What was found
LGA - FLT 2990 - ON CLIMB-OUT FROM LGA, AFTER FL120, CREW REPORTED LOSS OF NR 1 ENGINE OIL AND THE LOW OIL PRESSURE LIGHT ILLUMINATING. OIL PRESSURE DROPPED BELOW THE RED LINE AND HELD AT ABOUT 20 PSI. CREW SHUT DOWN THE NR 1 ENGINE, DECLARED AN EMERGENCY AND RETURNED TO FIELD AT LGA. FLIGHT LANDED WITHOUT FURTHER INCIDENT. TOTAL SINGLE ENGINE TIME WAS 8 MINUTES. MAINTENANCE REMOVED AND REPLACED THE NR 1 ENGINE ASSEMBLY. OPS CHECK AND LEAK CHECK GOOD. (M)