As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING AN INSPECTION, IT WAS NOTICED ON THE TOP COWL BLACK SOOT NEAR CYLINDER NR 5. COMPRESSION TEST DONE AND CYLINDER SPRAYED WITH SOAP SOLUTION. BUBBLES WERE SEEN WHERE THE CYLINDER HEAD AND BARREL ATTACH. CYLINDER REMOVED AND CRACK FOUND. THIS IS CYLINDER WITH 569 HRS ON IT SINCE TSO. AD 2009-26-12 DOES NOT AFFECT THIS PN CYLINDER ASSY BUT YET IT HAS CRACKED IN THE SAME PLACE AS THE AFFECTED CYLINDERS.