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This paper presents a model for optimal asset maintenance inspection services. The model is designed to support through-life service in the form of multiple nested inspections and maintenance to meet defined asset availability and capability requirements, as well as achieving successful through-life technology insertions. The inspections and maintenance activities are assumed to be performed at more than one level, but nested and aimed at different types of defects or subsystems over a fixed period of time (the designed asset life). This practice is common in many industries, particularly in the defense industry. The impact of technological insertions is reflected through changes in the failure behavior of the asset. We use the delay time concept to model the failure mechanism of the asset, and the arrivals of defects are assumed to follow Poisson processes. The decision variables are the inspection intervals, while the objective function can be expressed in terms of cost, downtime, or reliability. The model is demonstrated through a numerical example. The model can be used for optimizing two-level inspection intervals with technological insertions.