As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FLT 3663 - RIGHT FIRE DETECTOR FAIL LIGHT CAME ON IN FLIGHT, AIR TURN BACK TO DFW. LANDED SAFELY. INSPECTED WIRING AND ENGINE COMPARTMENT, WAS UNABLE TO DUPLICATED DISCREPANCY. REMOVED AND REPLACED ALL 3 FIRE SENSOR LOOPS ON RIGHT ENGINE AS PRECAUTIONARY MEASURE. OPERATIONAL CHECK GOOD. FUNCTIONAL CHECK FLIGHT PERFORMED SUCCESSFULL. A/C RETURNED TO SERVICE. (M)