What was found
AIRCRAFT WAS NOT GROUNDED: AFTER TAKEOFF, WHEN POSITIONED GEAR HANDLE TO OFF POSITION, THE GEARDOOR AMBER LIGHT ILLUMINATED WITH ENGINE INDICATION AND CREW ALERTING SYSTEM MESSAGE OF "GEAR DOOR". FOLLOWED QUICK REFERENCE HANDBOOK PROCEDURE. WHEN GEAR HANDLE TO UP POSITIONED, GEAR DOOR LIGHT EXTINGUISHED. FLIGHT CONTINUED TO DESTINATION WITH NO EMERGENCY DECLARED. MAINTENANCE PERFORMED FAULT ISOLATION MANUAL PROCEDURE 32-30-00-0815-813, NO FAULT FOUND, CYCLED GEAR SEVERAL TIMES, ALL INDICATIONS REMAINED NORMAL AND REPLACED LEFT MAIN LANDING GEAR DOOR ACTUATOR AS PRECAUTIONARY. MAINTENANCE ALSO PERFORMED SATISFACTORY OPERATIONAL CHECKS.