As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INSPECTION, FOUND THE TWO SCREWS WHICH SECURE THE CARBURETOR HEAT BUTTERFLY VALVE TO THE SHAFT WERE LOOSE. UPON REMOVAL, FOUND SCREWS WORN APPROXIMATELY 80 PERCENT THROUGH. SUBMITTER STATED APPEARS THEY HAD BEEN LOOSE FOR SOME TIME. FAILURE OF SCREWS COULD CAUSE LOSS OF POWER DUE TO RESTRICTION OF AIR FLOW AND INJESTION OF SCREWS INTO ENGINE.