What was found
DURING POST FLIGHT INSPECTION, FOUND SEVERAL SPINNER SCREWS LOOSE, AND ONE MISSING THAT HAD BEEN THERE AT PREFLIGHT. REMOVED SPINNER TO INVESTIGATE, AND FOUND FORWARD BULKHEAD CRACKED, WITH MANY SMALL PIECES MISSING. DURING PROPELLER REMOVAL TO REPLACE DAMAGED PARTS, FOUND PROPELLERS TO INSTALLED AND CLOCKED CORRECTLY, INCLUDING BOLT TORQUES IAW MFG MM. INSPECTION FOUND PROPELLER UNDAMAGED, AND IN AIRWORTHY CONDITION. NO APPARENT CAUSE COULD BE DETERMINED, DEFECTIVE PART FROM MFG SUSPECTED. TT 227 HOURS. ACCUMULATED IN LESS THAN A THREE MONTH PERIOD. PILOT REPORTED NO VIBRATION OR ANY OTHER OPERATIONAL CONCERNS.