As aircraft increase in size and required capital investment, the incentives for development and application of techniques and methods for optimizing the availability of the aircraft becomes increasingly attractive. Currently, a family of techniques, which can be broadly defined as engine condition monitoring, are being applied to reduce the downtime assignable to the aircraft power plant. The mechanical health of the engine is assessed through such techniques as parameter monitoring, vibration analysis, oil monitoring, borescope inspection, and radiography to provide problem detection, isolation, and trend monitoring. The effectiveness of a condition monitoring system depends upon the realization of a compatable interface between the basic engine design and installation, and the monitoring system, as well as the application of effective diagnostic logic to the acquired data. The purpose of this paper is to examine the design interface requirements for selected monitoring techniques and the analytical methods for data interpretation, and to recommend the design features needed to enhance the monitoring capabilities to approach the optimum overall condition monitoring system.