As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
UPON CARRYING OUT FORWARD FUSELAGE INSPECTION (TASK 112-DH1) I FOUND A DAMAGED B-NUT ON THE OXYGEN LINE THAT RUNS FROM THE CREW OXYGEN FILL PORT TO THE CREW OXYGEN TANK. THE B-NUT WAS CRACKED IN THREE DIFFERENT SPOTS WHICH INDICATES POSSIBLE EVIDENCE OF EXCESSIVE TORQUE BEING PLACED ON THE B-NUT. REFERENCE DWG 21603 A, P/N: 21603-1.