Reliability, maintainability and testability are at the core of supportability engineering. It is obvious from the descriptions provided in this Chapter that these specialty engineering disciplines play a leading role in achieving any system availability requirement. This point will be confirmed in the discussions at Chapter 9, Availability. The FMECA is an analysis technique that draws all these aspects into a single focus during the systems engineering process. While a FMECA does not guarantee a good design, it provides the vision to make any design better. The reliability, maintainability, testability and FMECA techniques presented in this chapter are based on sound engineering practices and must be applied on every program. They form the basis for many of the topics discussed in subsequent chapters in this book and represent the basic concepts that lead eventually to a supportable system.