As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CLIMB, PILOT REPORTED A LOUD NOISE AND NR 1 ENGINE VIBRATIONS. REDUCED POWER, VIBRATIONS REDUCED. TRIED TO PUT A LITTLE MORE POWER, VIBRATIONS INCREASED. RETURNED TO DEPARTURE AIRPORT. THE PRELIMINARY TROUBLESHOOTING REVEALED A LARGE TRACE OF OIL AT 9 O`CLOCK POSITION FROM REAR VIEW.