As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
WHEN BOLT WAS REINSTALLED AND PROPELLER TORQUE APPLIED, THE BOLT BROKE. FURTHER INSPECTION OF THE BOLT REVEALED A MANUFACTURER'S DEFECT. THE BOLT CHANGES FROM COARSE THREAD TO FINE THREAD. THERE ARE NO LOG BOOK ENTRIES SHOWING THE BOLT EVER BEING CHANGED OUT. THE CHANGE OVER FROM COARSE TO FINE THREAD ALSO NARROWS THE DIAMETER OF THE BOLT.