100HR (Task 8)

AVA APPLICATION AND PROCEDURES EH/UH-60 CONT.

Table 1. EH/UH-60 Flight Plans and Test States

TM-1-6625-724-13P Aviation Vibration Analyzer Manual
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TM 1-6625-724-13&P 0069 00 0069 00-3 The UH-60 Flight Plans are listed below with a brief description of their purposes. The selectable Flight Plans (see table 1) are listed in order of appearance in the menu on the CADU and not in the order in which they are to be performed. 100HR (Task 8) The UH-60 100 hour vibration survey is performed on the engines and oil cooler (see task 8). This procedure measures the vibration levels of the components only, and does not offer corrective actions for out-of-tolerance conditions. ABTUNE (Task 7) This is a test designed for measurement and diagnosis of the UH-60 4/REV-cantilever spring cabin absorber. It consists of a sweep through a series of Nr points to measure the effectiveness of the cantilever spring cabin absorber at different rotor RPM. It should be performed when directed by the CADU or when the cabin 4p becomes excessive. The AVA evaluates the 4/REV cabin levels during each FLIGHT plan. The operator may be directed to perform ABTUNE while running main rotor diagnostics. BOXABS (Task 7) This is a test designed for measurement and diagnosis of the UH-60 4/REV cabin box absorber. It consists of a sweep through a series of Nr points to measure the effectiveness of the cabin box absorber at different rotor RPM. It should be performed when directed by the CADU or when the cabin 4/REV becomes excessive. The AVA evaluates the 4/REV cabin levels during each FLIGHT plan. The operator may be directed to perform ABTUNE while running main rotor diagnostics. If box absorbers are installed run the BOXABS flight plan. ENG_1, ENG_2 (Task 9) This is a separate test designed for the L-model (and for the A-model with a balance kit installed) EH/UH-60 aircraft (see task 8). It will offer corrective actions in the form of balance washers installed on the forward end of the engine output shaft. FLIGHT (Task 4) This test is primarily designed to reduce the in-flight main rotor 1/REV vertical (A+B) and roll (A-B) to specified levels, using Pitch Change Links (PCL) and tabs only. By default hub weights are turned off. This test is designed to be performed only after the main rotor track at flat pitch 100% Nr is less than 0.5 inches and the main rotor is balanced on the ground (A-B at flat pitch 100% Nr<0.2 ips). It is not recommended to proceed to FLIGHT until these conditions are met, doing so may cause unnecessary flight time. If no recent maintenance has been performed on the rotor but the vibration levels are unacceptable, this flight plan can be used to reduce the vibration levels to within the recommended limits without performing GNDTRK and/or GNDBAL. GNDBAL (Task 3 & 5) This is the final ground run to be performed prior to and at the completion of the FLIGHT rotor smoothing. It makes a weight adjustment on the rotor to reduce the flat pitch main rotor 1/REV A-B. This flight plan is to be used after the final rotor smoothing flight if the in-flight PCL and/or tab adjustments have put the ground balance above the limit. GNDTRK (Task 2) This flight plan flat tracks the main rotor prior to balancing. It is recommended that this flight plan be used after any blade or PCL replacement and prior to any other major main rotor work. It will adjust pitch links to optimize track, without regard to balance changes. If the aircraft is already in service and the operator simply wishes to improve the vibration levels, do not perform the GNDTRK task. PROBES (Task 10) This flight plan is designed to acquire data from up to four accelerometers to assist in isolating irregular or unusual vibrations. This flight plan will measure data one channel at a time on DAU ACC1 through ACC4. Accelerometers may be installed anywhere on the airframe and will measure a 0 to 500 Hz spectrum (0 to 30,000 RPM). TAIL (Task 6) This flight plan is designed to balance the EH/UH-60 tail rotor. It uses the optical RPM sensor on tach channel 2 and one accelerometer on ACC4. It should be performed after any rework on the tail rotor or any time a medium to high frequency vibration is felt in the aircraft.

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