TM 1-6625-724-13&P
0073 00
0073 00-15
TASK 5 - BALANCE TAIL ROTOR
PROCEDURE 1: EQUIPMENT INSTALLATION
a. Remove AVA blade tracking equipment from transport case. Check for possible damaged equipment and
frayed cables. Figure 1 is the typical AVA test setup configuration.
b. Install DAU in the canvas carrying case.
c. Place DAU in the CPO's seat with the connectors facing up and secure DAU using seat belts.
d. Connect the power cable (29104700) to the aircraft power receptacle (located to the right of the CPO's cyclic)
and to the DAU receptacle marked 28 Vdc.
e. Locate CADU in the front cockpit area ensuring not to obstruct the pilot's flight controls. Connect CADU to DAU
cable (29325601) to CADU and to DAU receptacle marked CADU.
PROCEDURE 2: ACCELEROMETER INSTALLATION
a. Mount accelerometer mounting bracket (29313000) on the top stud of the tail rotor gearbox flange, see figure 7.
b. Install accelerometer (28110900) on bracket with the connector pointing up.
c. Connect accelerometer cable (either 29105600 or 29105605) to accelerometer.
CAUTION
Keep accelerometer cable snug around tail boom to
ensure that cable does not contact tail rotor. The
cable should have a proper bend radius at the
accelerometer and not pulled taut.
d. Route cable downward on the right side of tail boom from tail rotor and secure along tail boom HF antenna with
tie-down straps. If antenna is not installed, wrap cable around tail boom.
e. Connect accelerometer cable to the DAU receptacle marked ACC4.
PROCEDURE 3: OPTICAL RPM SENSOR INSTALLATION
a. Remove the two screws at the base of the tail rotor gearbox where the tail cone attaches and just below the oil
level sight glass, see figure 7.
b. Mount optical RPM sensor mounting bracket (29198600) at the base of the gearbox using the two screws. The
rectangular hole should be toward the left side of the aircraft.
c. Mount optical RPM sensor (29314700) to the bracket, facing the tail rotor.
d. Connect the optical RPM sensor cable to the optical RPM sensor and route the optical RPM sensor cable the
same as the accelerometer cable (procedure 2).
e. Connect the optical RPM sensor cable to the DAU receptacle marked TACHO 2.
NOTE
If there is any tape remaining from previous balance
routines, this must be completely removed to ensure a
clear and accurate tachometer signal to the DAU.
f. Place a single, 3-inch strip of reflective tape on the inside of one of the tail rotor blades, figure 7, at the
approximate location of the beam from the optical RPM sensor. The reflective tape must not extend around or
onto the leading edge.
g. Proper alignment of the tape can be verified by applying 28 Vdc power to the DAU and rotating the tail rotor
until the taped blade passes in front of the optical RPM sensor. A red LED on the back of the sensor will light if
the sensor picks up a return from the reflective tape.
