As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) PROPELLER BOLTS WERE BEING INSTALLED AND TORQUED TO THE SPECIFIED VALUE OF 25 - 30 POUNDS FOOT. AS THE TORQUE WAS REACHING APPROXIMATELY 27 FOOT POUNDS, THE BOLT BROKE. THE BREAK WAS WHERE THE THREADS MEET THE GRIP. A SECOND BOLT WAS TORQUED AND IT BROKE AT APPROXIMATELY THE SAME TORQUE VALUE AND AT THE SAME LOCATION.