What was found
NR 1 ENGINE FIRE DETECTION LIGHT IS INOPERATIVE. ACFT GROUNDED. UNABLE TO DUPLICATE DISCREPANCY. ACCOMPLISHED GENERAL VISUAL INSPECTION OF THE NR 1 ENGINE FAN AND CORE FIRE DETECTOR ASSEMBLY AND HARNESS. NO DEFECTS NOTED. PERFORMED NR 1 ENGINE FIRE DETECTION LOOP RESISTANCE SYSTEM TEST IAW AMM 26-11-00-730-801. ALL RESISTANCE VALUES WITHIN LIMITS. PERFORMED ENGINE AND APU FIRE DETECTION OPERATIONAL TEST IAW AMM 26-11-00-710-801 AND 26-15-00-710-801. TEST PASSED WITH NO FAULTS. OVERHEAT DETECTOR SWITCH PLACED IN NORMAL POSITION.