Lead Mechanical Engineer, Airframe

ABOUT POSEIDON AEROSPACE: Poseidon Aerospace is reimagining how the world moves goods. We build and operate full-size autonomous cargo aircraft - capable of carrying two tons of payload over a thousand nautical miles. From remote communities to contested logistics operations, our platforms unlock a new cost curve for air freight, making it faster, cheaper, and accessible anywhere it's needed. Headquartered in the San Francisco Bay Area with locations in Washington DC, Oregon, and Maine; we're building something consequential. ABOUT THE ROLE The Lead Mechanical Engineer will own the structural and mechanical design of major aircraft assemblies from concept through flight testing. This role is responsible for setting technical direction, leading design reviews, managing subsystem interfaces, and supporting other mechanical engineers. It is a hands-on engineering position that requires detailed involvement in CAD, analysis, manufacturing, assembly, and testing. RESPONSIBILITIES - Lead the design of primary aircraft structures, mechanisms, and major airframe assemblies - Develop composite and metallic structures, joints, interfaces, and mounting systems - Define structural load paths, design requirements, margins, and validation methods - Perform and review hand calculations and finite element analysis - Evaluate strength, stiffness, buckling, fatigue, vibration, and composite failure modes - Lead preliminary and critical design reviews - Own CAD assemblies, production drawings, bills of materials, tolerances, and design releases - Manage mechanical interfaces between the airframe, propulsion, avionics, flight controls, landing systems, and other subsystems - Design aircraft mechanisms, including control surfaces, doors, landing gear, actuation systems, and deployable systems - Work with manufacturing to develop tooling, assembly processes, inspection methods, and repair procedures - Plan and support component, structural, subsystem, and vehicle-level testing - Investig