What was found
FIELD MAINT REPORTED NR 1 ENGINE HAD FOREIGN OBJECT DAMAGE TO NR 1 ENG COMPRESSOR. MECH EXAMINED TURBINE FOR DAMAGE PER MAINT INSTRUCTIONS. DAMAGE FOUND ON TURBINE NR 1 WHEEL AND ENG REMOVED AND RETURNED FOR REPAIR. UPON TEARDOWN, FOUND NR 1 TURB WHEEL HAD DAMAGE BEYOND REPAIR ON WHEEL BLADE TIPS DUE TO SULFIDATION CAUSING OTBD L/E OF BLADE TIPS TO ACCUMULATE DEPOSITS FROM CONTAMINANTS IN ATMOSPHERE, AND POSSIBLY CAUSED BY OTHER CONDITIONS. REF RR 250/C30, CSL 3161. AFFECTED TURBINE WHEEL REMOVED FROM SERVICE AND REPLACED. TURBINE REPAIRED, RETURNED TO SERVICE. (X)