On August 11, 1997, at 1908 central daylight time, a Saab 340B airplane, N313AE, experienced an engine fire on the left engine while taxiing to the ramp at the Lafayette Regional Airport, near Lafayette, Louisiana. The airplane, owned and operated by Wings West Airlines as American Eagle Flight 5153 was on an instrument flight plan between the DFW International Airport, Texas, and the Lafayette Regional Airport. The two airline transport rated flight crewmembers, the flight attendant, and the 32 passengers were not injured. Damage to the airplane was minor. Visual meteorological conditions prevailed for the Title 14 CFR Part 121 flight. According to the operator, the airplane had cleared the active runway and was taxiing to the ramp near Taxiways B and J, when the flight attendant notified the flight crew that a passenger observed signs of fire coming from the number 1 (left) engine. The captain secured both engines, stopped the airplane, notified the ground control of the fire and ordered a precautionary ground evacuation on the taxiway. The airport rescue and fire fighting equipment and personnel responded to the fire within two minutes. There were no reported warnings or indications of fire in the cockpit. The passengers and crew deplaned the airplane through the normal exits without further incident. Examination of the engine by the FAA inspector revealed that the fire was confined to the internal components of the AC generator located on the top right side of the engine. Damage was limited to the generator and the generator screen in the exhaust port for the AC generator. The operator reported that the engine was undamaged. Total time on the airframe was 10,364.3 hours and 11,957 cycles. The operator reported that the AC generator (part number 31342-001, serial number 1391) had accumulated a total of 9,290.3 hours and 10,747 cycles since new. The time since the last overhaul and installation was 1,097.1 hours and 1,596 cycles. The failed generator was shipped to the manufacturer for further examination and evaluation. A detailed examination of the generator revealed that the anti-drive end bearing failed resulting in subsequent rubbing and heating. The extend of the damage incurred by the bearing and other related parts precluded the manufacturer from determining the cause of the bearing failure.