What was found
PILOT REQUESTED A FLIGHT TRACK CHECK OF THE MAIN ROTOR SYSTEM DUE TO A CHANGE IN VIBRATION LEVELS WHICH HAD CHANGED FROM LAST FLIGHT. THE TRIM TABS WERE CHECKED WITH THE RECORD MADE FROM THE LAST TRACKING FLIGHTS WITH ONLY A MINOR CHANGE. THE BLADE TRACKING EQUIP INSTALLED AND HELICOPTER FLOWN. THERE WERE SEVERAL READINGS OBTAINED FROM THIS FLIGHT AND THEY WERE NOT CONSISTENT. INSP FOUND BOTH FEATHERING BEARINGS DELAMINATED AND THE BEARING INNER MEMBERS SEPARATED ON THE RED BLADE. BEARINGS REPLACED PER MFG'S COMPONENT O/H AND RM. HELICOPTER TRACKED AND BALANCED WITHOUT ANY PROBLEMS AND RELEASED TO SERIVCE. LAST INSPECTION 67.2 HRS AND 5 MONTHS PRIOR, FOUND NO DEFECTS WITH THE BEARINGS.