What was found
(CAN) WHEN PERFORMING A ENGINE CHECK RUN, AFTER THE INSTALLATION OF A TURBINE, EXCESSIVE ENGINE GROWLING/HOWLING WAS DETECTED. UPON FURTHER INSPECTION WITH VIBRATION EQUIPMENT A VIBRATION WAS DETECTED IN THE TURBINE ASSY. IN CONTACT WITH THE ENGINE, TURBINE SUPPLIER, THE COUPLING SHAFT WAS THE NOTED PROBLEM. COUPLING SHAFT REPLACED AND ENGINE CHECK RUN COMPLETED WITH NO FURTHER DEFECTS. ENGINE SHOP NOTIFIED OF THE REPAIR AND THEY STATED THAT THIS WAS A EARLIER PROBLEM WITH PREVIOUS NEW COUPLING SHAFTS.