What was found
ON APPROACH, THE NOSE GEAR GREEN LIGHT DID NOT ILLUMINATE, FOLLOWED BY THE RED UNSAFE LITE DURING NORMAL GEAR EXTENSION. CREW EXECUTED A MISSED APPROACH, FOLLOWED BY THE "LANDING GEAR FAILED TO EXTEND" CHECK LIST PROCEDURE AND DECLARED AN EMERGENCY. AFTER EMERGENCY GEAR EXTENSION THE NOSE GEAR GREEN LITE ILLUMINATED. ACFT LANDING WAS UNEVENTFUL. DISCREPANCY WAS ISOLATED TO FAULTY NOSE LANDING GEAR ACTUATOR. ACTUATOR WAS REPLACED AND SYS OPS CHECK WAS NORMAL. ACFT WAS RETURNED TO SERVICE.