As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(AU) PART STSBG013-1 HEX HEAD BOLT FOUND INSTALLED IN THE REAR ENGINE MOUNT. THE BOLT HAD BEEN SUBSTANTIALLY GROUND DOWN OF MATERIAL AFT OF THE THREAD AREA. THE GRINDING HAD BEEN PERFORMED BY A ROTARY DISK AND WAS NOT UNIFORM ON THE CIRCUMFERENCE. PART NR 347257 BOLT IS CALLED IN THE MANUFACTURERS IPC. THERE IS NO SUBSTITUTION ALLOWED.