What was found
(CAN) ON LANDING, THE OIL PRESSURE ON THE LT ENGINE DROPPED TO 35 PSI WHEN THROTTLE AT IDLE. INSPECTION SHOWED OIL FROM BREATHER TUBE ON THE AIRFRAME. COMPRESSION CHECK IDENTIFIED THE NR 3 CYLINDER AT 0/80. CYLINDER REMOVED AND PISTON FOUND DAMAGED AT 2ND RING GROOVE ALLOWING, BLOW BY. APPEARS THAT THE END OF THE RING, APPROXIMATELY .2500" HAD BROKEN OFF AND DAMAGED THE PISTON BY FRETTING. RING, PN 74241. ENGINE O/H 22 OCT. 2006. PISTONS AND CYLINDERS NEW AT THAT TIME.