What was found
HIGH N2 VIBRATION ON NR 2 ENGINE. ONE HPT STAGE-2 BLADE HAD CORDWISE AIRFOIL FRACTURE AT THE MID-SPAN. THIS WAS THE RESULT OF INTERNAL SULFIDATION THAT CHOKES-OFF COOLING AIR FLOW WITHIN THE BLADE AIRFOIL. THIS RESULTS IN OVERHEATING OF THE PARENT MATERIAL AND SUBSEQUENT AIRFOIL FRACTURE. ALL OF THE REMAINING STAGE-2 BLADES SUFFERED RESULTANT DAMAGE IN THE FORM OF NICKS & TEARS. THE INTERNAL SULFIDATION IS THE RESULT OF TURBO-TIP CONTAMINATION DURING BLADE MANUFACTURE, OR REPAIR. PRATT & WHITNEY HAS MADE PROCESS CORRECTIONS TO ELIMINATE THIS CONTAMINATION.