Integration & Test Engineer, Senior

Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus, ownership, and excellence are decisive advantages - and we're building a world-class team to turn bold ideas into real capability. This is a rare opportunity to join at an early stage, where you'll have significant ownership, collaborate with exceptional teammates, and make a direct, measurable impact on our mission and the future of the company - regardless of your function. Senior Integration & Test Engineer As a Senior Integration & Test Engineer at Castelion, you will lead the transition of advanced defense hardware from prototype into full production — driving integration, test, and qualification of mechanical and electrical subsystems. In this role you'll help establish scalable manufacturing and test processes, support flight test campaigns, troubleshoot and resolve integration or test issues, and enable repeatable, production-ready builds of complex, mission-critical systems. Responsibilities • Take full ownership of assembly, integration, and test processes for complete hypersonic strike vehicle assemblies — including solid rocket motors, structural/composite components, mechanical, electrical, and avionics subsystems. • Become an expert in system level interactions and how the vehicle operates in the field. • Partner closely with design, manufacturing, and quality engineering teams to guide new hardware from concept through prototype, qualification, and production-ready status. • Evaluate designs for manufacturability, testability, and producibility; feed manufacturability and test requirements back into design reviews. • Develop, document, and qualify manufacturing, assembly, and test processes; create and maintain work instructions, test procedures, mBOMs, and quality/inspection standards. • Design and build tooling, test stands, jigs, fixtures, and integration/test equipment as needed to support both development and production efforts. • Lead hands-on build and test operations, working side-by-side with technicians and specialists to assemble flight-hardware, integrate subsystems, execute test campaigns (functional, static, environmental, acceptance), and perform go/no-go judgments. • Troubleshoot integration or test failures; rapidly lead root-cause investigations and corrective-action initiatives in partnership with quality and design teams. • Drive continuous process improvement: iterate on assembly flows and test procedures based on lessons learned, and scale processes as production volume grows. • Plan and manage capital-equipment, facility layout, and production-line upgrades to support increasing throughput, assembly complexity, and safety requirements. • Mentor and lead other engineers and technicians; cultivate a culture of accountability, technical rigor, safety, and continuous learning across the integration & test organization. • Work cross-functionally with supply-chain, vendors, fabricators, and subcontractors to ensure seamless, production-ready delivery of components and subsystems. • Operate comfortably in a fast-paced, resource-constrained startup environment, balancing technical excellence with aggressive schedule and business goals. Basic Qualifications • Bachelor's degree in mechanical, aerospace, or manufacturing engineering, or other technical degree • Minimum 5 years of professional experience within aerospace, defense, or a related high-reliability manufacturing/production environment — particularly in integration, test, or manufacturing roles. • Demonstrated history of taking hardware from R&D or prototype phase through to production. • Proficiency in CAD/CAM software (NX preferred) • Broad exposure to mechanical, structural/composite, electrical/avionics, and (optionally) propulsion or fluid/energetic systems — with ability to collaborate across disciplines. Preferred Skills and Experience • Prior experience writing, reviewing, and executing detailed test plans, procedures, and acceptance criteria — including formal qualification and environmental testing. • Experience with large-scale assembly operations — including heavy lifting, crane operations, facility logistics, and safety for large hardware flow • Familiarity with avionics / flight-hardware electrical harnessing and integration; comfortable integrating electronics, wiring, and power/data systems into mechanical/structural assemblies. • Experience with test-and-data-acquisition systems (DAQ), instrumentation, automation, and data analysis (e.g., Python, MATLAB, or similar). • Previous exposure to configuration-management, documentation management, build flow control, and manufacturing/ test-flow automation. • Familiarity with test equipment (instrumentation, data acquisition systems, and automated test setups) • Ability to use scripting or programming languages (e.g., Python, MATLAB, SQL) for test automation, data processing, or data post-processing • Proficiency with geometric dimensioning and tolerancing (GD&T) and managing complex tolerance stack-ups • Proven ability to carry hardware from R&D/prototype phases into high-volume manufacturing Castelion offers a generous benefits package. Please refer to the bottom of our Careers page for more details. Other Duties Please note this job description is not designed to cover or contain a comprehensive listing of activities, duties or responsibilities that are required of the employee for this job. Duties, responsibilities and activities may change at any time with or without notice. Additional Eligibility Requirements This position may require access to classified information or restricted U.S. Government sites, systems, or information, as determined by the Company and/or applicable U.S. Government requirements. If the position is so designated, your employment in the role may be contingent upon your ability to obtain and maintain the required U.S. Government security clearance or other government authorization, and to satisfy any citizenship or other eligibility requirements imposed by applicable law, regulation, executive order, or government contract requirements. You will be notified if and when such requirements apply. Affirmative Action/EEO Statement Castelion is an Equal Opportunity Employer. We are committed to providing equal employment opportunities to all applicants and employees without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, age, disability, genetic information, protected veteran status, or any other characteristic protected by applicable federal, state, or local law. Castelion is committed to providing reasonable accommodations to qualified individuals with disabilities throughout the application and hiring process. If you require a reasonable accommodation to complete an application, participate in the interview process, or otherwise participate in the hiring process, please contact hr@castelion.com. Requests for accommodation will be considered on an individual basis and handled in accordance with applicable law. Castelion is committed to fostering a workplace where employment decisions are based on qualifications, business needs, and the ability to perform the essential functions of the role, with or without reasonable accommodation. EAR/ITAR Requirements This position requires access to export-controlled information, and as such, employment (or hiring of a contractor) is contingent upon the candidate’s ability to access all applicable export-controlled information without additional export licensing being required by the Bureau of Industry and Security and/or the Directorate of Defense Trade Controls.