What was found
DURING PRE-START CHECKLIST FOR APU -FOUND LOOP "B" FOR NR 2 ENG FIRE DETECT INOP. (NO ILLUMINATION IN NR 2 FIRE HANDLE). GROUNDED - YES. ENGINE FIRE DETECTION OPERATIONAL TEST DONE SUCCESSFULLY MULTIPLE TIMES REF AMM 26-11-00-710-801. NO FAULTS AND NR 2 ENG HANDLE LIGHTS UP EVERY TIME. GVI DONE ON ALL NR 2 FIRE DETECTION HARNESSES: TERMINALS ALL SECURE AND NO VISIBLE DAMAGE TO DETECTORS. NO HISTORY PAST 30 DAYS. THIS CLEARS MEL 26-2B. OVHT DET SWITCH FOR NR 2 ENG PLACED BACK IN NORMAL POSITION AND ALL PLACARDS REMOVED.