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Rotor Track and Balance

Rotor Track and Balance. Product Support ACES Systems/TEC Aviation Division support@acessystems.com. 06/06/2011 # 1. Overview. Rotor Balance Types of Balance Equipment Installation Data Acquisition and Making Adjustments Troubleshooting. 06/06/2011 # 2. Rotor Balance.

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Rotor Track and Balance

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  1. Rotor Track and Balance Product Support ACES Systems/TEC Aviation Divisionsupport@acessystems.com 06/06/2011 #1

  2. Overview • Rotor Balance • Types of Balance • Equipment • Installation • Data Acquisition and Making Adjustments • Troubleshooting 06/06/2011 #2

  3. Rotor Balance • What is an imbalance? • Advantages and disadvantages • Causes of imbalance • Other sources of vibration 06/06/2011 #3

  4. Rotor BalanceWhat is an imbalance? • A condition where there is more weight distributed on one side of a rotating component than on the other side 06/06/2011 #4

  5. Rotor BalanceAdvantages • Simple • Cost efficient • Cost effective 06/06/2011 #5

  6. Rotor BalanceDisadvantages • Noise • Vibration 06/06/2011 #6

  7. Rotor BalanceCauses of Imbalance • Manufacturing tolerances • Shimming and alignment • Rotor track • Static track • Dynamic track 06/06/2011 #7

  8. Rotor BalanceRotor Track • Static track • Perfect track if all blades produce the same lift • Assumes that blade twist, profile, and stiffness are equal on all blades • Assumed then to give equal lift on all surfaces of the blade 06/06/2011 #8

  9. Rotor BalanceRotor Track • Dynamic track • How the rotors fly during operation • More important to sacrifice a perfect tip path track for a rotor that is perfectly balanced 06/06/2011 #9

  10. Rotor BalanceOther Sources of Vibration • Mechanical looseness • Misalignment • Track • Worn bearings 06/06/2011 #10

  11. Types of Balance • Dynamic track and balance • Purpose of balancing • Types of imbalance 06/06/2011 #11

  12. Types of BalanceDynamic Track and Balance • First introduced in the late 1950’s • Operators found that virtually all statically balanced rotors were out of balance dynamically when installed. 06/06/2011 #12

  13. Types of BalancePurpose of Balancing • Static • Knife edge • Suspended arbor • Bubble balance 06/06/2011 #13

  14. Types of BalancePurpose of Balancing • Dynamic • Performed during operation • All of the rotating components are balanced as an assembly 06/06/2011 #14

  15. Types of BalanceTypes of Imbalance • Mass imbalance • Distribution of the mass • Spanwise or chordwise • Aerodynamic imbalance • Out-of-track condition exists 06/06/2011 #15

  16. Types of BalanceBenefits to Dynamic Balance • Enhance comfort • Reduce wear • Increase safety by reducing component stress • Lower operating costs 06/06/2011 #16

  17. Equipment • Sensors • Tach sources • Vibration measurements • Amplitude and phase 06/06/2011 #17

  18. EquipmentSensors • Accelerometers • Displacement sensors • Velocity sensors 06/06/2011 #18

  19. EquipmentAccelerometers • Measure acceleration • Typically reported in g’s • More sensitive to higher frequencies • Directly related to force caused by unbalance • Used in balancing (after conversion to velocity or displacement) 06/06/2011 #19

  20. EquipmentDisplacement Sensors • Measure change in position • Typically reported in mils (.001 of an inch) peak to peak • More sensitive to Low frequencies • Directly related to movements due to imbalance • Seldom used in balance (however, displacement units are often used) 06/06/2011 #20

  21. EquipmentVelocity Sensors • Measure velocity • Typically reported in IPS peak • More sensitive to medium frequencies • Directly related to energy from imbalance • Often used in balance 06/06/2011 #21

  22. OUTPUT CONNECTOR AND AMPLIFIER PRELOAD SCREW SEISMIC MASS PIEZOELECTRIC ELEMENT IN COMPRESSION PEDESTAL BASE EquipmentSensor Construction 06/06/2011 #22

