What was found
(CAN) ALL 4 CYLINDERS HAVE CRACKS THAT BEGIN AT THE INNER MOST EXHAUST FLANGE STUD AND MOVING TO THE EXHAUST VALVE SEAT, THEN 180 DEGREES ACROSS THE EXHAUST VALVE SEAT TO THE UPPER SPARK PLUG HOLE. SN. E36-10511 E36-10244 E36-10426 E36-10496 NOTE: THIS MAKES 10 OF THESE CYLINDERS FROM 3 DIFFERENT AIRCRAFT IN 6 WEEKS TO HAVE THE SAME CRACKS. TIME ON THESE VARY FROM 1600 TO 2100 HOURS. ALL ON AN (ON CONDITION PROGRAM) REQUIRING AN EXTERNAL SOAPY/WATER LEAK CHECK AND BORESCOPE INSPECTION WHICH IS HOW THE DEFECT IS DISCOVERED. A CYLINDER DPI DOES NOT REVEAL AND A PARTIAL ENGINE TEARDOWN ID REQUIRED FOR VISUAL DETECTION. (TC NR 20060804008)