As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AT FL310 DURING CRUISE A LOUD HUM ACCOMPANIED BY A VIBRATION OCCURRED ON ENGINE NR 3. PERFORMED ABNORMAL IN-FLIGHT ENGINE SHUTDOWN PROCEDURE PER 727 AOM. REMOVED AND REPLACED NR 3 ENGINE ASSEMBLY IAW ASTAR B-727 MTM 71.1. OPS CHECKED GOOD, OK FOR SERVICE.