What was found
PILOT REPORT: COMING BACK IN ON LIFT ARRIVAL, FELT ENGINE SHUDDER FOLLOWED BY DUAL ECU FAILURE. ECU A KEPT COMING ON AND OFF. INTERMITTENT POWER LOSS, HEADING TO 2R2. COMING INTO LAND AT 2R2, HAD LOSS OF OIL PRESSURE. MAINTENANCE FINDINGS: FOUND ROCKER COVER PENITRATED. REMOVED COVER AND FOUND #4 CYLINDER ROCKER BROKEN. PERFORMED BORESCOPE AND FOUND BROKEN VALVE AND DAMAGED PISTON.