What was found
(CAN) LOW OIL PRESSURE INDICATION IN FLT ON LT, NR 1 ENGINE. PILOT SHUT DOWN NR 1 ENGINE AND CONDUCTED EMERGENCY LANDING. INITIAL VISUAL INSPECTION SHOWED OIL HAD SPEWED OVER COWLING. FURTHER INVESTIGATION LATER SHOWED EVIDENCE OF EXCESSIVE HIGH ENGINE GEARBOX PRESSURE AS INDICATED BY OIL FILTER HOUSING BEING PULLED OUT OF GEARBOX. ENGINE WAS INSPECTED PREVIOUSLY FOR INTERMITTENT OIL LOSS BETWEEN FLIGHTS. AT ONE TIME 4 QUARTS WERE LOST IN ONE 3 HOUR LEG. INVESTIGATION AT THAT TIME PRESUMED POSSIBLE LOSS OF OIL FROM ALTERNATOR AND STARTER GEN PAD SEALS. SEALS WERE REPLACED. ENGINE REMOVED FOR INVESTIGATION AND REPAIR. LOANER ENGINE INSTALLED AND AIRCRAFT RETURNED TO SERVICE.