What was found
AT 25000 FT, DURING CRUISE, THE FIRE BELL CAME ON . NO OTHER FIRE INDICATIONS VISIBLE ALL ENGINE INDICATIONS WERE NORMAL EXCEPT NR 2 FUEL TEMP SHOWED +99 DEGREES. IAW THE ABNORMAL FUEL TEMP CHECK LIST, TURNED ON THE NR 2 FUEL BOOST PUMP, NR 2 FUEL TEMP CAME BACK DOWN TO THE NORMAL RANGE BUT WOULD CLIMB BACK TO 71 DEGREES SHORTLY AFTER TURNING THE NR 2 BOOST PUMP OFF. REMOVED FROM SERVICE. REMOVED AND REPLACED THE NR 2 ENG FUEL HEATER THERMAL ACTUATOR IAW AMM TASK 73-11-05-000/400-801, LEAK CHECKED GOOD. RETURNED TO SERVICE.