As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING INSTALLATION AND TIGHTENING OF BOLTS THAT SECURE THE FORWARD ENGINE MOUNT TO THE PYLON, ONE BOLT BROKE IN TWO AND ANOTHER BOLT STRIPPED. THIS OCCURRED PRIOR TO THE BOLTS REACHING FINAL TORQUE. THIS IS CURRENTLY BEING INVESTIGATED BY BOEING AND IS ALSO BEING TRACKED BY GEES SAFETY PRODUCT MANAGEMENT TEAM (SPMT).