What was found
IN DESCENT THROUGH FL200, THE NR 1 FIRE HANDLE LIGHT CAME ON INTERMITTENTLY. IN CONJUNCTION WITH THE FIRE HANDLE AND BELL, THE NR 1 ENGINE DETECTOR INOP LIGHT ILLUMINATED. RAN QRH FOR ENGINE FIRE AND SHUT THE NR 1 ENGINE DOWN. INSTALLED A NEW FIRE CONTROL UNIT PER AMM 26-11-000-4. TESTED PER AMM 26-11-000-1, OPS CHECK GOOD. INSTALLED A NEW MAIN OIL FILTER, NO METAL FOUND IN THE OLD FILTER. RAN THE ENGINE PER B-727-200 JRH, OPS AND LEAK CHECK GOOD.