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.