived from the tach signal.

6.2 Function KeysThe Rotor Tracking Screen provides thefollowing function keys:

Mode - This key allows you to change modes.

File - This key provides access to the FileDirectory Screen. (See Section 1.13)

Task - This key allows you to select the taskor setup the tasks as explained in section 2.9.


Track Opts - Track Options: This key isdescribed in the next section


6-2


Live Data - This key will enable on-screenlive display of blade track data as it is beinggathered. This mode is not normally used asyou must aim the tracker.

Clear Screen - This key will empty the databuffer and start the process over.

Start (TRG) - This key performs the samefunction as the trigger button on the trackercamera unit. It is mainly useful when usingthe Tracker Simulator for training.

Start Stop - When viewing a saved track plot,this key will terminate viewing and return theunit to live mode.

Arrow Keys - The amplitude scale can bechanged with the Up and Down arrows. TheRight Arrow key changes the reference bladefor Lead-Lag measurement.

6.3 Track OptionsThe Track Options function key leads to theBlade Tracking Options screen. From thismenu, you can setup the tracker to match thehelicopter in use.

6.3.1 Number of Blades

You must enter the number of blades for thetracker to work properly. Keys are availablefor 2, 3, 4 or 5 blade rotors. If you have morethan five blades, press the ENTER NUMBERBLADES key and enter a number from 2-7.

If you enter the wrong number of blades, theunit will indicate *** INVALID DATA ***Check Number of Blades.

6.3.2 Display Lead Lag

This key will enable the display of lead lagdata. Lead Lag data is normally displayedrelative to the average of all blades, but bypressing the Right arrow key, you can select a

reference blade. Lead/Lag full scale range isautoranged, and is not adjustable.

6.3.3 Set Track Distance

Press the SET TRACK DIST key to set theTrack Distance. This is the distance from theMicroTracker's position to the ends of therotor blades in inches. The Track Distance isused to calculate the track sensitivity. Forexample, entering a larger Track Distance willcause the unit to compute larger blade trackdifferences (blades will appear farther apart).

6.3.4 Set Number of Revs

Press the SET NUMBER OF REVS key itemto set the Number of Revolutions to collecttrack data before updating the display. Thedefault Number of Revs is 32. At 400 RPM,32 revs will take about 10 seconds to collect.

6.3.5 Metric Units

The Metric Units key enables the display oftrack amplitude in mm instead of inches. Thiskey is dark when Metric is selected.

6.4 Equipment SetupFor the tracker to work, you have to satisfy anumber of requirements.

6.4.1 Tach Signal

A once-per-rev signal from the main rotormust be provided. This can be from aphotosensor, magnetic pickup or similardevice. This signal must be connected to aTach Input on the MUX unit. Normally TachA. This is the same signal required to balancethe main rotor

6.4.2 Adequate Light Level

Normally, as long as the sun is up, even on avery cloudy day, the light level will beadequate. You can check the light level byaiming the tracker up into the rotor blades andconfirming that the upper red LED’s light. Ifyou can’t get the upper RED led’s to light up,the light level is too low.


6-3

6.4.3 Background

The background you are aiming the trackerinto must be the sky. Blue sky or clouds. Ifyou are on the ground and aiming into ahangar wall or a nearby tree, the tracker willnot work. Trying to track with the aircraftdiving so the background is the ground willnot work either.

6.4.4 Aiming the Tracker

You must aim the MicroTracker at the correctpoint on the rotor disc for the system toidentify the blades correctly. To do this youmust first position the rotor statically on theground with the phototach or mag p/u alignedwith the retro-tape or interrupter. Thisposition we call the “static position”. Nextyou must decide which blade will be theeasiest to point the tracker at in flight. This isusually the blade over the nose in the “staticposition”. You must point the tracker at thisblade location when gathering track data. Ifyou point in any other location, you willscramble the sequence of the data. The bladeyou are pointing at in the “static position”becomes by definition the number one bladein the data display on the screen of theMicroVib II. The next blade to come by intime is by definition the number 2 blade andso on. See Figure 6-1

6.4.5 Tracker Location

The tracker itself must be located properly forthe tracker to work. The tracker must bewithin 15 degrees of the line from the bladetip to the mast. See Figure 6-1.

6.4.6 Orientation to the Sun.

Once the sun is 30 degrees or more up in thesky, you must avoid pointing the trackertoward the direction of the sun. Shadows ofthe blades can strike the front of the trackerproducing false signals. On the other hand,toward the end of the day, as the sun issetting, the sky will be sufficiently bright if

you aim the tracker more toward the sun. Youshould verify that you can get the upper redLED’s to light when working at the end of theday. This is done by pointing the tracker just alittle too high and the red led’s should comeon.

6.4.7 Holding the Tracker

One mistake users make is holding the trackervery rigidly and even bracing against abulkhead or placing the elbow on the knee asa brace. What you must keep in mind is thatyou are trying to isolate the tracker from theaircraft using your arms as a kind of softsuspension. So relax a bit and hold yourelbows out away from your body so they canwork freely and easily. Use both hands.

6.4.8 Clean the Canopy

If the window or canopy the tracker is aimedthru is dirty, this dirt can pick up shadows ofthe blades and introduce false signals. Be sureto clean the canopy before the flight.

6.4.9 Blade Color

The most ideal condition for the tracker is forthe last 6 feet of each blade bottom to beuniformly flat black. The worst condition iswith the blade bottoms painted white oryellow, very bright ground color (like sandydesert) and very deep blue sky. Also it isimportant that the blades be uniform in colorfrom blade to blade. Also, if only the bladetips (last 2-3 feet) are much darker or lighterthan the rest of the blade, this can causeproblems.

6.4.10 Equipment Hookup

The MicroTracker plugs into a dedicated 15pin connector on the PN 1450 MUX unit. TheMUX unit plugs into the MicroVib II.


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6-5

Retro-tapeor Interrupter

Photo-tachor Mag P/U

Static Position

Blade #2

TrackerTracker

Aiming Zone

Tracker LocationZone

RotationCW

Figure 6-1

Step 1Position rotor with phototach aligned with retro-tape or mag pickup aligned with interrupter. This is the "static position".

Choose this blade. It then is Blade #1

Step 2Choose which blade you are going to aim at.

