What was found
ON DEPARTURE FROM MKE CREW REPORTED A BUFFETING NOISE FROM THE NOSE OF THE AIRCRAFT, SOUNDED LIKE THE NOSE GEAR DOOR WAS OPEN, BUT WERE NOT GETTING A "NOSE GEAR DOOR OPEN" ANNUNCIATOR. CREW PERFORMED A PASS DOWN THE RUNWAY AND MAINTENANCE WAS ABLE TO VERIFY ONE NOSE GEAR DOOR WAS OPEN. CREW CIRCLED AIRPORT TO BURN OFF FUEL TO GET BELOW MAX LANDING WEIGHT, THEN LANDED AT MKE WITHOUT INCIDENT. AIRCRAFT WAS PLACED ON JACKS AND NOSE GEAR LINKAGE WAS INSPECTED. FOUND LEFT GEAR DOOR ACTUATOR LINK ASSY WAS UNLATCHED. LATCHED LINK ASSY AND ALL OPERATION WAS NORMAL. SUSPECT LEFT LINK ASSY WASN'T LATCHED AFTER MANUAL RELEASE FOR PREFLIGHT. INSPECTED "NOSE GEAR DOOR OPEN" ANNUNCIATOR SYSTEM AND FOUND LEFT NOSE GEAR DOOR PROXIMITY SWITCH FAILED. REPLACED NOSE GEAR DOOR SWITCH HARNESS. OPS CHECK GOOD.