What was found
ON 24 MAR 04, AC DEPARTED, AT APPROX 50 MILES FROM DEPARTURE, PILOT NOTICED A LOSS OF MANIFOLD PRESSURE AND A LOSS OF OIL PRESSURE ON THE LT ENGINE, FEATHERED THE LT PROPELLER, SHUT DOWN THE LT ENGINE AND RETURNED TO DEPARTURE. A MAINTENANCE INSPECTION REVEALED THAT THE LT OIL COOLER HAD RUPTURED, LEAKING OIL FREELY. MAINT HAS ELECTED TO REPLACE THIS ENGINE.