What was found
DURING CLIMB FROM 14,000 FEET THE (MAIN CARGO DOOR NOT CLOSED) LIGHT ILLUMINATED. THE FLIGHT CREW DECLARED AN EMERGENCY AND RETURNED TO DEPARTURE. ON DECENT THE LIGHT WENT OFF AT 12,000 FEET. AN UNEVENTFUL LANDING WAS MADE AT DEPARTURE. THE MAIN CARGO DOOR WAS VERIFIED TO BE CLOSED AND LOCKED AND THE MAIN CARGO DOOR INDICATING SYSTEM WAS DEFERRED. INSPECTION REVELED THAT THE MAIN CARGO DOOR LATCH LOCK SWITCH WAS OUT OF ADJUSTMENT. THE SWITCH WAS ADJUSTED AND THE AIRCRAFT WAS RETURNED TO SERVICE. (K)