As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
INSPECTION OF THE CARBURETOR DETERMINED THE THROTTLE ARM BECAME LOOSE ON THE SHAFT. THIS CONDITION RESULTED IN LOSS OF CONTROL OF ENGINE RPM. THE NUT AND COTTER PIN WERE INTACT. SUSPECT THE ORIGINAL INSTALLATION WAS NOT PROPERLY INSTALLED AND TORQUED ALLOWING THE ARM TO BECOME LOOSE. IT IS SUGGESTED THAT CORRECT INSTALLATION AND TORQUE WOULD PREVENT THIS CONDITION.