Senior Integration & Test Engineer

About Castelion

Castelion is bringing a new approach to defense development and production: one that focuses on short, iterative design cycles, rapid testing in development, and modern commercial manufacturing strategies for production at scale. Were designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and to deter future conflicts.

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

Additional Requirements

• Must be willing to work extended hours and/or weekends as needed
• Must be able to travel up to 30% of the time

Leadership Qualities 

• Bias to Action and Creative Problem Solving. Desire and experience questioning assumptions in ways that lead to break through ideas that are ultimately implemented. Successfully bring in applicable processes/concepts/materials from other industries to achieve efficiency gains. Ability to personally resolve minor issues in development without requiring significant support.
• High Commitment, High Initiative. A successful candidate will have a genuine passion for Castelion's mission and consistently look for ways to contribute to the company's technical goals and prevent hardware blockers. Ability to work in a fast paced, autonomously driven, and demanding atmosphere. Strong sense of accountability and integrity.
• Clear Communicator. Proactively communicates blockers. Trusted in previous roles to be voice of company with regulators, suppliers, gate keepers and customers. Capable of tactfully managing relationships with stakeholders to achieve company-desired outcomes without compromising relationships. Emails, IMs and verbal interactions are logical, drive clarity, and detailed enough to eliminate ambiguity.

ITAR Requirements

• To conform to U.S. Government export regulations, applicant must be a (i) U.S. citizen or national, (ii) U.S. lawful, permanent resident (aka green card holder), (iii) Refugee under 8 U.S.C. § 1157, or (iv) Asylee under 8 U.S.C. § 1158, or be eligible to obtain the required authorizations from the U.S. Department of State.

Employment with Castelion is governed on the basis of competence and qualifications and will not be influenced in any manner by race, color, religion, gender, national origin/ethnicity, veteran status, disability status, age, sexual orientation, gender identity, marital status, mental or physical disability or any other legally protected status.

All employees are granted long-term stock incentives as part of their employment at Castelion. All employees receive access to comprehensive medical, vision, and dental insurance, and the company offers four weeks of paid time off per year.