Maintainability Derivations Using the Analytical Maintenance Model

The application of the analytical maintenance model to the analysis of the launch readiness of systems is described, and the maintainability contribution to the system operational readiness is also derived. Where the probability of multiple malfunctions during a time-limited operational sequence is significant, the specification of maintenance capability can become involved. A simplifying process using the gamma distribution is described which expresses the maintenance capability in terms of a probability of performing the restore function within a time limitation. Similarities between the empirical distribution and the gamma distribution are discussed. These similarities are worthy of note by way of introducing the gamma distribution as a useful descriptor of downtime frequencies of occurrence. The distributions most commonly used are the log normal and the negative exponential. The reason for considering the gamma distribution as a potential alternate is its relative algebraic simplicity. The rationale for this approach is described. The potential usefulness of the procedures developed will apply to maintainability prediction, assessment, and validation, and further to system or subsystem levels.