As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE SPOT WELD WHICH ATTACHES THE BUTTERFLY VALVE TO THE SHAFT BROKE WHICH ALLOWED THE VALVE TO BE SUCKED UP INTO THE CARBURETOR AND BLOCK OFF THE AIR TO THE ENGINE. THIS CAUSED THE ENGINE RPM TO DROP TO 700 RPM. THE PILOT LANDED IN A PLOWED FIELD, NO FURTHER DAMAGE TO AIRCRAFT.