As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) DURING CLIMB, THE ENGINE EXHIBITED VIBRATION AND LOUD BANGING NOISES ON COMMANDED POWER MODULATION. ENGINE POWER WAS REDUCED TO FLIGHT, IDLE AND THE AIRCRAFT DIVERTED TO POINT OF DEPARTURE. THE HYDROMECHANICAL FUEL CONTROL UNIT WAS SUBSEQUENTLY REPLACED.