TM 55-1520-240-T
2-1.4 VIBRATION FREQUENCY IDENTIFIED AS 675 CYCLES/MIN (3/REV) (Continued)
2 - 1 . 4
SET TEST BOX SELECTOR
SWITCH TO LEFT. INCREASE
REPLACE COPILOT’S DYNAMIC
AND THEN DECREASE ROTOR
ABSORBER. REFLY AT 130
RPM. DOES TEST BOX METER
KNOTS. CHECK FOR VIBRA-
POINTER MOVE TOWARD EX-
TION.
TEND AND THEN RETRACT?
TIGHTEN BOLT OR REPLACE
LOOSE BEARING. REFLY AT
130 KNOTS. CHECK FOR VIBRA-
TION.
CHECK PITCH LINK BEARINGS.
ARE ANY BEARINGS WORN?
REPLACE PITCH LINK HAVING
WORN BEARINGS. REFLY AT
130 KNOTS. CHECK FOR VIBRA-
TION.
CHECK SWASHPLATE AND
UNIBALL ASSEMBLIES FOR
REPLACE WORN BEARINGS OR
BEARING WEAR. ARE ANY
UNIBALLS. REFLY AT 130
BEARINGS OR UNIBALLS
KNOTS. CHECK FOR VIBRA-
WORN?
TION.
TIGHTEN BOLTS TO REQUIRED
CHECK PYLON SPLICE BOLTS.
TORQUE. REFLY AT 130
ARE ANY LOOSE?
KNOTS. CHECK FOR VIBRA-
TION.
CHECK ALL TRANSMISSIONS
TO LOCATE TRANSMISSION
WITH LOOSE BOLTS. TIGHTEN
BOLTS TO REQUIRED TORQUE.
REFLY AT 130 KNOTS. CHECK
FOR VIBRATION.
END OF TASK
Change 5
2-11
