TASK 3 - TRACK AND BALANCE MAIN ROTOR IN FLIGHT
Main rotor FLIGHT track and balance should be performed when any of the following occurs:
a. In-flight vertical vibration is unacceptable.
b. Changes have been made to the track of one or more main rotor blades as a result of performing ground
c. Repairs have been made to one or more main rotor blades.
d. One or more main rotor blades have been removed and reinstalled or replaced.
e. In accordance with IETM instructions TM 1-1520-LONGBOW/APACHE (AH-64D) or TM 1-1520-238-23 (AH-
Vibration levels (vertical or lateral) of 1.2 ips and
above may cause aircraft damage. Avoid flying the
aircraft with these levels.
Avoid flying the aircraft with track spreads (high to
low blade) of 3 inches or more.
Flight Track and Vibration Limits
The AVA will show the following flight track and vibration limits:
Lateral Vibration on Ground:
Lateral Vibration in Hover:
Vertical Vibration in Forward Flight:
Ground and Hover Track:
1.5 inch high blade to low blade
Forward Flight Track:
2.0 inch high blade to low blade
It should be possible to obtain aircraft vibration within
these limits with a reasonable number of adjustment sets
(i.e., flights). Inability to do so may be a symptom of a
maintenance problem or a problem with AVA
PROCEDURE 1: EQUIPMENT INSTALLATION
a. Install test equipment (refer to task 1).
b. Turn DAU ON.
c. Turn CADU ON.
PROCEDURE 2: PERFORM FORWARD FLIGHT MEASUREMENT
a. Press QUIT until the Main Menu appears.
b. Verify that aircraft type and tail number are as desired. Highlight Flight Plan and press DO. FLIGHT is
highlighted. Press DO.
c. Press F1 Measure.
d. On the measurement screen, press F4 to toggle from LIMITS OFF to LIMITS ON. NOTE: Selection will stay
selected as long as measurements are occurring in the current flight ID. Once the measurement screen is exited,
LIMITS will reset to OFF.