As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING POWER REDUCTION FROM TAKE-OFF POWER TO CLIMB POWER, A (POP) WAS HEARD AND ONE OF THE ENGINES BEGAN RUNNING ROUGH. THERE WAS NO INSTRUMENT/GAGE INDICATION AS TO WHICH ENGINE. AIRCRAFT LANDED WITH OUT INCIDENT. POST FLIGHT EXAMINATION FOUND NR 1 ENGINE, NR 6 CYLINDER HEAD HAD SEPARATED.