On June 17, 1994, at 1155 central daylight time, an Aerospatiale ATR 72-212, N632AS, sustained minor damage while in cruise flight near Caddo, Oklahoma. There were no injuries to the 33 passengers and the 4 crewmembers aboard the airplane. Visual meteorological conditions prevailed for the 14 CFR Part 121 flight. The airplane was operated by Atlantic Southeast Airlines as ASA Flight 7605, on an instrument flight plan between Tulsa, Oklahoma, and DFW International Airport, Texas. According to the operator, the airplane was in cruise flight at 16,000 feet when the fire warning light for the left engine illuminated. The crew activated the onboard fire suppression system and secured the affected engine. The captain advised ATC of the situation and continued inbound to DFW, requesting priority handling. The airplane landed without further incident at 1236, and the passengers were deplaned by normal means. Inspection of the left engine revealed fire damage that was confined to the bottom of the engine cowling. Further inspection revealed evidence of a fuel leak originating at the fuel nozzle drain collector for the left engine. According to the operator, the O-ring (part number MS-9388-009) for the number six fuel nozzle transfer tube was defective. Total time on the defective O-ring was reported as 339 hours.