Step 3You must aim the tracker in this narrow zone

Step 4Tracker must be located within 15 degrees of tip to mast axis.

6.5 Tracking Procedure1. Setup equipment per section 6.4 above.

2. Operate the aircraft rotor at desiredRPM.

3. Turn on MicroVib II. Press MODE keyand select ROTOR BLADETRACKING and START ANALYSIS.

4. MicroVib II screen should say “Readyfor Trigger”.

5. Press TRACK OPTIONS and verifyNumber of Blades, Track Distance, andNumber of Revs are correct. PressSTART ANALYSIS to continue.

6. Grip the handle of the MicroTracker withtwo hands and hold it up in front of yourface with your arms away from yourbody. Suspend the tracker with yourarms to help isolate it from aircraftvibrations.

7. Notice the bargraph display on the backof the MicroTracker. Verify the YellowLED at the bottom of the bargraph isON.

8. Aim the MicroTracker at the correctazimuth location and aim it up and downto get the green LED’s in the bargraph tolight up. .

9. When the bargraph is in the Green,momentarily pull the trigger switch onthe MicroTracker and release it.

10. You will notice the yellow LED begin toblink once per revolution. Keep thebargraph in the green as best you canuntil the yellow LED comes back onsteady.

11. View the Rotor Tracking Screen andverify the data looks OK and the RPM iscorrect. Press the SAVE PLOT key tostore the data. You can name the dataplot or just let the MicroVib II give it a

name. The data will be annotated withthe current task name and time for easyidentification. Press OK

12. The screen you just saved will now be onthe screen and the SAVED indicator willbe shown and the status indicator willshow “Tracker Disabled”. Press theSTART STOP key to return to livemode. The data will disappear and the“Ready for Trigger” status will beshown. Now you are ready to gathermore track data.

MD500 Note;

It has been found experimentally that theMD500/600 track data is most accurate whenthe Track Distance is set to 50.


6-6

6.6 Tracker ConfigurationsPN 1145 - Original Version.

PN 1145-1 - Improved low light levelperformance.

PN 1145-2 - Improved stability under brightlight conditions. All original and -1 unitsshipped were recalled and upgraded to -2 .

PN 1145-3 - Special OEM version.

PN 1145-4 - Minor change to allow use ofceiling fan for training and simulations.

PN 1145-5 - Improved accuracy over a widerrange of camera azimuth locations.

The -5 version requires a change to themating MUX box firmware. Once the MUX isupgraded to this newer version, the MUX willno longer work with previous versions oftrackers.

Older trackers can be upgraded to becompatible with the new MUX firmware.

Older MUX units can be upgraded to latestfirmware also.

MUX firmware is identified with MicroVib IIin the System Parameters screen. Display willshow Tracker-D for new firmware and justTracker for older firmware.


6-7

Chapter 7 Strobe TrackingBlade Tracking is the process of measuringthe physical location of the blade tips whenthe rotor is turning. It isimportant to remember thatzero blade track does notnormally coincide with equalblade loading. Our goal inmeasuring blade track is notto minimize blade track, butrather to minimize verticalvibration which doescoincide with equal bladeloading. We use the trackinformation to help us decidewhich blade needs anadjustment, but our goal isalways minimum vibrationand not minimum track.

The MicroVib II supportstwo methods of bladetracking: Optical Tracking and StrobeTracking. The selection of which type oftracking is done is made by the kind of MUXunit that is connected to the MicroVib II.Tracker MUX PN 1450 and MicroTrack PN1145-5 are used to perform optical bladetracking. Strobe MUX PN 1115-1 and acompatible strobe are used to perform strobeblade tracking.

In either case, to access the Blade TrackingMode from any analysis screen press theMODE key, press the ROTOR BLADETRACKING key and press STARTANALYSIS.

7. 1 On Screen DataStrobe Track Mode provides the followingon-screen data

1. Graphical Display of Track Data:Dominating the screen are several large

rectangular blocks that graphically depictthe track data as manually entered.

2. Screen Title.

3. Task Name: The current task name isdisplayed. This name is user definable.See task setup to name the task.

4. Current Date - this is optional as selectedin Control Panel. (1.10.12)

5. Current Time - This is optional asselected in Control Panel (1.10.12)

6. Battery Status Indicator - Digital readoutof voltage and bargraph of batteryenergy remaining along with chargingstatus.

7. Current history file name or saved plotfile name.

8. Update/Saved Indicator: This is a small indicator that indicates UPDATE everysecond or so as the RPM data is updated.It indicates SAVED when a screen hasbeen recalled from disk.

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9. Status Indicator Area - This part of thescreen will indicate “READY TO FIRESTROBE” when the unit is ready. It willindicate “TRACKER DISABLED” whenviewing a saved plot.

10. Tach Channel Indicator - The currenttach channel is shown here. The tachchannel selection is made in the TaskSetup (Sec 2.9.1). When a track screen isrecalled from disk, the tach channel usedwhen the data was collected is displayed.

11. Group File Name - The group file nameis shown here. The group file name isselected as part of creating a new historyfile. (See Sect 2.8.5)

12. MUX Indicator - If a MUX unit isconnected, this indicator will show it.

13. Digital readout of blade track amplitude.The difference between the highest bladeand the lowest blade as manuallyentered.

14. Track full scale amplitude at top ofdisplay.

15. Track data unit of measure - Userselectable to inches or mm in TrackOptions screen.

16. Track full scale amplitude at bottom ofdisplay.

17. Selected Blade - Rectangular boxindicates which blade is currentlyselected for data entry using the UP andDOWN arrow keys. User selectable withRight or Left Arrow.

18. Blade Number - Corresponds to tip targetnumbers when used.

19. Blade height indicator - Provides a visualdisplay of the blade height as enteredmanually.

20. Digital Readout of Rotor RPM. This datais derived from the tach signal. This area

is also used to indicate Tach status.When tach signal is first applied this willindicate “ACQ TACH”, if tach signal islost, it will indicate “NO TACH”. If tachsignal is too high in frequency it willindicate “HIGH TACH”.

21. Digital Readout of the height of theselected blade. This data is enteredmanually.

7.2 Function KeysThe Strobe Tracking Screen provides thefollowing function keys:

Mode - This key allows you to change modes.

