Modeling CT7/T700 Maintenance Costs

Turboshaft engines are a significant contributor to rotary wing aircraft life cycle costs, typically over 40%. Maintenance costs are the largest portion of the life cycle cost of an engine, as compared to development, acquisition, and fuel costs. Understanding these costs is important to guiding engine design and maintenance practice decisions. This paper describes the development and use of deterministic and probabilistic simulation model of the CT7 commercial turboshaft engine and its application to US Army maintenance of a military version of the engine. The model is used on several commercial aircraft to quantify engine maintenance costs ($/EFH), time on wing (TOW), field maintenance labor hours, and required sparing. The application of this model to the US Army T700-GE-701D engine is described. Maintenance practices are analyzed to optimize readiness at best value. Engine design tradeoffs are evaluated based on overall Life Cycle Cost. The influence of operating environments is also addressed, such as accounting for the impact of harsh environments. Recommendations to reduce maintenance cost per hour are described.