What was found
ALB - FLT 291 - DESCENDING THROUGH 10,000 FEET AT IDLE POWER, CREW NOTICED THE LOW OIL PRESSURE LIGHT FOR THE NR 1 ENGINE ILLUMINATED. THEY CONFIRMED LOW OIL PRESSURE LIGHT WITH QUANTITY GAUGE AND OIL PRESSURE GAUGE. AT THAT TIME, CREW SHUT DOWN THE NR 1 ENGINE IN-FLIGHT AND DECLARED AN EMERGENCY. FLIGHT LANDED WITHOUT FURTHER INCIDENT. TOTAL SINGLE ENGINE TIME WAS 10 MINUTES. AT SHUT-DOWN, OIL PRESSURE WAS LESS THAN 10 PSI. MAINTENANCE FOUND THE NR 1 ENGINE'S MAIN OIL FILTER O-RING HAD BLOWN. REPLACED FILTER AND O-RINGS. CHECKED CHIP DETECTORS FOR CONTAMINATION. NONE FOUND. SERVICED ENGINE WITH OIL AND RAN ENGINE. NO LEAKS NOTED. SUBSEQUENTLY, THE NR 1 ENGINE WAS REPLACED THE NEXT DAY. (X)