File - This key provides access to the FileDirectory Screen. (See Section 1.13)

Task - This key allows you to select the taskor setup the tasks as explained in section 2.9.


Track Opts - Track Options: This key isdescribed in the next section


More Spred - This key will spread out the tiptarget images as viewed using the strobe.

Less Spred - This key will reduce the spreadof the tip target images as viewed using thestrobe.

Clear Spred - This key cancels the targetspread function and will superimpose all thetip targets at the same azimuth location asviewed using the strobe.


7-2

7.3 Track OptionsThe Track Options function key leads to theStrobe Tracking Options screen. From thismenu, you can setup the tracker to match thehelicopter in use.

7.3.1 Number of Blades

You must enter the number of blades for thetracker to work properly. Keys are availablefor 2, 3, 4 or 5 blade rotors. If you have morethan five blades, press the ENTER NUMBERBLADES key and enter a number from 2-7.

7.3.2 Double Images

This key will double the flash rate of thestrobe, which will put additional groups of tiptarget images half way between the normallocations.

7.3.3 Metric Units

The Metric Units key enables the display oftrack amplitude in millimeters instead ofinches. This key is dark when Metric isselected.

7.4 Equipment SetupFor the tracker to work, you have to satisfy anumber of requirements.

7.4.1 Tach Signal

A once-per-rev signal from the main rotormust be provided. This can be from aphotosensor, magnetic pickup or similardevice. This signal must be connected to aTach Input on the MUX unit. Normally TachA. This is the same signal required to balancethe main rotor

7.4.2 Azimuth Location

You must aim the Strobe at the correct pointon the rotor disc to see the tip target images.Aim the tracker at the point where blade 1 iswhen the photocell is aligned with theretro-reflective tape. You can also view thetrack at the locations of the other blades. You

can get an image of the tip targets at 3:00 and9:00 on a two blade ship by using the DoubleImages function key.

7.4.3 Equipment Hookup

The Strobe plugs into a dedicated 5 pinconnector on the PN 1115-1 MUX unit. TheMUX unit plugs into the MicroVib II.

A source of 24-28 VDC 3 amps must beconnected to the MUX unit to power theStrobe. Use DC Power Cable PN 1123 andrequired adapters to connect to ship DCpower.

7.5 Tracking Procedure1. Setup equipment per section 7.4 above.

2. Operate the aircraft rotor at desiredRPM.

3. Turn on MicroVib II. Press MODE keyand select ROTOR BLADETRACKING and START ANALYSIS.

4. MicroVib II screen should say “READYTO FIRE STROBE”.

5. Press TRACK OPTIONS and verifyNumber of Blades is correct. PressSTART ANALYSIS to continue.

6. Grip the handle of the Strobe firmly andhold it up in front of your face and sightjust over or to the side of the strobe at thetip target zone. Since the tip targets areretro-reflective, they will appear verybright if you sight close to the edge ofthe strobe housing.

7. Pull the trigger on the strobe handle todisplay the tip targets. They will appearsuperimposed or “stacked” on top ofeach other. Press the “MORE SPRED”key to spread out the images for easieridentification. Make a mental note of thetip target display

8. Using the right and left arrow keys andup and down arrow keys, you can record


7-3

the strobe image on the screen. When thescreen looks like your mental image,press the SAVE PLOT key to store theimage. You can name the data plot orjust let the MicroVib II give it a name.The data will be annotated with thecurrent task name and time for easyidentification. Press OK

9. The screen you just saved will now be onthe screen and the SAVED indicator willbe shown and the status indicator willshow “Tracker Disabled”. Press theSTART STOP key to return to livemode. The data will disappear and the“READY TO FIRE STROBE” statuswill be shown. Now you are ready togather more track data.

7.6 Notes

Track scale will automatically change when you manually enter a track value over fullscale. Scale will automatically change tominimum full scale level that the current datawill fit into. Full scale values of 2.5, 5, 10,and 20 inches are supported.

Lead/Lag data is not supported. User willhave to judge lead lag values from the tiptarget image directly.


7-4

Chapter 8 Scan ModesScan Modes provide a means of measuringthe total vibration level at the sensor. Incontrast with the Spectrum mode, whichprovides a detailed breakdown of everyspectral line detected by the sensor, the scanmode computes the total value of vibration atthe sensor in a meaningful way to give you asingle number that is proportional to thevibration.

8.1 Overall Scan The overall scan uses the spectrum data andsums the vibration for all spectral linesbetween the user selectable lower and upperlimit. The summation is the square root of thesum of the squares of all spectral lines.

On Screen Data

1. Bargraph of Overall Value

2. Digital Readout of Overall Value

3. Display Units and Units Type

4. Min and Max Frequency

5. Full scale value of Bargraph

6. Balance History Filename

7. Vibration Sensor Channel Number

8. Current task name

9. Date and Time

10. Battery Voltage and Bargraph

11. Bargraph of Dynamic Signal Range

Function Keys

The Overall Scan Mode provides thefollowing function keys:



Task - This key allows you to link any savedscreens to particular tasks.


Overall Options - This key provides access tomenu of options: Set Max Freq, Set Min Freq,Set Display units (Acc. Velocity,Displacement, Pk, RMS, Pk-Pk, Avg, Metric)Fast Update option and Averager type..


Avg Data - This key will engage averaging ofthe reading. This will smooth out any rapidchanges in the vibration level.

Clear Screen - This key clears the data bufferand starts the measurement over.

Start Stop - This key freezes the screen.Useful for printing or saving a screen plot.

8.2 True Peak HoldPeak Hold is a function often used to find thehighest level a vibration value reaches, even ifit is only a transient event. This mode doesnot use the Spectrum data, but ratherevaluates the time domain data directly usingthe built-in analog high pass filters andanti-alias low pass filters to limit thefrequency range

On Screen Data

1. Bargraph of Peak Value

2. Digital Readout of Peak Value


4. Digital Readout of RMS Value

5. Digital Readout of Crest Factor



Chapter 8 Scan Modes

8-1




11. Date and Time



Function Keys

The Peak Hold Scan Mode provides thefollowing function keys:

Mode, File, Task, Help, Save Plot, ClearScreen and Start Stop are the same as insection 8.1 above.

