What was found
(CAN) FOLLOWING A REPAIR, THE ENGINE FAILED TO START AND WITH INVESTIGATION WAS DISASSEMBLE AND 2 MODULES, M02 AND M03, SENT TO ENGINE MFG FOR REPAIR. ON RECEIVING REPAIR/INSPECTED MODULES, ENGINE TECH REP WAS ON SITE TO ASSEMBLE ENGINE AND THEN IT WAS INSTALLED IN AIRFRAME. DURING GROUND RUN, A UNUSUAL NOISE WAS HEARD AT AROUND 70 PERCENT NG AND AS SOON AS THROTTLE WAS ADVANCED IT WOULD GO AWAY. ALSO, DURING THIS TIME A VIBRATION WAS FELT AROUND THE STARTER AND ACCESSORIES OFF THE ACCESSORY GEARBOX. ENGINE VIBRATIONS WERE MEASURED TO BE 3 TIMES THE VIBRATIONS THEY WERE PREVIOUS TO ANY REPAIRS AND TROUBLESHOOTING CONSISTED OF TRYING DIFFERENT STARTER GENERATORS AND BLEED VALVES BUT ENGINE VIBRATIONS WERE STILL 3 TIMES WORSE THAN PREVIOUS, STILL WITHIN LIMITS BUT MUCH WORSE. THE UNUSUAL NOISE STILL BEING PRESENT WAS THE CAUSE FOR CONCERN AND THE CAUSE TO REMOVE THE ENGINE AND REINSTALLED.