On July 29, 2008, at 1021 Alaska daylight time, the flight crew of a Saab-Scania SAAB 340B airplane, N364PX, aborted the takeoff roll from runway 07R at the Ted Stevens Anchorage International Airport, Anchorage, Alaska, after hearing a "pop" come from the left engine. Peninsula Airways, Inc. operated the airplane under Title 14 Code of Federal Regulations Part 121, as PenAir Flight KS221, a regularly scheduled passenger flight. The airline transport certificated captain, the commercial certificated first officer, 1 flight attendant, and 6 passengers were not injured. Visual meteorological conditions prevailed for the flight to the Aniak Airport, Aniak, Alaska. According to the Director of Operations, the flight crew heard a "pop" prior to rotation and aborted the takeoff. The flight crew noted a momentary over-temperature light, and the captain shut down the left engine. Prior to removal, PenAir maintenance personnel reported that the damage remained contained within the left engine. GE Aviation inspected the engine and reported that one of the stage 1 gas generator rotor blades (part number 5088T43P05) had separated below the airfoil platform. GE Aviation further reported that the blade separated due to high-cycle fatigue, which is related to blade damper binding issue that they have been tracking since 2001. A service bulletin (SB) has been issued (SB 72-0475) to address the gas generator rotor blade damper, and GE Aviation reports on the status quarterly to the Federal Aviation Administration. In part, the SB introduces a blade damper that is not as susceptible to binding. GE Aviation has recommended to the operators that have not complied with the SB to lower the interval of the borescope inspection (BSI) for the "hot" section from 800 flight hours to 400 flight hours between inspections, to identify this issue prior to a blade separation. To date 95-percent of the fleet has complied with the service bulletin. This engine was not in compliance with SB 72-0475 at the time of incident.