What was found
(CAN) DURING 200 HR INSP OIL FOUND BETWEEN NR 1 & 3 CYLINDERS. COMPRESSION CHECK CARRIED OUT TO DETERMINE CYLINDER THAT PRODUCING OIL. BOTH CYLINDERS PRODUCED NORMAL COMPRESSION READINGS. WHEN BOTTOM SPARK PLUGS WERE REMVD ONE FROM CYLINDER NR 3 FOUND TO HAVE EVIDENCE ON BURNED OIL. NR 3 CYLINDER ASSY & PISTON REMVD. PISTON HEAD COVERED IN BURNED OIL RESIDUE. PISTON HEAD HAD ALSO HAD SMALL PORTIONS OF ITS SURFACE CHIPPED AWAY. DURING THE PREVIOUS INSP (50 HR) NR 1 CYLINDER ASSY & PISTON WERE REPL. IT BELIEVED THAT FAILURE OF NR 1 PISTON RESULTED FROM FAILURE OF PISTON RING.