1. Rotor Track and Balance Only????

2. Agenda History of Rotor Track and Balance. Vibration Requirements Increasing. Using the Tools You Have. Cost Savings.

3. History of Rotor Track and Balance Flat Track and GO!

4. History of Rotor Track and Balance (Cont.) And the Maintenance Manual Said “Try the Pitch Link. If that does work Try the Tab!”

5. History of Rotor Track and Balance (Cont.) And Jim Chadwick Said “There has got to be a better way” And an Industry was Born

6. History of Rotor Track and Balance (Cont.) Computer Based Track and Balance

7. Computer Based RT&B SUGGESTIONS –Always do all changes requested or enter in changes performed. –No track and balance equipment will ever help if the adjustments are not performed correctly. Verify that the adjustment is performed on the correct blade –Verify Equipment Installation Computers are Stupid - They only know “OFF” or “ON”

8. Vibration Requirements Increasing WHY? –Safety –Cost Savings –Because the tools currently have the capability. Manufacturers Increasing Requirements Increased Flight Regimes (S-76 125Kias,145KIAS,155KIAS)(Bell 407) Increase in complexity More Limits, More Regimes, More ….. Scheduled Vibration Level Checks

9. More Vibration Requirements Other requirements AS-350/355 Driveshaft hourly requirement BELL 407 Flywheel, FRAM Dampener Turbomeca 400 Hour Vibration Check Manufacturers put out limited freq chart as Aid to troubleshooting

10. Tail Rotor Ground Balanced

11. Tail Rotor Vertical and Lateral Ground Balanced

12. Tail Rotor Vertical and Lateral Ground & Flight Balanced

13. Safety US Marine Corp H-46 Rotor Head Bearing Failure Squadron Pilots had complained about an unusual vibration. Aircraft was put in a functional test flight mode and vibration analysis performed. The below spectrums show that both the forward and aft rotors tripped the 1 per alarms indicating a balance problem. The trend shows a significant increase in 1 per vibrations with several trend points. The crew decided not to perform any maintenance actions and assumed that it was “JUST” that the aircraft needed balanced and it could wait until scheduled maintenance. 7.5 flight hours later one of the forward head Horizontal Hinge pin bearings failed which resulted in a violent 1 per that forced an immediate shut down. Further inspections revealed a crack in the forward transmission mounting structure which we have yet determine if this is collateral damage or preexisting damage. Components are on their way to Cherry Point for analysis. NOTE: The Maintenance Manual requires an inspection and RT&B exercise anytime the rotors trip the 1 per alarms.

14. Fwd Rotor Lateral Spectrum H-46 Data Prior to Failure Fwd Rotor Lateral Trend

15. Horizontal Hinge Pin Bearing Failure Fwd Transmission Mounting Structure Crack

16. H-53E Swashplate

17. H-53E - Good Bearing

18. H-53E - Bad Bearing

19. Bearing Harmonics

20. Using the Tools You Have Using Spectrum to Detect –Detecting Imbalance –Misalignment –Mechanical Looseness –Resonance

21. Imbalance Signs of Unbalance –Vibration Occurs at 1 per Rev. –Amplitude Increases with Speed. –Phase or Clock angle is stable.

22. Aircraft Data - Ground Ground 4.3 IPS’s

23. Aircraft Data After HSS Change All regimes well below limits

24. Questionable Adapter Balance Excessive Grinding Excessive Grinding

25. Misalignment Characteristics of Misalignment –High Levels at 2X Shaft Speed (Elliptical Orbit) –Fore/Aft Readings are High –Fore/Aft Measurements are 180 Deg out of Phase –No Raised Noise Floor

26. MH-53J Engine Driveshaft Detected After Routine Maintenance Plot is of Average Vibration Level of Each Flight for the Driveshaft Shaft Bearing changed during phase inspection Bearing reinstalled correctly

27. SH-60B IGB Misaligned Gears

28. Mechanical Looseness Loose Bolts, Structural Frame Cracks, Wear Between Bearing and Supports Raised Noise Floor Phase or Clock Angle is Unstable

29. S-61N TRDS Structural Crack Per Flight Averages of Tail Rotor Drive Shaft 1P

30. S-61N TRDS Structural Crack Dramatic Increase in 1/P and 2/P levels as RPM Decreases

31. S-61N TRDS Structural Crack 1P 2P 3P

32. Resonance

33. Resonance / Natural Frequency Frequency that an object will vibrate when excited. Frequency will not vary with RPM. Fn = 2*PI*f k/m –Where k = Stiffness and m = mass Guitar Strings, Tuning Forks, Aircraft ground Resonance, Absorbers, Hammers, etc ….

34. Aircraft Data - H46 High Speed Shaft Extremely High Vibe at Resonance frequency Note 1 per is in limits G-meter would have missed this resonance

35. Aircraft Data After HSS and Adapter Change No resonance

36. Damaged Sensors Due to HSS Resonance

37. H-46 Mixbox Gear Resonance (Waterfall)

38. Cost Savings Cost Savings Through : Vibration Reduction Continuous Monitoring Reduced Maintenance Time by Aircraft Hardwiring

39. Vibration Reduction P3: US Navy,1 Year Prop Vibration Reduction Results of Initial Squadron Trial MeasureEffect of Vibration Reduction to 0.15 IPS Total Failures Before/’After Prop BalanceDecreased by 22.8 Percent Maintenance Man Hours Per Flight HourDecreased by 11.5 Percent Total Maintenance Man Hours “O” LevelDecreased by 19 Percent Total Maintenance Man Hours “I” LevelDecreased by 16 Percent Flight Hours Per Maintenance ActionIncreased by 4 Percent

40. Continuous Monitoring US Air Force Record of Cost Reduction and High ROI Fleet size = 47 AFSOC MH-53J Aborts per month pre VMS 23.5 per month post VMS 14.1 Aborts per month saved 9.4 Aborts per fleet prevented per year 12 months x 9.4 aborts = 112.8 aborts/year 2 flight hours lost/abort 112.8 x 2 hours x $3,500/hour = $789,600 saved per year VMS - Vibration Monitoring System

41. Aircraft Hardwire Savings Manufacturers Requirements Are Increasing. –Some Aircraft are coming from Factory Hardwired for Routine tasks (S-76, EC-135) Savings From; –Reduced Installation / Removal time –Equipment Life increases (most damage comes from removal and installation) –More Frequent analysis performed –Overall Safety improvements

42. Conclusions Rotor Track and Balance has Changed Vibration Requirements are increasing Significant Cost Savings are available