PROF-the Probability of Fracture, is a computer program developed by Research Institute, University of Dayton aiming to provide a fleet risk assessment methodology for aging aircraft fleets of United States Air Force (USAF) in the mid 1990. This computer program considers the statistical characteristics of material properties, the usage of aircraft fleets, and, mostly important, the dilemma between the costs for inspection, repair, modification or life extension program vs. requirements of safety operations for those aging aircraft fleets. Current study utilized 125 T-38 training fleet to demonstrate the usage of PROF, and normalized total expected maintenance cost for two inspection methods as a function of inspection interval are calculated to present the effectiveness of this program