What was found
ON CLIMB-OUT, BETWEEN FL240 - FL290, 3 OCCURANCES OF A LOUD NOISE IN AFT CABIN, COMBINED WITH A SHORT PRONOUNCED AIRCRAFT VIBRATION FELT THROUGHOUT THE ENTIRE ACFT, AS WELL AS THE CONTROL COLUMN. DID NOT NOTE ANY ABNORMAL ENGINE INDICATIONS OR MESSAGES. BOROSCOPE OF ENGINE REVEALED COMPRESSOR DAMAGE. REPLACED NR 2 ENGINE.