As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
RECEIVED TURBINE FROM FIELD TO REPAIR FOR HIGH FREQUENCY AND VIBES. REMOVED OUTER COMBUSTION CASE FROM TURBINE TO INSPECT FOR HIGH FREQUENCY AND FOUND 1ST STAGE WHEEL BLADES TO HAVE BEEN ATTACKED BY SULPHADATION. MFG SHOULD USE THE NEW GENERATION OF COATING TO STOP THIS PROBLEM.