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TM 1-6625-724-13&P
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TASK 6 - ISOLATING IRREGULAR/UNUSUAL VIBRATIONS
PROCEDURE 1: EQUIPMENT INSTALLATION
a. Remove AVA equipment from transport case. Check for possible damaged equipment and frayed cables.
b. Install DAU in canvas carrying case.
c. Place DAU in a back seat with the connectors facing up and secure using aircraft shoulder and lap belts and
canvas straps.
d. Connect the DC power cable (29104700) to the aircraft power receptacle in the overhead panel and to the DAU
receptacle marked 28 Vdc.
e. Locate CADU in aircraft. Connect CADU to DAU cable (29325601) to CADU and to DAU receptacle marked
CADU.
PROCEDURE 2: ACCELEROMETER INSTALLATION
NOTE
Data can be acquired from up to four accelerometers to
assist in isolating Irregular or unusual vibrations.
Operator must denote orientation and location of each
accelerometer.
a. Mount/install accelerometer (28110900) (found in the basic kit) anywhere on the airframe that an irregular or
unusual vibration is detected.
b. Connect accelerometer cable (29105800) (found in the basic kit) from accelerometer to the DAU receptacle
marked ACC1, ACC2, ACC3, and/or ACC4. The flight plan will measure data on one channel at a time.
PROCEDURE 3: PERFORM PROBES MEASUREMENTS
a. Operate aircraft at desired flight condition. This should be the RPM or airspeed at which the vibration is
strongest.
b. Turn on DAU.
c. Turn on CADU.
d. Press QUIT on the CADU until all selections are undefined.
e. Use cursor keys to highlight Aircraft Type, and then press DO.
f.
Use cursor keys to highlight OH-58A/C, and then press DO.
g. Tail Number is highlighted. Press DO.
h. Use cursor keys to highlight a tail number or enter a new tail number (up to seven digits), then press DO.
i.
Flight Plan is highlighted. Press DO.
j.
Use cursor keys to highlight PROBES. Press DO.
k. Enter the MEASURE mode by pressing F1. Verity that Test State ACC1 is highlighted.
l.
Press DO when the aircraft is stable at the highlighted selection. Re-verify that the aircraft is at the required
Test State (ACC1, ACC2, ACC3, or ACC4) and press DO again. The flight plan will measure data on one
channel at a time. Perform this operation each time a measurement is completed and another Test State to be
measured is highlighted. The AVA will acquire vibration data at each selected Test State and then return to
the selection menu.
m. After the last measurement is completed, press DO on Finish, then press DO on Main Menu.
n. Enter the Display mode by pressing F2. Select One Test State and press DO. Review each of the spectrums
measured for any unusual vibrations.
o. Make corrections and repeat task 6.
p. Make appropriate logbook entry and remove test equipment.
END OF WORK PACKAGE
