As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE OIL CHANGE AND DIFFERENTIAL CYLINDER LEAK CHECK, NR 3 CYLINDER FAILED AND A HISSING NOISE WAS OBSERVED. A CRACK WAS DISCOVERED APPROXIMATELY TWO INCHES INBOARD OF BARREL HEAD JOINT ON AFT SIDE OF CYLINDER AT APPROXIMATELY THE 9 O'CLOCK POSITION.