What was found
TAIL ROTOR GEARBOX OUTPUT SHAFT RETAINING NUT, PN MS1414526, WAS FOUND SLIPPING AND UNDERTORQUED. DURING 100-HOUR INSPECTION, TAIL ROTOR BLADE ROTATION NOTED MOVING MORE THAN NORMAL GEAR BACKLASH. TEAR DOWN OF THE T/R GEARBOX REVEALED NUT TORQUED TO 75 INCHES/POUNDS VS 250 AND WASHER AND KEY WERE WORN. THIS GEARBOX WAS NOT SUBJECT TO AD 94-17-07. THE MANUFACTURER DOES NOT PUBLISH INSPECTION CRITERIA IN THIS AREA. A/C TT 6229.3 (X)