TRPK OPTS - This key provides access tomenu of options: 10 Hz Min Freq, 2 Hz MinFreq, EXP Averaging On or Off, 250 Hz MaxFreq, 1KHz Max Freq, 5KHz Max Freq, 20Khz Max Freq. Set Display units (Acc.Velocity, Displacement, Pk, Pk-Pk, Metric)and Fast Update.

Avg Data/Peak Hold - This key will engage averaging of the reading if EXP averaging isselected in the TRPK OPTS menu. This keywill enable PEAK HOLD if EXP averaging isturned off.

8.2 True RMS ScanTrue RMS is a function often used to find thetotal power in a vibration reading. This modedoes not use the Spectrum data, but ratherpasses the filtered time domain data to a trueRMS converter IC. The frequency range isdetermined by user selectable analog highpass filters and anti-alias low pass filters.

On Screen Data

1. Bargraph of RMS Value

2. Digital Readout of RMS Value







9. Date and Time



Function Keys

The True RMS Scan Mode provides thefollowing function keys:

Mode, File, Task, Help, Save Plot, ClearScreen and Start Stop are the same as insection 8.1 above.

TRMS OPTS - This key provides access to amenu of options: 10 Hz Min Freq, 2 Hz MinFreq, 250 Hz Max Freq, 1KHz Max Freq,5KHz Max Freq, 20 Khz Max Freq., SetDisplay units (Acc. Velocity, Displacement,Metric) and Fast Update.

Avg Data - This key will engage averaging ofthe reading. This will smooth out any rapidchanges in the vibration level.

Chapter 8 Scan Modes

8-2

SpecificationsPhysical Properties

Length: 8.25 inches (210 mm) (lessconnector)Width: 4.25 inches (108 mm)Depth: 1.7 inches (43.2 mm) less feetWeight: 36.8 oz. (1.04kg)

Environmental LimitsTemperature: 15 to 120 F (-10 to 50 C).Relative Humidity: 0 to 95%

EnclosureDust tight aluminum case.

Battery Power SourceNiMH Rechargeable. 7.2 volt nominal.3.7 A-hrsOperation time: 18-30 Hours ofcontinuous use depending on mode anduse of backlight, etc.Recharges in 4 hours with Charger PN1309Charger power 90-250VAC 50/60 Hz.

LCD DisplayDot Resolution: 240 Vert. x 320 Hor.Dot pitch .012 in (.3 mm)Viewing area 3.14 Vert X 4.13 Hor.(80mm Vert X 105 mm Hor )S/N 1001-2299 EL Backlight (Green)S/N 2300 fwd. LED Backlight (Orange)

Input/Output ConnectorSide-mounted 18-pin MS3112E14-18Sconnector provides access to allinputs/outputs and serial port forcommunication with peripherals and hostPC software.Mates with MS3116F14-18P connector.

Input Specifications

Sensor PowerA 2mA constant current power supplyinside the analyzer powers ICP typeaccelerometers and sensors. The powersupply provides 2 mA constant currentfrom a 20 volt source. +5V and -5V arealso available to power other types of sensors/strain gauges.

Input RangeUser selectable or auto range from 16volts pk-pk down to 160 mV pk-pkfull-scale;Minimum measurable level is .05mV. (With a 20mV/g accelerometer at 100 Hz,the input ranges are 0-400 G; 0-250 IPS;and 0-800 mils.)

Dynamic Range72dB from full scale level.

AC Input CouplingLess than 2 Hz (-3dB) cutoff AC couplingon all frequency ranges. User selectable10 Hz Hi-pass filter.

Frequency RangesFmax: 250 Hz, 1 KHz, 5 KHz, 20 KHz

Measurement SpecificationsSpectral Resolution 50, 100, 200, 400, or800 Lines. Peak locate function providesan effective resolution of 600,000 lines at100 Hz with no delay.

Averaging Spectrum Mode: Linear, Exponential orPeak Hold with selectable no. of averages.Balance Mode: Linear or Exponential.User selectable

Appendix 1 Specifications

A-1-1

IntegrationAnalog or digital integration fromacceleration to velocity, acceleration todisplacement or velocity to displacement.User selectable.2 Hz or 10 Hz high pass filter. UserSelectable

Measurement ModesBalance, Spectrum, Waveform, TachRatio, Blade Track & Lead Lag (OpticalTracker or Strobe), Overall (Scan)

Cursor FunctionsFrequency of Bin (Cursor on)Frequency of Signal (Peak Locate)Center for expand and compress

OutputVia host PC and MicroBase companionsoftware of History Report including polarplot, Spectrum Plot, Waveforms and anyscreen plot. Saved data can be uploaded tohost computer via Interface Cable PN1311 using MicroBase program runningunder Windows.

Data Storage Capacity512KB nonvolatile user storage (Limit of256 file entries). History file 11.5K; 400line spectrum 1.6K.Automatic Erasure ProtectionNonvolatile storage of calibration,programs and setup parameters.

Real Time ClockAll data automatically tagged withreal-time hour, minute, day, month, year. PC mounted independent Lithium powersource powers clock at all times. Clock Battery life expectancy >10 years.


A-1-2

Connector Pinouts


A-1-3

DFPS

E TACH GNDM +5VG -5VB ACC GND

AHJK

ACC 1ACC 2ACC 3ACC 4

18S Jack on MUX1450-1 or 1102.

