What was found
AFTER TAKEOFF WITH STANDARD POWER SET, NR 3 ENGINE FIRE WARNING ALARM. ENGINE WAS SHUTDOWN IAW QRH FIRE LIGHT WENT OUT WITH START LEVER TO CUT OFF. GOOD FIRE WARNING TEST. FOUND SEVERED TUBING COMING TO FUEL HEATER S/O VALVE INLET PORT. ALSO FOUND GROUNDING WIRES SEVERED JUST BENEATH THE SEVERED TUBING. REPLACED FUEL HEATER S/O VALVE INLET TUBE, RAN ENGINE IAW JRH. ACCOMPLISHED FUEL HEATER CHECK IAW AMM 73-14-000-5. ALL OK. NO LEAKS NOTED. REPLACED SEVERED GROUNDING WIRING IAW STD PRACTICES MANUAL 20-10-13.