What was found
(CAN) RUBBING SOUNDS COMING FROM POWER TURBINE AREA CAUSED BY CONTACT BETWEEN FACE OF 2ND STAGE POWER TURBINE DISK, SEAL & COVER OF PT SHAFT HOUSING ASSY. CONTACT AROSE BECAUSE TEE HEAD LUGS SECURING SEAL & COVER TO PT SHAFT HOUSING FRETTED THROUGH FLANGE RELEASING SEAL AND COVER, ALLOWING SEAL TO MOVE REARWARDS & CONTACT FACE OF PT 2 DISK. ALL OF SLOTS IN PT SHAFT HOUSING ASSY HAVE HEAVY FRETTING WEAR, EITHER COMPLETELY THROUGH OR ALMOST COMPLETELY THROUGH FLANGE. THIS MEANS THAT 4 RIVETS WHICH BROKE, RELEASING TEE HEADED LUGS, FAILED TOWARDS END OF PROCESS. RIVET FAILURE WAS A RESULT OF WEAR & FRETTING & WAS NOT CAUSE OF IT.