1324

TACH ATACH BTACH CTACH D

+5VGND

Sig

ABCD

+5VGND

Sig

1097 Tach Cable

Instrument Sensor

B

A

GND

Sig

ABCD

GND

Sig

1096 Acc Cable

Instrument Sensor

RedGreen

White

Green

White

ABCDEFGHK

Sig BladeGroundSig Tip+5VSyncLED-5VTrigTach A

15S Tracker JackMS3112E14-15SMating PlugMS3116F14-15P

ABCD

+5VGround-5VSignal

4S Jacks on MUX (8)and 1131 Cable (2).MS3112E8-4SMating PlugMS3116F8-4P

Acc 1

Acc 2

MicroVib II

Mux 1450-1

Tracker

Typical Equipment Hookup Diagram

ABCDEFGHJKLMNPRSTU

Acc InputAnalog GroundFused BatteryTach InputDigital GroundDC Input-5VDC InputDC InputDC InputPeripheral Reset+5VNCSerial In TTLSerial Out TTLSerial Out RS232DC InputSerial In RS-232

18S Jack on MicroVib IIMS3112E14-18SMating PlugMS3116F14-18P

Photocell

Connector Pinouts

Cable Hookup Diagrams


A-1-4

Left Prop Acc

Right Prop Acc

MicroVib II

Mux Unit

Left PropPhotocell

Right Prop Photocell

Typical Twin Prop Diagram

Acc

MicroVib IIPhotocell

Typical Single Prop Diagram

1007 Cable

M/R Lateral Acc

M/R Vertical Acc

MicroVib II

Mux Unit

Tracker

M/R Photocell

Tail Rotor Acc

T/R Photocell

Typical Helicopter Diagram

Acc

MicroVib IIPhotocell

Typical Single Prop Diagram

1131 Cable 1096 Cable

1097 Cable

Charge Amplifier PN 1498

The DSS PN 1498 Charge Amp is designed to interface high temperature piezo-electricaccelerometers made by Dytran, PCB, Endevco, Vibro-Meter and B&K to the DSS MicroVibIITM Aircraft Vibration Analyzer. The unit features rugged construction, wide dynamic range,and excellent frequency response. A balanced differential input is designed for use with sensorsproviding an output impedance of 100K ohms or greater.

The 1498 is compatible with accelerometers producing levels ranging from 10 thru 200 pC/g.The output of the unit is an acceleration signal proportional to the charge sensitivity of thesensor. The output signal level (in mV) will be typically .4 times the charge sensitivity of theaccelerometer (in pC). This .4mV/pC cal factor will vary slightly from unit to unit. Its exactvalue is determined during factory calibration and is printed on a label permanently attached.This cal factor is not subject to significant drift over time since it is based on very stablecomponents. DSS recommends the cal factor be verified every two years.

EXAMPLE

The accelerometer has a sensitivity of 49.8 pC/g. The Charge Amp calfactor is .42mV/pC. The resulting signal level will be 49.8 X .42 = 20.92mV/g. This value should be entered into the MicroVib II with thefollowing key strokes:

On, Mode, Control Panel, Set Input Params, Setup CH 1 Sensor,Special Sensitivity, .02092, OK, Sensor Power (off), Done, Done,Done. This will put you in the Select Mode Screen.

NOTE

The charge amp does not use ICP Sensor Power, so it is best to turn itoff as above. (Unit will read correctly with sensor power on or off, butsensor power consumes battery power.)

The Charge Amp is connected to the accelerometer using DSS High Temp Cable PN 1084-10,1492 or 1507. The unit connects to the MicroVib II via an integral 15 foot cable that mates to theaccelerometer input of either a PN 1131 Breakout Cable, or a Signal Multiplex (MUX) Unit.

A-2-1

Multiplex Units

The Multiplex unit (MUX) connects to the MicroVib II and allows the user to connect numerousvibration sensors and tach sensors. The MicroVib II automatically selects the correct sensors foreach task as programmed by the group file. The user can also manually select sensors via theMicroVib II keypad. The MUX also provides a means of tracking helicopter blades via OpticalTracker or Strobe light. Some versions of the MUX can provide the sum or difference betweentwo vibration signals. Some versions can provide a single connector interface for up to 4vibration signals and 4 tach signals for pre-wired aircraft. MUX Version Matrix:

NoYesOptical46‘1700-1NoNoOptical46‘1700NoYesStrobe44‘1680-1NoNoStrobe44‘1680YesYesOptical44‘1560-1YesNoOptical44‘1560NoYesOptical44‘1450-1NoNoOptical44‘1450NoYesOptical416‘1440-1NoNoOptical416‘1440NoYesStrobe44‘1115 (OBS)NoYesOptical44‘1102 (OBS)A+B A-BMulti-InputTracker Tach ChVib. Ch.P/N

Vibration Sensors

The vibration inputs are compatible with ICP type sensors, self generating Velocity Sensors,Low impedance velocimeter type sensors. When DSS Accelerometers are used, no specialsettings are required. If other types of sensors are used, the parameters for the sensor must bekeyed in to the MicroVib II.

Tach Sensors.

The tach sensor interface is compatible with DSS PN 1015 Photo sensor, as well as commonlyused magnetic pickups, synchrophaser pulses, hall effect sensors and any other sensor that canproduce a 150mv or greater sine or pulse type waveform.

Optical Tracker Interface. (1440, 1450, 1700 MUX types)

A microprocessor in the MUX processes analog blade height data along with Tach and Bladepulse timing data to provide digital track information to the MicroVib II. The Optical TrackerPN 1145-5 connects to the MUX and is powered by the MicroVib II battery via the MUX cable.

A-3-1

Strobe Interface (1680 MUX only)

The microprocessor in the MUX unit measures the tach signal period and generates a pulse trainof equally time spaced pulses at any multiple of the tach pulse rate. This signal is opticallycoupled to the strobe jack to drive strobes commonly used for helicopter blade tracking. DSSdoes not make a strobe. The microprocessor can also slightly offset the time signals to stack orspread the blade tip target images. The number of blades and blade stacking functions arecontrolled from the MicroVib II keypad.

DC Power for Strobe (1680 MUX only)

A two pin MS receptacle is provided to route DC power to the strobe unit being used. DC Powercable DSS PN 1123 is available which has a commonly used 16-2P DC power plug which matesto several Bell Aircraft. DC power cable PN 1123A is also available which provides bare leads..

Multi-Input Connector Interface (All -1 versions)

An 18 socket MS Bayonet type Receptacle is provided to connect to aircraft that are pre-wiredfor multiple sensors. DeHavilland Dash 8, Beech 1900, Eurocopter AS365 and EC135 are a fewof the aircraft that can benefit from this feature.

A+B A-B Function (1560 MUX Only)

Several helicopter types use a balancing algorithm that requires a sum of two vibration signals aswell as the difference between two vibration signals. This signal math is performed usingprecision op amps before the signal is sent along to the MicroVib II.

Special Modified MUX Units.

DSS can modify MUX units as required for specific cases. MUX P/N 1450D is speciallymodified with a higher input impedance on the tach input, but also requires a much higher tachsignal amplitude. This was done to make it compatible with the Dornier 328 Aircraft.

