The reliability and maintainability (R&M) model described in this report represents an important portion of a larger effort called the Digital Avionics Information System (DAIS) Life Cycle Cost (LCC) Study. The R&M model is the first of three models that comprise a modeling system for use in LCC analysis of avionics systems. The total system will provide the Air Force with an enhanced in-house capability to incorporate LCC considerations early in the system acquisition process. As part of the overall modeling system, the R&M model provides estimates of failure rates, maintenance manpower requirements, support equipment requirements, and spares requirements which are used to generate estimates of system support costs. When operated in a stand-alone mode, the R&M model can be utilized to analyze the impact of various avionics design configurations on system support requirements. This report describes the R&M model in detail. The technical approach is discussed in general and then specific terms. Particular attention is given to the analysis that led to the model specification and to the model's functional description in terms of input, output, and process. A specific example calculation is given to illustrate how the model can be utilized to conduct an R&M study. (Author)