This Principal Mechanical Engineer role serves as a technical lead within TransMedics' sustaining engineering team, driving innovation across the company's on-market product portfolio. Key responsibilities include leading end-to-end mechanical design development, conducting advanced structural and thermal analyses, and chairing program-level design reviews. The position also involves defining test methodologies, managing engineering change orders, and collaborating with manufacturing partners to ensure design for manufacturability. The role appeals to candidates seeking to impact patient lives by expanding access to viable donor organs in a mission-driven environment. While the position is based in the Boston area with potential relocation to Somerville by 2028, it offers opportunities for professional growth, cross-functional collaboration, and the chance to shape engineering standards in a high-impact medical technology setting.