As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON VISUAL INSPECTION, FOUND THE LEFT ENGINE CARBURETOR HEAT AIRBOX BACKPLATE (WELD) STEEL STAPLES WEARING THROUGH ALUMINUM WALL DUE TO AIR VIBRATION WHEN CARB HEAT DOOR IS FULLY DEFLECTED. SHOULD THE STAPLES WEAR THROUGH THE WALL ENTIRELY, FELT DOOR-STOP COULD BE SUCKED DIRECTLY INTO VENTURI OF CARBURETOR CAUSING AN INDUCTION BLOCKAGE AND ENGINE FAILURE. AIRCRAFT USED DAILY FOR FLIGHT TRAINING WITH AN AVERAGE OF 100 HOURS OF FLIGHT TIME EVERY 90 DAYS.