What was found
AFTER DEPARTING, UPON INITIAL CLIMB OUT, AT 1,000, WE HEARD SOME NOISE FROM THE DOOR AREA, AS IF SOMETHING HAD BECOME UNLATCHED, AND WE SIMULTANEOUSLY SAW A YELLOW DOOR INDICATION ON THE STATUS SYNOPTIC PAGE. WE DECLARED AN EMERGENCY, CONTINUED OUR CLIMB TO 2,000', WHERE WE ENTERED A DOWNWIND LEG FOR LANDING ON THE RUNWAY OF OUR CHOOSING, AS WE WERE CLEARED TO LAND ON ANY RUNWAY BY THE CONTROL TOWER. WE LANDED WITH NO DIFFICULTIES. AIRCRAFT WAS REMOVED FROM SERVICE AND MAINTENANCE INSPECTED THE MAIN ENTRANCE DOOR (MED) WITH NO DISCREPANCIES NOTED. OPERATIONAL CHECKED SEVERAL TIMES WITH NO DEFECTS NOTED. ALL WORK PERFORMED IAW AMM 52-11-00-010-801 & 52-11-0-410-801. NOTE: CREW MENTIONED TO MAINTENANCE THAT THE MED HANDLE MAY NOT HAVE BEEN FULLY DOWN. AIRCRAFT HAS FLOWN 14 ADDITIONAL LANDINGS TO DATE WITH NO FURTHER FAULTS NOTED.