TASK 9 - ENGINE OUTPUT SHAFT BALANCING
The following procedures provide instructions for the balancing of the engine output shafts of the UH-60L/UH-60A/EH-
60A helicopters with shaft balance assembly installed using the AVA equipment.
PROCEDURE 1: CHECK BALANCE
Perform task 8, procedures 1 and 2: Equipment Installation (omit oil cooler connection if oil cooler assembly is
not to be tested).
Make sure all cables are secure on helicopter using
tiedown straps per Appendix D of TM 1-1520-237-23.
Perform task 8, procedure 3: Engine Output Shafts and Oil Cooler Testing (disregard all references to the oil
cooler if the oil cooler assembly is not to be tested).
Vibration levels shall be 0.50 ips or less. If vibration levels are within this range, engine output shaft is
balanced. Remove accelerometers, cables, and brackets from the input modules. If vibration level is between
0.5 and 2.0 ips, balance engine output shaft in accordance with the following procedure. If vibration level is
greater than 2.0 ips, replace output shaft using procedures in TM 1-1520-237-23.
Figure 22. Engine Output Shaft Balance Bolt Configuration
PROCEDURE 2: OPTICAL TACHOMETER SENSOR INSTALLATION
Turn off all electrical power.
Open engine cowling.
Remove engine air inlet (refer to TM 1-1520-237-23).
Remove crotch assembly from engine (refer to TM 1-1520-237-23).