As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
NR 3 CYLINDER HAD A CRACK FROM OUTSIDE OF CYLINDER THROUGH INTO COMBUSTION CHAMBER, APPROXIMATELY 2 INCHES INBOARD OF WHERE CYLINDER HEAD MEETS BARREL. NO INDICATIONS FROM FLIGHT CREW. A GENERAL NOISE WAS OBSERVED FROM MAINTENANCE PERSONEL DURING A ROUTINE 50 HOUR OIL CHANGE WHICH INCLUDED A DIFFERENTIAL CYLINDER LEAK CHECK.