Signal Simulator

The Signal Simulator PN 1117-2 provides an accurate vibration amplitude signal, accurate tachfrequency source with a known phase angle between the two signals. This device is often usedfor troubleshooting and a simple field cal check to be sure the MicroVib II is working properly.The vibration signal level will read between .765 and .845 IN/S, the phase will read between 270and 274 degrees, and the the tach speed will read between 1919.5 and 1920.5 RPM.

A-3-2

Customizing Group files

One of the most powerful features of the MicroVib II is its ability to precisely learn the responseof a particular aircraft. For fleet operators this capability can save hundreds of man-hours peryear. This power is only unleashed when group files for each individual aircraft are created andused. This app note sets out the steps needed to create these individualized group files.

Overview of the required steps

Step 1: Work the aircraft normally using the “standard” group file.

Step 2: View the data and identify new Tach Factors and Sensitivities.

Step 3: Edit the Group File with new values and re-name it.

Step 4: Print out and file the new group file.

Step 5: Upload the new Group File to the MicroVib II.

Step 6: Use the new group file the next time.

Details of Each Step

Step 1 Work the Aircraft Normally

Work the aircraft normally using the “standard” group file for that type of aircraft. This groupfile is available for download from the DSS website using MicroBase. Use the most up-to-dategroup file if possible.

Note: If you are using one of the built-in templates to work the aircraft, you will need to export thegroup file first in order to be able to edit it later. To export the group file, open the balancehistory and then press MODE, CONTROL PANEL, ADVANCED CONTROLS, SAVE (EXPORT)GROUP, enter a name for the group file and press OK.

Step 2: View the data and identify new Tach Factors and Sensitivities

Download the History files you just completed to MicroBase using the MicroBase DataManager. Annotate the files normally and add them to the database. Also download the groupfile that was used. Then select the history file and view the data.

Note: These steps are clearly illustrated in the MicroBase help section.

A-4-1

From this example data you can see that it took three moves to get from .694 IPS down to .051IPS. You can see that the original Sens and Tach factors were 12.0 and 320. You can see that thelast move was too short to learn from, as the Sens and Tach values didn’t change on the lastmove. So we have two pretty good moves to work with. If we average the values from the twomoves we get a Sens of 13.37 and a Tach of 309 degrees. Note these values down as we will usethem later. Step 3: Edit the Group File

While still in MicroBase, open the Data Manager again and look for the group file you wereusing on the aircraft in step 1.

A-4-2

First, Select the Group file you were using onthe aircraft

Then click on the Open Group button.

This screen should come up:

In this screen we can edit the group file. Click on the Next Task and Previous task keys to get tothe correct task. In this example it is Hov Lt. You can see the Sens and Tach are 12 and 320. Putthe cursor in the data box and key in the new values we determined earlier 13.5 and 309.

Do the same for the other tasks that you have good data for.

When the Group file is fully corrected, click on the “Save” button. This will save the changesand bring you back to the previous screen, the Data Manager. Select the newly edited group fileand click on the “Rename” button. Enter the tail number of the aircraft as the name for the newgroup file.

Step 4: Print Out and File the new Group File

In the Data Manager, select the newly re-named group file and click the “Open Group” button.The screen above will come up again. Click on the “Print Group” button and print out a papercopy of the new group file. File this copy as a means of controlling the data in these “custom”group files.

Step 5: Upload the new Group File to the MicroVib II.

Re-connect the MicroVib II to your computer and close and then re-open the data manager.Select the newly re-named group file in the left side of the screen and click on the right arrowbutton. This will upload the new group file to your MicroVib II.

A-4-3

Step 6: Use the new Group File next time

The next time you need to work that aircraft, be sure to select the special group file you havecreated with that aircraft tail number on it. Work the aircraft normally and then repeat step Twothru Five again. Every time you work the aircraft, you may find an improvement in the groupfile. Any time the first solution is not accurate, the tach factor and sensitivity need to becorrected*. Eventually the group file will match the aircraft precisely and the first moves will beextremely accurate. Of course every time a major aerodynamic component is changed, you canexpect the factors to shift some.

* The only exception to this “general rule” is when you have a non-linear responding system.Example: The Astar Short Shaft. In non-linear responding systems, the sens and tach factors shiftdepending on the vibration amplitude. In these cases, leave the sens and tach values alone unlessyou really understand the impact of your changes.

Keep in mind that the quality of the data in these “custom” group files is totally under yourcontrol. You must take this task very seriously to have good success. Making errors in thisprocess will increase man-hours rather than save them. If you cannot keep this data under tightcontrol, you are better off to just use the “standard” group files.

A-4-4

A+B A-B, A-3-2ADD WT key, 2-6ADVANCED CONTROLS, 1-5Advanced Options, 2-3Alarm Indicator, 2-1Alarm Level

Set, 2-3Angles

Measuring, 2-13Auto Shutoff, 1-10AUTO TRIGGER, 3-3AUTO-REPEAT, 3-3Average Type

Spectrum, 3-3Averaging, A-1-1

EXP (Smooth), 2-3Exponential, 1-8Linear, 2-3, 1-8Spectrum, 1-7

Averaging Data, 1-7Averaging Indicator, 2-1Azimuth Location, 6-4

Strobe, 7-3BACK TO PREV key, 2-5Background

Tracking, 6-4backlight

turning on, 1-4Balance

Mode, 2-1Options, 2-2

Balancing Procedures, 2-8Bandwidth, 2-1

Set, 2-3Bargraph

Signal Level, 2-1Battery

Care, 1-2Changing, 1-3Charging, 1-3Checking, 1-2Life, 1-3Self-Discharge, 1-2Status Indicator, 2-2

blade loading, 6-1Blade Tip distance, 6-2

Blade Tracking, 6-1brackets, 1-6Cables, 1-7Calibration, 1-10Channels

Sensor, 2-1Charge Amp, A-2-1Clear History, 2-10Cold Boot, 1-4Connector, A-1-1Controls / Load (Import) Group, A-5-1Create

