The desire and need for real predictive prognostics capabilities have been around for as long as man has operated complex and expensive machinery. There has been a long history of developing and implementing various degrees of prognostic and predictive useful life remaining capabilities. Stringent Diagnostic, Prognostic, and Health Management capability requirements are being placed on many of the new platform applications. While life usage accounting and fault detection / isolation effectiveness, with low false alarm rates, continue to improve on these new applications; prognostics requirements are even more ambitious and present very significant challenges to the system design teams. Though advanced life prediction and prognostic capabilities are being addressed for many mechanical and electronic systems; there are some unique challenges and issues associated with modern propulsion system applications. This paper will explore some of these design challenges and issues; discuss the various degrees of prognostic capabilities; address potential development methodologies; and draw heavily on lessons learned from previous prognostic development efforts.Copyright © 2006 by ASME