What was found
THE GEAR DOOR OPEN LIGHT REMAINED ON WHEN GEAR WAS EXTENDED FOR LANDING ON APPROACH. A GO-AROUND WAS PERFORMED WHILE COMPLYING WITH ABNORMAL PROCEDURES. THE GEAR DOOR OPEN LIGHT REMAINED ON. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE D1-30 LEFT GEAR DOOR PROXIMITY SENSOR FACE DAMAGED. THE SENSOR WAS REMOVED AND REPLACED. A GEAR SWING WAS PERFORMED AND OPERATION CHECKED GOOD. THE GEAR DOORS WERE INSPECTED AND NO DAMAGE WAS FOUND.