Group File, 1-5History File, 1-5

CreatingGroup File, 2-11

Cursor ModeWaveform, 4-1

CURSR MODE keySpectrum, 3-2

Customer Support, 1-2Data Storage Capacity, A-1-2Date, 2-2

Set, 1-5Time, 1-5

DEC keySpectrum, 3-2

Default History Files, 2-9Delta Cursor

Waveform, 4-2Disk

Format, 1-6Display Units

Set, 2-3Spectrum, 3-3Waveform, 4-2

Double ImagesStrobe, 7-3

Dynamic Range, A-1-1Editing

Group Files, 2-13Effect of WindEnter Changes Screen, 2-5ENTER CHGS key, 2-5Entering Data, 1-9

Numeric, 1-10

Index

Index - 1

ErasingFiles, 1-8

EstimatingSensitivity Factor, 2-14tach offset, 2-3, 2-14

EvaluatingHistory, 2-10

EXP keySpectrum, 3-2

Exponential averagingSpectrum, 3-3

FileOpen, 1-8

File Name, 2-2Files

Erasing, 1-8Navigating, 1-8Recalling, 1-8Renaming, 1-8Saving, 1-8

flow chart, 2-15Format

Disk, 1-6Freeze Indicator, 2-2Frequency Range

Spectrum, 3-3Frequency Ranges, A-1-1Front Panel

Keys, 1-3Full Scale Range, 2-1function keys, 2-2

File, 2-2Help, 2-2Mode, 2-2Task, 2-2

Generic Balance, 2-8Group

Load, 1-6Save, 1-6

Group FileCreate, 1-5Creating, 2-11Printing, 2-12Saving, 2-12

Group files, 2-11Editing, 2-13

HannWindow, 2-3

Helicopter, 2-15High Pass Filter

Spectrum, 3-4History

Evaluating, 2-10View, 2-4

History File, 2-9Create, 1-5New, 2-10

HookupStrobe, 7-3

ICPsensor power, 1-5

Init DSP Unit, 1-6Initial Sensitivity

Set, 2-11Initial Tach Offset

Set, 2-11Input Channels

Set, 2-11Input Range, A-1-1Installation

Sensor, 1-6Installing

Photo sensor, 1-7Integration, A-1-2, 1-6interrupter, 1-6Keys

Front Panel, 1-3Last calibration date, 1-4LCD Contrast

Set, 1-4LCD Display, A-1-1Lead Lag, 6-2, 6-3Learn mode, 2-4LEVEL TRIGGER, 3-3Light Level, 6-3Linear averaging

Spectrum, 3-3Lithium battery, 1-5Live Data, 6-3Load

Group, 1-6Lockout Weight Computer, 2-5

Index

Index - 2

Magnetic Pickup, 1-6Many Weight Locations, 2-7Max Input Signal

Set, 1-6MAXIMUM INPUT, 3-3Measuring

Angles, 2-13Metric Units, 6-3MicroBase, 3-5, 2-13Micro-Disk, 1-4Minimum Frequency

Spectrum, 3-3minimum moveline, 2-3Mode

Balance, 2-1MODE Screen, 1-10Multi-Input Connector, A-3-2Multiplex unit, A-3-1MUX, 2-1Navigating

Files, 1-8New

History File, 2-10New radius key, 2-6Number of Averages

Spectrum, 3-3Number of Blades, 6-3

Strobe, 7-3Number of Lines

Spectrum, 3-3Number of Points

Waveform, 4-2Number of Revs

Set, 6-3Open

File, 1-8Optical

Tracking, 6-1Optical Tracker, A-3-1Options

Balance, 2-2Order

Set, 2-3Overall

Scan, 8-1Overlay Balance History, 2-3

Owner NameSet, 1-4

Peak HoldSpectrum, 3-3

Peak LocateSpectrum, 3-2

PhaseReadout, 2-1

Photo sensorInstalling, 1-7

pitch link, 2-15Plotted data point, 2-2Points

Waveform, 4-1Polar Plot, 2-1Power On Self Test, 1-3predicted vibration, 2-5Printing

Data, 1-9Group File, 2-12

Printing History, 2-9Procedure

Strobe Tracking, 7-3Tracking, 6-6

ProceduresSpectrum, 3-5Weighing, 2-9

program rotor, 2-11Propeller-Rotor

Protractor, 2-13Protractor

Propeller-Rotor, 2-13READY FOR TRIGGER, 6-1READY TO FIRE STROBE, 7-2Real Time Clock, A-1-2Recalling

Files, 1-8Renaming

Files, 1-8Restore Factory Defaults, 1-6Restore Task Defaults, 2-11Rmove Prev Chngs key, 2-5RPM

Readout, 2-1Run number, 2-4Sample Rate

Index

Index - 3

Waveform, 4-1, 4-2Save

Group, 1-6Save Plot

Spectrum, 3-2Saving

Files, 1-8Group File, 2-12Screen, 1-8

ScanTrue RMS, 8-2

Scan Modes, 8-1Screen

Saving, 1-8Screen Title, 2-2Select

Task, 2-10Sens Factor

Defined, 2-2Set, 2-2

Sensitivity FactorEstimating, 2-14

sensorCables, 1-7Channels, 2-1Installation, 1-6, 1-7Power, 1-5Sensitivity, 1-5Type, 1-5

sensor power, A-1-1ICP, 1-5

Serial Number, 1-4Set

Alarm Level, 2-3Bandwidth, 2-3Date, 1-5Display Units, 2-3Initial Sensitivity, 2-11Initial Tach Offset, 2-11Input Channels, 2-11LCD Contrast, 1-4Max Input Signal, 1-6Number of Revs, 6-3Order, 2-3Owner Name, 1-4Sens Factor, 2-2

Tach Offset, 2-3Target Level, 2-3Task Name, 2-11Time, 1-5Track Distance, 6-3

Set Trigger, 3-3SET TRIGGER DELAY, 3-3SET TRIGGER LEVEL, 3-3Setup

Task, 2-11Show Overall, 3-4Signal Simulator, A-5-1, , 1-10Single Shot, 3-3

Spectrum, 3-3Waveform, 4-2

Skip Factor, 2-12Solution Screen, 2-4Special Characters, 1-9Specifications, A-1-1Spectrum

