The net effect is a positive impact on profitability due to increased revenues [Dunn, 1990], although most authors only evaluate the positive impact of lower maintenance costs on profit [Andrica, 1983;Bleuel, 1981; Kelly, 1980; Kelly and Eastburn, 1982]. Bleuel and Patton [1987] include the concept of revenue when they present maintenance as a support function utilized to achieve the production level required to generate the company’s revenue and profit goals.