What was found
(CAN) OVER A 6 WEEK PERIOD, 4 TAIL ROTOR BLADES HAVE BEEN REMOVED FOR SMALL POCKET CRACKS. EACH TIME A BLADE WAS REPLACED, THE T/R WAS REBALANCED TO 0.1 IPS. THE CRACKS OCCURRED ON TWO DIFFERNT ENT T/R ASSEMBLIES. A SPECTRUM RUN FOR VIBRATION IN THE TAIL SECTION SHOWED NO ABNORMALTIES AND RIGGING WAS FOUND TO BE WITHIN ACCEPTABLE LIMITS. MANUFACTURER WAS NOTIFIED AND BLADES RETURNED FOR EVALUATION AND REPAIR.