As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING ROUTINE ENGINE OIL CHANGE, FUEL STAINS WERE NOTED ON INTAKE MANIFOLD BELOW EACH CYLINDER INTAKE PORT AND BETWEEN THE CYLINDER HEAD FINS IN THIS AREA. PERFORMED DIFFERENTIAL COMPRESSION TEST WITH LOW COMPRESSION NOTED ON NR 1 AND 5 CYLINDERS. SOAP BUBBLE LEAK CHECK REVEALED CRACKS ON BOTH CYLINDER HEADS BETWEEN FINS ABOVE INTAKE PORTS. REMOVED ALL CYLINDERS FOR FURTHER INSPECTION. EACH CYLINDER WAS FOUND TO HAVE CRACKS EMANATING FROM THE TOP SPARK PLUG BOSS TO THE INTAKE VALVE AREA.