TM 1-1520-238-T-4
Change 9
5–35
SECTION III.
TROUBLESHOOTING PROCEDURES
5–17.
MAIN ROTOR TRACK AND BALANCE USING AVA EQUIPMENT
5–17
a. GENERAL INSTRUCTIONS
1. Track and balance of main rotor blades should be performed when any of the following occurs:
One or more blades have been changed.
One or more tip caps have been changed.
One or more pitch control rods or rod end bearings have been changed.
The main rotor blades have been removed and the hub has been disassembled.
As per applicable maintenance manuals.
2. A typical track and balance mission from start to finish includes the following:
Phase main rotor blades (TM 1-1520-238-23).
NOTE
Phasing the main rotor blades cannot be emphasized enough, this is the base
starting point for track and balance and if not performed, will not allow track and
balance to be completed in a timely manner.
Installation of the Aviation Vibration Analyzer (TM 1-1520-238-23).
Recommended steps prior to aircraft operations (para 5–18).
NOTE
Tail rotor balance should be accomplished before any in-flight checks are
performed. The tail rotor procedure can be performed during a ground run. If the
tail rotor is wired, take the measurements during the first ground run, and make
the adjustments and check the balance again on the next ground run.
Ground track and adjustments (para 5–19).
Initial check and adjustments (para 5–20).
Flight check and adjustments (para 5–21).
3. There may be cases when the aircraft can be flown to check the in-flight-vibrations, without performing the
ground work. The following are some examples when this can be done:
NOTE
If the following procedures do not obtain proper results, refer to paragraph 2 and
comply with all required steps to accomplish rotor track and balance.
Aircraft is written up for an in-flight one per rev vibration. It is possible that with utilizing the
FLIGHT flight plan the aircraft can be brought back into limits.
One blade is changed and it may be possible to utilize the FLIGHT flight plan and adjust the rotor
and bring it into limits.
END OF TASK