Average Type, 3-3Averaging, 1-7CURSR MODE key, 3-2DEC key, 3-2Display Units, 3-3EXP key, 3-2Exponential averaging, 3-3Frequency Range, 3-3High Pass Filter, 3-4Linear averaging, 3-3Minimum Frequency, 3-3Number of Averages, 3-3Number of Lines, 3-3Peak Hold, 3-3Peak Locate, 3-2Procedures, 3-5Save Plot, 3-2Single Shot, 3-3Window Type, 3-5

Spectrum Mode, 3-1Spectrum Options, 3-3Split weight mode, 2-6SPLIT WT key, 2-4, 2-6Spreading Weights, 2-7Standard Equipment, 1-1standard rotor, 2-11

Index

Index - 4

Start (TRG), 6-3START ANLS key, 2-5Status Indicator, 2-2Strobe

Azimuth Location, 7-3Double Images, 7-3Hookup, 7-3Number of Blades, 7-3Tach Signal, 7-3Tracking, 7-1

Strobe Interface, A-3-2Strobe Tracking, 7-2

Procedure, 7-3Strobe Tracking Options, 7-3system parameters, 1-4System RAM, 1-4tab adjustments, 2-15Tach Generator, 5-1Tach Offset

Defined, 2-3Estimating, 2-3, 2-14Set, 2-3

Tach Ratio, 5-1Tach Sensors, A-3-1Tach Signal, 6-3

Strobe, 7-3TACH TRIGGER, 3-3Tare, 2-9Target Level

Set, 2-3Task

Name, 2-1Select, 2-10Setup, 2-11

Task Functions, 2-10Task Name, 2-4

Set, 2-11Template

name, 2-2Templates, 2-12Temporary locations, 2-6Time, 2-2

Date, 1-5Set, 1-5

Time AxisWaveform, 4-1

Time unitsWaveform, 4-1

Track DistanceSet, 6-3

Tracker Configurations, 6-7TRACKER DISABLED, 6-2Tracking

Background, 6-4Optical, 6-1Procedure, 6-6Strobe, 7-1

trigger, 3-3True Peak Hold, 8-1True RMS

Scan, 8-2Undo key, 2-5Un-splitting Weights, 2-6Verify Screen, 2-5Very Light Weights

Weighing, 2-9Vibration Sensors, A-3-1View History, 2-9Waveform

Cursor Mode, 4-1Delta Cursor, 4-2Display Units, 4-2Number of Points, 4-2Points, 4-1Sample Rate, 4-1, 4-2Single Shot, 4-2Time Axis, 4-1Time units, 4-1

Waveform Mode, 4-1Weighing

Procedures, 2-9Very Light Weights, 2-9

Weight Computer, 2-6Weight Computer Lockout, 2-5Weights Too Big, 2-7Wind, Effect ofWindow

Hann, 2-3Window Type

Spectrum, 3-5

Index

Index - 5

Troubleshooting

Use Signal Simulator toverify signal levels.

Input settings incorrect orunit out of calibration.

Vibration amplitude seemswrong.

Return to DSS for repair.MicroDisk (U5) defectiveStorage Error during POST

Return to DSS for repair.Normal if temp below 32F(0C) otherwise, badconnection in charger circuit.

Charge light won’t come on.

Return to DSS for CPUsocket update. Note 3

CPU socket connections notgood.

Unit acts flakey orintermittant.

Check battery & charge orreplace. Note 2

Dead battery.Unit won’t turn on

Inspect keypad ribbon andre-install or replace keypad.

Keypad ribbon worn or looseUnit won’t turn on.

Do a Cold boot. Note 1.LCD contrast set too low ortoo high.

Screen blank or black, butunit beeps normally.

Reload group file (Mode /Control Panel / AdvancedControls / Load (Import)Group or Cold boot.

Group file data in history filecorrupt.

Strange characters in tasknames

Restore defaults includinginput defaults or do a Coldboot. Note 1.

Input units data corruptedNo vibration data, strangecharacters for vibration units

RemedyLikely CauseProblem/Symptom

Note 1: To perform a Cold boot: (1) Turn unit off. (2) Press and hold down the ON/OFF key for10 seconds and release. Unit will start in a normal fashion, but all settings will be default settingsand a new default balance history will be created. These settings are being read from theEPROM chip, which cannot be changed and are therefore virtually guaranteed to be free of anycorruption.

Note 2: To get battery replaced, return to factory..

Note 3: This only applies to serial numbers 1004 thru 1051, and most of these early units havealready been updated. Units after serial 1051 have the CPU chip soldered in.

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Warranty

Dynamic Solutions Systems, Inc. (DSS) warrants its MicroVib II and Accessories to be freefrom defects in material and workmanship for a period of twenty four (24) months from the dateof receipt by its original purchaser. This warranty covers hardware, firmware and softwareproducts. This warranty is not transferable.

This warranty is limited to repair or replacement, at DSS option, of any component or assemblywhich in the opinion of DSS is defective. This warranty does not apply to items subjected tomisuse or abuse. This warranty applies only to DSS products and does not apply to consequentialdamages that may result from any use or misuse of the product(s).

Customers desiring warranty service shall obtain a return authorization number from DSS or oneof its authorized representatives. This return authorization number shall be referenced on theoutside of the package used to return the product for service. Upon receipt and inspection of thereturned product, DSS will promptly inform the shipper of an anticipated return date. If warrantyservice is required, the repaired unit will be returned prepaid to the originator.

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Revision History

4-2-07 Rev B: Removed battery replacement instructions & added note indicating DSS will testbattery during routine calibration.

4-24-07 Rev C. Add mention of Weight Computer Lockout after run2 when REM PREVWeights key is active. Page 2-5.

7-6-07 Rev D. Add note after Direct Printing procedure explaining how to printout completebalance history. Pg 1-9.

4-27-08 Rev E. Remove all references to direct printing, 1352 Cable and 1224 Adapter.

7-3-10 Rev F. Add info about tracking setup & use including illustration. Update CustomizingGroup files using MicroBase Pro screens.

5-17-11 Rev G: Add info about Signal Simulator and MUX units.

9-18-12 Rev H: Add info about firmware V1.34 & 1.35.

7-19-13 Rev I: PN 1312 (UK) Case replaced by PN 1990 Case. (Pelican)

2-10-14 Rev J Add section 5.2 Warranty.

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Documents

MicroVib II Aircraft Analyzer