The maturing air transportation industry is finding profitability to be increasingly elusive. The cost of maintaining aircraft has a substantial impact on profitability. It is incumbent on aircraft and system designers to minimize the cost of maintaining those aircraft to maximize profitability. Choosing mature components and systems that have demonstrated reliability, are familiar to maintenance personnel, and for which spare inventory exists, is an effective technique for minimizing maintenance costs of a new aircraft. This paper discusses examples of such applications and describes the values that can result.