As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE MAINTENANCE, THE NR 2 ENGINE FILLED THE CABIN WITH SMOKE. MAINTENANCE INSPECTED AND REPLACED THE NR 2 ENGINE. TEAR DOWN REPORT FROM ROLLS ROYCE INDICATED THE NR 4 CARBON SEAL WAS FOUND WITH BROKEN CARBON SEGMENTS. THE ENGINE CONDITION WAS ADDRESSED THROUGH ENGINE REPAIR AND SB UPGRADE INCLUDING SB 72-348 NEW TANDEM NR 4 CARBON SEAL.