As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CLIMBING THROUGH FL 19.0, RECEIVED A NR 3 ENQINE FIRE INDICATION. BOTH A & B LOOP NACELLE TEMPS READ 8.5. STARTED ENGINE FIRE CHECKLIST, BROUGHT NR 3 THRUST LEVER CLOSE. FIRE SWITCH LIGHT EXTINGUISHED. COMPLETED CHECKLIST. DID NOT DISCHARGE FIRE BOTTLE, FOUND PRESSURE RELIEF VALVE FAILED. REPLACED PRESSURE RELIEF VALVE IAW MM. ENGINE RUN ACCOMPLISHED IAW MM AND ALL OPERATED NORMAL. OK FOR SERVICE)