What was found
ON DESCENT THE CREW ADVANCED THE THROTTLES AND HEARD 3 LOAD BANG SOUNDS FROM THE NR 1 ENGINE. THERE WERE NO ABNORMAL ENGINE INDICATIONS. CREW RETARDED THROTTLES SLIGHTLY AND THE SOUNDS DISSIPATED AND DID NOT RETURN. CREW LANDED IN KOA WITHOUT FURTHER INCIDENT. MAINTENANCE INSPECTED THE NR 1 ENGINE. RAN THE ENGINE FOR AN ACCELERATION CHECK. ENGINE RUN TEST OK. MAINTENANCE ALSO LUBED THE BLEED VALVES AS A PRECAUTION AND RETURNED THE AIRCRAFT TO SERVICE.