What was found
BNA - FLT 0691 - DURING CLIMB-OUT AT 18,000 FEET, TAIL COMPARTMENT HIGH TEMPERATURE LIGHT ILLUMINATED. CREW FOLLOWED CHECK LIST AND TAIL COMPARTMENT HIGH TEMPERATURE LIGHT EXTINGUISHED. AIRCRAFT AIR INTERRRUPTED AND RETURNED TO BNA WITHOUT FURTHER INCIDENT. REPLACED BROKEN COALESCER ASSEMBLY COUPLING AND AS A PRECAUTIONARY, REPLACED WATER SEPARATOR BAG. RAN ENGINES AND PACKS WITH NO LEAKS DETECTED AND TAIL COMPARTMENT HIGH TEMPERATURE LIGHT DID NOT ILLUMINATE. SYSTEM GROUND CHECKED, NORMAL OPERATION. (X)