What was found
SOP/CLT - FLT 5117 - ON INBOUND FLIGHT, THE NR 2 ENGINE OIL PRESSURE DROPPED TO ZERO AND OIL LIGHT ILLUMINATED. IN-FLIGHT EMERGENCY WAS DECLARED. ENGINE WAS SHUT DOWN IN-FLIGHT. AIRCRAFT MADE A SAFE ONE-ENGINE LANDING IN CHARLOTTE. MAINTENANCE DISPATCHED TO ACFT AND FOUND LOOSE B-NUT ON NR 2 ENGINE OIL COOLER. RETORQUED B-NUT, SERVICED ENGINE, RUN AND OPS CHECKED GOOD. AIRCRAFT RETURNED TO SERVICE. (X)