What was found
UPON ROTATION NR 1 ENGINE FIRE WARNING WENT OFF. COMPLETED APPROPRIATE CHECKLIST. DUE TO BEING ON 3 ENGINE FERRY, WAS NOW ON 2 ENGINES. DECLARED EMERGENCY, RETURNED TO HUF. TROUBLESHOT, FOUND NO FIRE BUT INDICATION ONLY. FOUND WIRE PULLED FROM AFT OUTBOARD COWL CANNON PLUG. INSTALLED NEW PIN, GROUND TEST SEVERAL TIMES, OK FOR SERVICE IAW MM 26-2-0. (M)