What was found
TAIL ROTOR GEAR BOX & SERVO ASSY RECEIVED WITH A WRITE-UP OF UNABLE TO CHANGE PITCH OF BLADES BY HAND DURING INSPECTION.. UPON RECEIPT IN SHOP PITCH CHANGE SHAFT MOVED FREELY BY HAND. T/R G/B WAS DISASSEMBLED AND FOUND OK. T/R G/B SERVO WAS CHECKED AND FOUND BINDING IN 2DN STAGE PILOT VALVE. SERVO DISASSEMBLED AND FOUND SCORING ON PILOT VALVE. HYDRAULIC FLUID SENT FOR ANALYSIS. OPERATOR NOTIFIED OF POSSIBLE CONTAMINATED HYDRAULIC SYSTEM. ON TEARDOWN OF PILOT VALVES, BOTH WERE FOUND HEAVILY SCORED. FLUID REPORT REPORTED HEAVY CONTAMINATION.