As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CRUISE FROM KTOL THE FIRE WARNING LIGHT AND BELL CAME ON FOR THE NR 4 ENGINE. NO OTHER INDICATIONS WERE NOTED. CREW RETURNED AIRCRAFT TO KTOL AND LANDED WITHOUT INCIDENT. AN INSPECTION IS ON GOING. AS SOON AS THE INFORMATION IS AVAILABLE IT WILL BE PROVIDED. MAINTENANCE OHM CHECKED FIRE WARNING SYSTEM, FINDING INTERMITTENT PROBLEM. REMOVED AND REPLACED 5 FIRE SENSING ELEMENTS, CHECKED BLEED LINES FOR LEAKS WITH NONE NOTED. RAN AIRCRAFT TO POWER AND FIRE WARNING CHECKED GOOD PER ALL APPLICABLE MANUALS. AIRCRAFT WAS RETURNED TO SERVICE.