Estimating the remaining useful life of critical rotorcraft components has proven difficult, even for platforms with a long service history. An approach has been developed that makes significant technological and practical progress towards enabling design optimization for in-service reliability and remaining useful life estimation with an emphasis on rotorcraft drivetrain components. The approach encompasses a multi-scale physics-based methodology to virtually compute the reliability characteristics of rotorcraft drivetrain components. Several validations of the approach, including with third parties, have been conducted. Furthermore, techniques have been developed such that these types of materials science-based models can be shared among OEMs, suppliers, and operators. These techniques have been successfully implemented to produce a prognostic capability in the wind energy industry.