CL65 EXPERIENCES PAX DOOR WARNING ON INITIAL CLB. RETURN TO DEP ARPT.

Narrative

DURING TAKEOFF CLB FROM ZZZ THROUGH APPROX 5000 FT MSL; 'PAX DOOR LATCH' CAUTION MSG ACTIVATED ON ED1 WITH ASSOCIATED AURAL SINGLE-CHIME. APPROX 30 SECONDS LATER; 'PAX DOOR' WARNING MSG AND ASSOCIATED AURAL TRIPLE-CHIME AND VOCAL 'DOOR' ACTIVATED. AS PF; I TOOK CTL OF COM #1 (ATC) AND COMMANDED FO TO COMPLETE THE QUICK REFERENCE HANDBOOK (QRH) PROC APPROPRIATE WITH THE 'PAX DOOR' WARNING. PRESSURIZATION; ACFT CONTROLLABILITY; AND SOUNDS WERE NORMAL. I DECLARED AN EMER WITH DEP CTL AND STATED MY INTENTION TO RETURN TO ZZZ. I RECEIVED CLRNC TO LEVEL AT 7000 FT AND VECTORS FOR A RIGHT DOWNWIND. AFTER FO COMPLETED QRH EMER CHKLIST; IT DIRECTED 'LAND AT THE NEAREST SUITABLE AIRPORT.' ZZZ WAS UNQUESTIONABLY THE NEAREST SUITABLE AIRPORT. I DECLINED ARFF EQUIP AND DID NOT DEEM AN EVACUATION AS NECESSARY UNDER THE CIRCUMSTANCES. NORMAL CHKLISTS WERE COMPLETED AND A NORMAL LNDG WAS MADE WITHOUT INCIDENT. PAX WERE DEPLANED AT GATE VIA NORMAL PROCS. FLT ATTENDANT INSPECTED DOOR CAMS ON TAXI-IN AND OBSERVED ALL GREEN WITNESS MARKS PROPERLY ALIGNED; INDICATING DOOR WAS PROPERLY CLOSED. CONTRACT MAINT CYCLED THE PAX DOOR AND COULD NOT DUPLICATE THE PROB. THE ACFT WAS SIGNED OFF FOR FURTHER FLT WITH NO RESTR. ON SUBSEQUENT FLT 'PAX DOOR LATCH' CAUTION MSG ACTIVATED AND REMAINED ON DURING ENTIRE FLT. MAINT PERSONNEL INSPECTED DOOR AND FOUND WORN/MALADJUSTED PARTS.