Figure 18. UH-60 Box Frame Absorber Main Rotor 4/REV Vibration Check And Tuning Procedure

PROCEDURE 5: IN-FLIGHT CHECK OF ABSORBERS (Box Type)

Table 2. UH-60 Box Frame Absorber Tuning Weight Adjustments

TM-1-6625-724-13P Aviation Vibration Analyzer Manual
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TM 1-6625-724-13&P 0069 00 0069 00-31 Install vibration equipment (task 1) (pilot, copilot and pilot heel vertical accelerometers) Perform FLIGHT Measurement (task 4) to obtain Pilot Heel Vertical at 120 knots, 100%Nr Pilot Heel Vertical at 140 knots, 100%Nr Cockpit A+B at 140 knots, 100%Nr Perform BOXABS Measurement: 140 knots Cabin Absorber Frame Vertical at 98, 99, 100, 100.5, 101, and 102%Nr Install vibration equipment for task 7 (Cabin Absorber Frame Vertical accelerometer) Add Tuning Weight to Nose Absorber based on maximum PHV ips level (See table 2.2) Remove Tuning Weight from Nose Absorber based on Minimum PHV ips level (See table 2.3). Adjust Cabin Absorber Tuning Weight based on minimum Cabin Absorber frame ips level (See table 2.1). (REFLY) (REFLY) Is Main Rotor 4/REV Cockpit Vibration within the following limits? Cockpit A+B 0.40 ips or less at 140 knots, 100%Nr Pilot Heel Vertical 0.60 ips or less at 120 knots and 140 knots, 100%Nr Main Rotor 4/REV Vibration is Acceptable Is Cockpit Vertical at 140 knots 0.40 ips or less? Is Pilot Heel Vertical 0.60 ips or less at 120 knots and 140 knots, 100 %Nr? Is Pilot Heel Vertical 0.30 ips or less at 120 knots and 140 knots, 100 %Nr? Is 140 knots Cabin Absorber Frame Vertical minimized at 100.5%Nr? YES NO YES NO YES NO YES NO YES NO Install vibration equipment task 1 (pilot, copilot and pilot heel accelerometers) Perform FLIGHT Measurement (task 4) Pilot Heel Vertical at 120 knots, 100%Nr Pilot Heel Vertical at 140 knots, 100%Nr Cockpit A+B at 140 knots, 100%Nr (REFLY) Figure 18. UH-60 Box Frame Absorber Main Rotor 4/REV Vibration Check And Tuning Procedure

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