As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DECLARED EMERGENCY DUE TO LANDING GEAR NOT EXTENDING AFTER SELECTOR HANDLE WAS MOVED DOWN. SYSTEM WAS FAULTING THE RH GEAR DOOR OPEN PROX SENSOR. ALT. GEAR EXTENSION PERFORMED. CORRECTIVE ACTION: DEFERRED GEAR RETRACTION SYSTEM PER MEL. AIRCRAFT WILL POSITION FERRY TO DTW. LATER, REPLACED PROXIMITY SENSOR 34GA, AND MAIN GEAR DOOR LEFT AND RIGHT HINGE FITTINGS.