What was found
FLIGHT NR 3897 DEPARTING ISLIP HAD TO RETURN TO FIELD WHEN DURING INITIAL CLIMB FOLLOWING GEAR RETRACTION, IT WAS NOTICED THAT THE RT MAIN GEAR UNSAFE LIGHT WAS ILLUMINATED AND A GRINDING NOISE WAS PRESENT. GEAR WAS SELECTED DOWN AND THREE GREENS WERE OBTAINED. ALL HYDRAULIC INDICATIONS WERE NORMAL. AIRCRAFT RETURNED TO FIELD. NO EMERGENCY DECLARED. MAINTENANCE FOUND THE UPLOCK ACTUATOR ON THE RT SIDE AT FAULT AND REMOVED AND REPLACED SAME. OPERATIONAL CHECKS AND LEAK CHECKS ALL GOOD. AIRCRAFT RETURNED TO SERVICE.