ENG. FIRE WARNING : THE FDU. GENERATES A FIRE WARNING SIGNAL IF ANY OF THE FOLLOWING CONDITIONS ARE MET1. FIRE ON LOOP-A AND LOOP-B2. FIRE ON LOOP-A AND FAULT ON LOOP-B3. FAULT ON LOOP-A AND FIRE ON LOOP-B4. FAULT BOTH-LOOP WITHIN 5 SECONDS ( BOTH LOOP BROKEN DUE TO A TORCHING FLAME )