Modeling, Analysis, and Optimization of Rotorcraft and Fleet Availability

The availability of a rotorcraft fleet to fulfill missions is driven by the size of the fleet, time-varying mission demand profile, average mission duration, inspection and maintenance times as well as other factors impacting the logistics and supply chain. Traditional availability measures such as the steady state availability and transient availability lack the expressivity needed to determine the probability that a specified fleet size and supporting maintenance staff will be able to ensure a mission can be initiated at a specified point in time given an anticipated mission profile. In the absence of sufficiently robust modeling and analysis techniques, it is also difficult to determine how rotorcraft reliability and maintenance process improvements could be implemented to enhance traditional and extended notions of rotorcraft and fleet availability. This paper presents methods to model and assess the impact of subsystem reliability investment on rotorcraft availability. We also extend traditional availability concepts to the case of on-demand availability, where availability is characterized as a time-varying function of the demand for a fleet of rotorcraft. The examples illustrate that the approach can be used to consider tradeoffs between on-demand availability and factors such as fleet size and maintenance times.