TASK 6 - ISOLATING IRREGULAR/UNUSUAL VIBRATIONS
PROCEDURE 1: EQUIPMENT INSTALLATION
a. Remove AVA balancing equipment from transport case. Check for possible damaged equipment and frayed
b. Install DAU in canvas carrying case.
c. Secure DAU in Avionics compartment strapped on top of the ASN-137 Doppler Signal Data Converter with the
connectors facing forward and secure DAU using straps.
d. Connect the DC power cable (29104700) to the aircraft power receptacle located to the right side of the CPO's
cyclic and to the DAU receptacle marked 28 Vdc.
e. Place CADU in front seat. Connect CADU to DAU cable (29325601) to CADU and to DAU receptacle marked
PROCEDURE 2: ACCELEROMETER INSTALLATION
Data can be acquired from up to four accelerometers to
assist in isolating irregular or unusual vibrations.
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 (29105600) (found in the basic kit) from accelerometer to the DAU receptacle
marked ACC1, ACC2, ACC3 or ACC4.
PROCEDURE 3: PERFORM PROBES MEASUREMENTS
a. Operate aircraft at desired flight condition. This should be the RPM or airspeed at which the vibration is
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.
Select aircraft type OH-58D. 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.
Flight Plan is highlighted. Press DO.
Use cursor keys to highlight PROBES. Press DO.
k. Enter the Measure mode by pressing F1. Verify that Test State ACC1 is highlighted.
Press DO when the aircraft is stable at the highlighted selection. The first time the DO key is pressed, the
system performs a self-test of all installed equipment and readies the DAU to acquire data for that Test State
(the CADU will prompt the operator with an asterisk and test condition when all equipment is ready). 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. Replace or repair component causing vibration problem.
p. Repeat procedure 3 again to determine if vibration is in fact reduced to acceptable levels.
q. Once acceptable vibration levels have been obtained, remove all test equipment from aircraft and make
appropriate log entries.
END OF WORK PACKAGE