  23. EquipmentTach Sources • Magnetic pickup • Phototach 06/06/2011 #23

  24. EquipmentMagnetic Pickup 06/06/2011 #24

  25. EquipmentPhototach 06/06/2011 #25

  26. EquipmentVibration Measurements • Amplitude and phase • Correlation between the trigger of the tach source and the time until the sensor registers the maximum amplitude. • The result will be a phase angle in degrees or time (clock angle) 06/06/2011 #26

  27. Installation • Sensor • Tach Source • Tip Targets 06/06/2011 #27

  28. InstallationSensor 06/06/2011 #28

  29. InstallationTach Source 06/06/2011 #29

  30. InstallationTip Targets 06/06/2011 #30

  31. InstallationOptical Tracker • Optical devices obsolete tip targets 06/06/2011 #31

  32. Data Acquisition and MakingAdjustments • Polar plotting • Automated solutions • Rotor track and balance • Rules 06/06/2011 #32

  33. Data Acquisition and Making AdjustmentsPolar Plotting • IPS and phase values are taken from the analyzer and manually plotted on charts to obtain a correction. 06/06/2011 #33

  34. Data Acquisition and Making AdjustmentsAutomated Solutions • The analyzer is used to collect the phase and IPS readings then calculates a solution • The calculated solution is then implemented by the user eliminating manual calculations 06/06/2011 #34

  35. Data Acquisition and Making AdjustmentsRotor Track and Balance • Pitch links • Tab • Sweep • Tip weight • Hub weight • Blade chordwise weight 06/06/2011 #35

  36. Data Acquisition and Making AdjustmentsPitch Links • Changes the lift of the blade by adjusting the angle of attack at the rotor hub • Characteristically changes the tip path plane throughout speed range • Characteristically has large drag changes resulting in a strong effect on lateral balance 06/06/2011 #36

  37. Data Acquisition and Making AdjustmentsPitch Links Eurocopter SA330 Puma AgustaWestland AW139 06/06/2011 #37

  38. Data Acquisition and Making AdjustmentsTab • Changes the lift of the blade by adjusting the twist in the blade aerodynamically • Characteristically changes the tip path plane at higher airspeeds • Characteristically has small drag changes resulting in little affect on the lateral vibrations 06/06/2011 #38

  39. Data Acquisition and Making AdjustmentsTab Eurocopter EC135 AgustaWestland AW139 06/06/2011 #39

  40. Data Acquisition and Making AdjustmentsSweep • Changes the balance of the rotor head by adjusting the center of mass • Characteristically changes the mass at all air speeds • Characteristically it has little effect on the lift of the rotor and the vertical vibration 06/06/2011 #40

  41. Data Acquisition and Making AdjustmentsSweep Bell 206 Series Sweep Adjustment 06/06/2011 #41

  42. Data Acquisition and Making AdjustmentsTip Weight • Changes the mass of the rotor head by adjusting blade weight • Characteristically no change to tip path plane • Characteristically has a large effect on lateral vibration 06/06/2011 #42

  43. Data Acquisition and Making AdjustmentsTip Weight M/R MI 8/17/24 Tip Weight Adjustment T/R 06/06/2011 #43

  44. Data Acquisition and Making AdjustmentsHub Weight • Changes the mass of the rotor by changing rotor head mass • Characteristically has large effects on the lateral vibration • Characteristically has no effect on tip path plane 06/06/2011 #44

  45. Data Acquisition and Making AdjustmentsTip Weight BO 105 M/R Hub Weight - Hollow Bolt EC155 M/R Hub Weight - Washer 06/06/2011 #45

  46. Data Acquisition and Making AdjustmentsHub Weight Bell 407 T/R Irregular Bell 206 Series T/R Regular 06/06/2011 #46

  47. Data Acquisition and Making AdjustmentsBlade Chord Weight • Changes the center of gravity of the blade • Characteristically changes tip path with changes in collective force • Characteristically has large effects on verticals • Characteristically has large effects on laterals at ground/hover and in letdowns 06/06/2011 #47

  48. Data Acquisition and Making AdjustmentsBlade Chord Weight Bell 407 Chord/Product Weight 06/06/2011 #48

  49. Troubleshooting • Polar Plotting - Human error • Worn components • Structural resonance 06/06/2011 #49

  50. TroubleshootingPolar Plotting • Human Error • The result of an adjustment increases the IPS or the moveline 180 degrees out 06/06/2011 #50

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