TM 55-1520-240-T
2-1.3 VIBRATION FREQUENCY IDENTIFIED AS 225 RPM (1 /REV) (Continued)
2-1.3
HAVE PILOT PERFORM GROUND
RUN AT 225 RPM, FLAT PITCH.
MEASURE GOUND TRACK ON
BOTH ROTORS (TM 55-1520-
240-23) WERE BLADES WITH-
REPLACE PITCH LINKS FOUND
TO HAVE WORN BEARINGS.
PERFORM THIS TASK AGAIN
FROM THE BEGINNING.
CHECK PITCH LINK BEARINGS.
ARE ANY PITCH LINK BEARINGS
WORN?
IN 3/8 INCH OF EACH OTHER?
HAVE PILOT ESTABLISH STABLE HOVER TUNE VIBREX TO 225 RPM. RE-
CORD FORWARD ROTOR vERTICAL AND LATERAL AND AFT ROTOR VERTl-
CAL AND LATERAL VIBRATIONS IN IPS AND CLOCK ANGLES. RECORD
HOVER TRACK ON BOTH ROTORS. WERE ALL MEASURED VIBRATION
LEVELS WITHIN RANGES OF TABLE 2-1.3?
LAND HELlCOPTER. SHUT
DOWN ENGINES. CHECK 130
KNOT BLADE TRACK. WERE
BLADES WITHIN 1/2 INCH OF
EACH OTHER?
HAVE PILOT ESTABLISH 130 KNOT CRUISE PROFILE. RECORD FWD VERTl-
CAL AND LATERAL AND AFT VERTICAL AND LATERAL VIBRATIONS IN IPS
AND CLOCK ANGLE RECORD IN-FLIGHT TRACK ON BOTH ROTORS ARE Vl-
BRATION LEVELS WITHIN RANGES OF TABLE 2-1.3?
CALCULATE PITCH LINK AD-
JUSTMENT TO BRING BLADES
WITHIN 1/2 INCH OF EACH
OTHER AT 130 KNOTS. USE
CALCULATED ADJUSTMENT
LAND HELlCOPTER. SHUT
DOWN ENGINES CHECK RE-
USE PITCH LINK ADJUSTMENT
CORDED HOVER BLADE TRACK,
= 0 MARKS FOR INPUT TO PC
WERE BLADES WITHIN 1/2
PITCH LINK-LATERAL PRO-
INCH OF EACH OTHER?
GRAM.
1/REV VIBRATION LEVELS ARE
SATISFACTORY.
AS INPUT TO PC PITCH LINK-
LATERAL PROGRAM.
USING PC PITCH LINK-LATERAL PROGRAM, DETERMINE VIBREX TIP WEIGHT
CORRECTION TO COMPENSATE FOR ANY PITCH LINK ADJUSTMENT. AD-
JUST TIP WEIGHTS AS NECESSARY (TM 55-1520-240-23). HAVE PILOT
ESTABLISH STABLE HOVER. MEASURE FORWARD AND AFT ROTOR VIBRA-
TIONS. ARE ALL VIBRATION LEVELS WITHIN RANGES OF TABLE 2-1.3?
CALCULATE PITCH LINK AD-
JUSTMENT TO BRING BLADES
WITHIN 1/2 INCH OF EACH
ADJUST VIBREX BLADE TIP WEIGHTS (TM 55-1 520-240-23) TO CORRECT
LATERAL VIBRATION USING LATEST HOVER INPUT DATA IN PC PITCH
LINK-LATERAL PROGRAM. MAKE NECESSARY ADJUSTMENTS AND PER-
FORM THIS TASK AGAIN BEGINNING WITH STABLE HOVER.
ARE RECORDED VERTICAL VI
BRATION LEVELS WITHIN
RANGES OF TABLE 2-1.3?
OTHER. USE CALCULATED AD-
JUSTMENT AS INPUT TO PC
PITCH LINK-LATERAL PRO-
GRAM.
REPLACE PITCH LINKS FOUND
TO HAVE WORN BEARINGS.
CHECK PITCH LINK BEARINGS.
PERFORM THIS TASK AGAIN
ARE ANY PlTCH LINK BEARINGS
INSPECT ROTOR HEAD ASSY.
FROM THE BEGINNING.
WORN?
REF TM 55-1520-240-23.
TABLE 2-1.3. NORMAL ONE/REV VIBRATION LEVELS
FWD AND AFT ROTOR A T 225 RPM
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