What was found
RECEIVED LOW OIL PRESSURE MSG ON RIGHT ENGINE. OIL PRESSURE CONTINUED TO DROP. SHUT DOWN ENGINE. 1 HPT STAGE-2 BLADE FRACTURED AT AIRFOIL MID-SPAN. TRAILING EDGE COOLING HOLES PARTIALLY PLUGGED DUE TO INTERNAL SULFIDATION. THIS SULFIDATION CHOKES-OFF COOLING AIR FLOW WITHIN THE BLADE AIRFOIL, THEREBY OVERHEATING PARENT MATERIAL AND LEADING TO FRACTURE. 3 ADJACENT BLADES SUFFERED MECHANICAL FRACTURE FROM SULFIDATED BLADE. THIS CAUSED A LARGE UNBALANCE/VIBRATION THAT CRACKED AN EXTERNAL OIL LINE RESULTING IN THE SHUTDOWN. THE INTERNAL SULFIDATION IS RESULT OF TURBO-TIP CONTAMINATION DURING BLADE MANUFACTURE, OR REPAIR.