What was found
AIR SHUTTLE 7899 - PDX-PSC - AIRCRAFT WAS EN ROUTE TO PSC WHEN PILOTS NOTICED THE CARGO DOOR ANNUNCIATOR HAD ILLUMINATED. PILOTS DECLARED AN EMERGENCY AND PROCEEDED TO LAND WITHOUT INCIDENT. CARGO DOOR WAS FOUND TO BE CLOSED AND LOCKED. THE ANNUNCIATOR SYSTEM WAS SUBSEQUENTLY MEL'D. AIRCRAFT RETURNED TO SERVICE. IN SUBSEQUENT MX THE SWITCH WAS CLEANED AND RIGGED, OPS CHECK GOOD. (M)