As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
AIR TURN BACK. DURING CLIMB AT APPROX FL 230, NR 3 ENGINE FIRE HANDLE ILLUMINATED. ACCOMPLISHED FHB ENGINE FIRE PROCEDURES. LIGHT EXTINGUISHED AFTER THRUST LEVER SET TO IDLE. INCREASE IN NACELLE TEMP INSPECTION CARRIED OUT IAW AMM. FOUND PRESSURE RELIEF AT FAULT. REMOVED AND REPLACED VALVE OPS CHECKED AND LEAK CHECKED OK. (K)