What was found
NON-ETOPS FLIGHT 82 HNL - KOA - AFTER TAKEOFF, THE CREW WAS ADVISED BY ATC THAT THERE WAS DARK SMOKE TRAILING THE NR 2 ENGINE. CREW NOTED THE OIL QUANTITY DROPPING AND RETARDED THE NR 2 THROTTLE TO IDLE. AIRCRAFT RETURNED TO HNL WITHOUT FURTHER INCIDENT. MAINTENANCE FOUND THE NR 2 OIL CAP LOOSE AND SERVICED THE ENGINE OIL. MAINTENANCE RAN THE NR 2 ENGINE AND FOUND NO OIL LEAKS. AIRCRAFT WAS RETURNED TO SERVICE.