What was found
THE LT MLG UNSAFE LIGHT REMAINED ILLUMINATED AFTER GEAR EXTENSION ON APPROACH. ABNORMAL PROCEDURES WERE COMPLIED WITH AND THE EMERGENCY GEAR EXTENSION LEVER WAS PULLED. A TOWER FLY-BY WAS PERFORMED AND THE GEAR WAS CONFIRMED DOWN. THE AIRCRAFT LANDED WITHOUT INCIDENT. MAINTENANCE FOUND THE LT MLG DOWNLOCK SWITCH CANNON PLUG DIRTY. THE PLUG WAS CLEANED. A SYSTEM TEST ON THE LANDING GEAR LIGHTS CHECKED GOOD IAW MM 32-60-1, PAGE 201.