On January 21, 1997, at 2245 central standard time, a Boeing 727-100, N198FE, registered to and operated by Federal Express Corporation as Flight 1272 on a Title 14 CFR Part 121 domestic cargo flight, experienced the activation of the fire warning light in the cockpit during the departure climb to cruise from the Will Rogers World Airport, Oklahoma City, Oklahoma. The flight was on an IFR flight plan with a final destination of Memphis, Tennessee. Visual meteorological conditions prevailed. The airplane was not damaged and the 3 flightcrew members and a company pilot on the cockpit jumpseat were not injured. The flight returned to Oklahoma City and landed without further incident. During personal interviews, conducted by the investigator-in-charge (IIC), and on the enclosed statements, the flight crew reported that during the initial climb, between 4,000 feet and 4,500 feet MSL, the crew received an aural warning and the number 2 smoke detector sensor (located for detection in cargo bins 4 and 5) light illuminated in the cockpit. The captain of Flight 1272 requested that the company pilot on the jumpseat open the cockpit door and check for smoke in the cargo areas. Upon opening the door, the crew members noted a "strong smell like lacquer and varnish." The captain declared an emergency and subsequently requested and received an ATC clearance for a visual approach and landing at the airport. The flight landed on runway 17L, exited at taxiway Echo, and stopped on the taxiway. The crew deployed the emergency slide and everyone exited the airplane. At the local hospital, all flight personnel were checked for fume inhalation and released. Local authorities, FAA inspectors and company personnel examined the aircraft cargo and reported to the IIC that no evidence of an in flight fire or hazardous cargo spill was found in the hazardous cargo container at position 1 or the other cargo containers. The cargo container at position 5 is located between station 695.45 and 784.45 on the Boeing 727-100. The cargo container at position 5 contained 3 boxes of furniture panels that emitted fumes. Two of the boxes were 4 feet by 2 feet by 6 inches and one box was 2 feet by 1 foot by 3 inches. During telephone interviews, conducted by the investigator-in-charge, personnel of Winslow and Associates at Oklahoma City, Oklahoma, a furniture company, reported that a store in Tampa, Florida, was being finished for a grand opening and called Winslow and Associates for additional furniture panels. Winslow and Associates has an agreement for shipping the panels via Federal Express. The panels were painted during the day with a base coat (Kem-Flash E61A45) and a topcoat (Production Lacquer L61XX Lead-Free Custom) and dried for approximately 7 hours. At approximately 1830, the 3/4 inch thick wood panels, dried to touch, were crated. Subsequently, at 1930, they were taken to the Federal Express ramp at the airport. The Federal Express ramp agent, who loaded the boxes into the cargo container at approximately 2130, did not notice any smell or fumes when the container was loaded into cargo bin number 5. Ramp personnel further stated that the temperature was about 40 degrees Fahrenheit. Personnel of the furniture company (Winslow and Associates) stated that the panels cure for several hours after they have been painted and the painted panels may emit a paint like odor during the curing process; however, the fumes are nonflammable. The paint shop environment tested at 5 parts per million (toluene and/or other hydrocarbons) with the specification limit at 100 ppm. The paint mixing room containing 5,000 gallons of paint/lacquer does not reach the 100 ppm limitation. Following the incident, the furniture boxes were off loaded. Maintenance personnel replaced a cargo net and the crew emergency slide. The aircraft was returned to service and the crew taxied for the departure flight. During the takeoff roll, the #2 sensor illuminated and the crew aborted the takeoff. Maintenance personnel replaced the #2 sensor and the airplane was dispatched for flight the following morning. The FAA Southwest Regional Hazardous Material Coordinator stated that once the paint had been used on the panels, it was not considered a hazardous material, even though the paint was still in a curing stage. The fumes responsible for the paint odor are considered non flammable. The smoke detector, Part No. 7740-01, Serial No. 2024, operates based on the percentage of light transmitted (particle density). The unit was tested within the manufacturer's specifications by Whittaker Safety Systems at Simi Valley, California.