What was found
MCI - FLT 1159 - DURING CLIMB, RT ENGINE 'B' FIREWARNING LOOP FLICKERED ON, SWITCHED TO 'A' LOOP. AFTER LEVEL-OFF AT CRUISE, 'A' LOOP WARNING CAME ON AND WENT OFF. FOUND LOWER APRON 'A' AND 'B' LOOPS CHAFED. REPLACED 'A' AND 'B' APRON LOOPS, MFG PN 5938323-505 AND PN 5938323-506, AND FIREWARNING SYSTEM OPERATION CHECKED NORMAL. CHECK C-2D - 11-15-95 - MCI. REFERENCE: OPERATOR CONTROL NR 96ZZZX1193.