Aircraft structures may sustain damage during service operations, and this problem is more acute with rotorcraft dynamic components because of their constant exposure to damaging environments and increased frequency of incidents. Having a quick and reliable fatigue damage evaluation method to assess repair work done in service on dynamic components would be useful, especially if it accounts for effects of static and dynamic response of the component for a given loading exposure, and investigates the impact on fatigue life. To address this, IAI and collaborators will develop REASSESS, an innovative, analytical tool for repair assessment and remaining useful life analysis of rotorcraft dynamic components. The tool leverages a proven method for capturing and measuring multi-axial stresses in a component and combines it with a novel technique to conduct frequency domain finite element analysis. The method more robustly estimates the fatigue and remaining useful life by extending the concept of critical plane to account for both multi-axial stress state and component material properties. The method has been successfully applied by the IAI team to a variety of cases in government and industry. Since the underlying techniques and methods used in REASSESS are agnostic to the type of component being analyzed, it can be used in several applications. The techniques can be included in a commercial software package for use in industrial applications to estimate the life of safety critical structures and components. This tool can be used on heavy-use and highly dynamic components and platforms, including fixed-wing aircraft, automobiles, locomotives, and mining equipment. Further, the modular nature of REASSESS will enable a quick transition to applications in the Navy and in commercial domains.