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 behind the pilot seat with the connectors facing up and secure DAU using canvas straps and D-rings.
d. Remove hood assembly from one of the pilot's console lights. Remove the bulb. Plug AH-1S power cable
adapter (29317100), figure 2 into lamp socket. Ensure that the lamp intensity is set to full intensity (clockwise).
e. Connect the grounding clip to a screw head or any non-painted metal surface, which will provide an adequate
path to aircraft ground.
f. Connect power cable (29317100) to DAU receptacle marked 28 Vdc.
g. Connect CADU to DAU cable (29325601) to CADU and to DAU receptacle marked CADU.
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) anywhere on the airframe that an irregular or unusual vibration is
b. Connect accelerometer cable (29105605) from accelerometer to the DAU receptacle marked ACC1, ACC2,
ACC3, 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
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, then press DO.
f. Use cursor keys to highlight aircraft type based on table 2, 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 characters), 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. Verify that the desired Test State (ACC1, ACC2, ACC3 or ACC4) is
I. Press DO when the aircraft is stable at desired condition. Re-verify that the aircraft is at the desired condition
(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
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.
By comparing the spectrums gathered, the source of an
unusual vibration may be located.
o. Make corrections and repeat task 6.
p. Make appropriate logbook entry and remove test equipment. END OF WORK PACKAGE