Model to Determine the Economic Life of Air Force Motor Vehicles

摘要

The purpose of this thesis was to develop a model to determine optimum service lives for Air Force motor vehicles. The scope was limited to the model's feasibility on one type of vehicle. The vehicle selected was the 4K electric forklift, National Stock Number 3930-00-053-9175. The sample consisted of 158 vehicles out of a population of 742. Operations and maintenance data were extracted from VIMS reports from four Air Force Logistics Command installations. Age was not distributed normally; only 6 of the 158 vehicles were more than 12 years old. Linear regression was used to develop a maintenance cost function with age as the independent variable. The function was not linear, and heteroscedasticity was present. A weighting technique was applied to correct for heteroscedasticity, and the model was transformed to account for the curvilinear relationship. An amortized acquisition cost function was also obtained by linear regression. Depreciation was derived from the amount maintenance hour per operational hour increased as the vehicles aged. The total cost curve was found by summing the amortized acquisition and the maintenance cost functions. The economic service life was found to be 14 years; however, given the distribution of the sample, the results were not considered conclusive enough to dispute the current 15 year service life. The overall utility of the model was demonstrated - with limitations. Data requirements would preclude its use for some types of vehicles, but it could prove useful for many others. The author recommended incorporating the model in a VIMS upgrade with the admonition that it be used only where appropriate, and in conjunction with other management indicators. Theses.