What was found
NR 1 ENGINE FIRE DETECT LOOP B WON'T TEST. ACFT GROUNDED. UNABLE TO DUPLICATE DEFECT, SET THE NR 1 ENGINE LOOP SELECT SWITCH TO BOTH AND PERFORMED ENGINE FIRE DETECTION. OPS TESTED IAW AMM 26-11-00-710-801, ALL TESTS PASSED AND M279 ENGINE AND APU FIRE DETECTION CONTROL MODULE SHOWS NO LOOP FAULTS. OPENED THE NR 1 ENGINE COWLING AND PERFORMED GVI OF ENGINE FIRE DETECTION LOOPS, HARNESSES, AND TERMINAL CONNECTIONS, NO DEFECTS NOTED. SHOOK DOWN THE NR 1 ENGINE HARNESS CONNECTIONS WHILE MONITORING M279 MODULE FOR FAULTS, NO FAULTS NOTED. PERFORMED ENGINE FIRE DETECTION OPS TEST IAW AMM 26-11-00-710-801, ALL TESTS PASSED.