As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
ACFT EXPERIENCING SHUTTER, BUFFETING SOUND, SMALL LOSS IN POWER SOMETIMES VERY SMALL OVERSPEED ON ENGINE TACH. CONTACTED MFG AND IT WAS DECIDED THE CLUTCH SHOULD BE REPLACED AS IT WAS TYPICAL WITH OTHER ACFT EXPERIENCING CLUTCH SLIPPAGE. ONCE REMOVED THE CLUTCH FELT ROUGH. OIL LEVEL NORMAL.