During November 2025, Jaehoon Choi delivered a rotor subassembly redesign for turbopump shaft components in the PURPL-Purdue/Turbopump repository. The work consolidated the rotor shaft, bearing components, and introduced a modular face shaft split, aiming to improve performance, reliability, and maintainability. Using CAD modeling and mechanical design skills, Jaehoon focused on reducing assembly time and simplifying maintenance by clarifying interfaces between shaft components. The modular approach established a foundation for future upgrades and potential field-service efficiency gains. All changes were managed through disciplined, Git-driven commits, demonstrating a methodical engineering process and proficiency in assembly design and engineering design within a complex system.