What was found
THE NR 1 ENGINE OIL PRESSURE BEGAN TO DECREASE AND WAS ACCOMPANIED BY ILLUMINATION OF THE NR 1 ENGINE LOW OIL PRESSURE LIGHT WHILE EN ROUTE. THE ENGINE WAS SHUTDOWN AS A PRECAUTIONARY MEASURE AND THE AIRCRAFT WAS RETURNED TO EWR WHERE IT LANDED WITHOUT INCIDENT. THE NR 1 ENGINE WAS REMOVED AND REPLACED. THE SDR WILL REMAIN OPEN FOR PART INFORMATION PENDING INVESTIGATION. *S/D* THE GEARBOX WAS REMOVED AND REPLACED ON LINE. SHOP FINDINGS REPORTED NO TROUBLE FOUND DURING ENGINE TEST CELL RUN.