As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
(CAN) AT THE 50 HRS INSPECTION OF THE AIRCRAFT, DURING ENGINE CYLINDER COMPRESSION TEST, MADE ENGINE SB M91-6, AND THE TEST FAILED BECAUSE FOUND AIR LEAK AT THE JUNCTION OF THE CYLINDER BARREL AND THE TOP CYLINDER HEAD (BETWEEN FINS). THE ENGINE AND CYLINDER HAD ONLY 90.5 HRS. REPLACED CYLINDER AND RETURNED AIRCRAFT TO SERVICE AFTER THE INSPECTION.