What was found
(CAN) ON APPROACH, THE PITCH CONTROL FELT STIFF FOLLOWING AUTOPILOT DISCONNECT PRIOR TO LANDING. AT ABOUT 400 FEET ALTITUDE, THE CREW DISCONNECTED THE AUTOPILOT. THE AIRCRAFT THEN PITCHED NOSE DOWN. THE CREW REPORTED THAT FOLLOWING THE PITCH DOWN THEY FAUGHT WITH THE AIRCRAFT UNTIL AN UNBINDING FEELING HAPPENED AND REGAINED CONTROL OF THE AIRCRAFT. THE CREW DECLARED AN EMERGENCY, PERFORMED A GO-AROUND AND LANDED WITHOUT FURTHER INCIDENT. INVESTIGATION ON-GOING.