What was found
DURING A FIRE WARNING TEST, THE NR 1 ENGINE B LOOP WAS FOUND INOPERATIVE. ACFT GROUNDED. UNABLE TO DUPLICATE THE DEFECT, NR 1 ENGINE FIRE DETECTION TEST PASSED WITH LOOP SELECTOR ON NORMAL, VISUALLY INSPECTED ALL LOOP TERMINALS FOR SECURITY AND TERMINATION, NO DEFECTS FOUND. DUE TO HISTORY, REMOVED AND REPLACED THE RIGHT CORE FIRE DETECTOR IAW AMM 26-11-01, OPS CHECKED NORMAL.