As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
FLIGHT CREW REPORTED ISSUE AT 3000 FEET WHEN NOSE GEAR FAILED TO EXTEND. ATTEMPLTED TO EXTEND GEAR TWICE WITH SAME RESULTS. ACCOMPLISHED MANUAL LANDING GEAR EXTENSION ON APPROACH, AN EMERGENCY WAS DECLARED. LANDING GEAR NOT LOCKED, NOSE WHEEL RED INDICATION. AIRCRAFT WAS GROUNDED. MAINTENANCE FOUND DOWNLOCK PROXIMITY SENSOR 20GA2 ELECTRICAL CONNNECTOR LOOSE AND NOT LOCKED. SECURED THE CONNECTOR IAW MM 32-31-00 AND ACCOMPLISHED SATISFACTORY OPERATIONAL CHECK.