On January 17, 1995, at 0710 central standard time, an ATR-72-212, N408AT, sustained substantial fire damage while taxiing at the Dallas/Fort Worth (DFW) Airport, Texas. Three crewmembers and 32 passengers were not injured, while one flight attendant and one passenger received minor injuries. The aircraft, owned and operated by Simmons Airlines, operating as American Eagle flight 3500, was on a scheduled Title 14 Part 121 flight from Lubbock, Texas. Visual meteorological conditions prevailed for the flight. According to the operator, the flight departed Lubbock at 0600. The flight crew noted normal departure and normal brakes when they were tested. The flight touched down on Runway 36L at 103 knots with gross weight of 37,700 pounds. According to the flight crew, no brakes were applied during the landing rollout, and in fact, were not used until the aircraft stopped on the taxiway. The flight crew added that a hard deceleration occurred approximately seconds after touchdown. The crew used left rudder and nose wheel steering to maintain the aircraft on the centerline. Propeller reversing was not used. The aircraft exited the runway on taxiway E-2 and was cleared to cross runway 36R and proceed to taxiway G via WK. As the airplane taxied across runway 36R, the hot brake caution light illuminated. The crew reported to the local controller that they needed to stop on the taxiway due to a right gear problem. Fire was reported in the right main gear and an emergency evacuation to the left side of the airplane was initiated by the crew. Post accident inspection of the aircraft revealed that the fire was the result of the uncommanded brake application to the number 3 and 4 tires on the right main landing gear. Fire damage was limited to the area adjacent to the right main landing gear. The fore and aft pressure deck panels and the landing gear bay keel were destroyed by the fire. The right hand landing gear system as well as all the fairings were replaced. The following aircraft components were retained for further evaluation and testing: All brake temperature thermocouples, all brake temperature transmitters, the antiskid control unit and manifold, all four wheel speed transducers, the number 1 and 4 hubcaps, the metering valve, both tires for the right main landing gear (MLG), both main wheel assemblies for the right MLG, and both main brake assemblies for the right MLG. No anomalies were found in any of the systems inspected/tested. A detailed report of each investigation is enclosed.