What was found
NR 2 ENGINE LOOP "B" FAULT DURING CRUISE AT FL 300. EXTINGUISHED DURING DESCENT. CREW DEBRIEF INDICATED THAT B LOOP LIGHT NEVER ACTUALLY CAME ON JUST FLICKERED. HAS HISTORY, PERFORMED ENG FIRE TEST REF AMM 26-12-05, TEST GOOD, BITE TEST OF FDCU NO FAULTS. RAN OUT OF TIME. RELEASED FOR SERVICE PER MEL: 26-12-XXXXX CAT C ENG 2 LOOP B INOP. FLIGHT CREW MUST PERFORM FUNCTIONAL TEST OF ENG FIRE WARNING SYSTEM PRIOR TO EACH DEPARTURE. PERFORMED OP'S TEST IAW AMM 26-12-00-05-01. OP'S CHECKED GOOD SEVERAL TIME. OK FOR SERVICE. CLEARED MEL.