As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ENGINE REMOVED DUE TO M50 MATERIAL ON THE MAG CHIP DETECTORS. DISASSEMBLY OF THE ENGINE REVEALED THE NR 4 BEARING EXHIBITED SPALLING DAMAGE ON THE OUTER RACE. THE BEARING WAS SUBMITTED TO THE LAB FOR ANALYSIS. THE INVESTIGATION IS STILL IN PROGRESS AT THIS AGENCY.