Systems Engineer Jobs in California

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.

The Senior Mechanical Systems & Configuration Engineer plays a key role in driving the development and integration of vehicle architecture, taking ownership of top-level mechanical configurations. This position works closely with the design engineering team to plan, coordinate, and execute complex mechanical engineering projects, ensuring seamless integration from initial concept through production. This role serves as the link between engineering, manufacturing, supply chain, and project management by maintaining product configurations, managing Bills of Materials (BOMs), coordinating engineering changes, and tracking project schedules and deliverables. The position also provides hands-on engineering support through CAD model and drawing updates, documentation control, and configuration management to ensure products are accurately released and maintained throughout their lifecycle.

Essential Responsibilities

• Lead the development and maintenance of high-level vehicle architecture and configurations, taking ownership of the overall mechanical design and ensuring seamless integration across vehicle systems.
• Drive a comprehensive understanding of the vehicle from a mechanical systems perspective, ensuring all components and subsystems work together to meet performance, functionality, and mission requirements.
• Manage and maintain engineering Bills of Materials (BOMs) for new and existing mechanical products.
• Maintain CAD assemblies, part configurations, and engineering documentation within the company's CAD and Product Lifecycle Management (PLM) systems.
• Perform minor mechanical CAD modeling and drawing revisions under the direction of design engineers, including dimension updates, tolerance changes, and documentation corrections.
• Coordinate the Engineering Change Request (ECR) and Engineering Change Order (ECO) process, ensuring design changes are accurately documented, reviewed, approved, and released.
• Monitor project schedules, engineering deliverables, milestones, and key performance metrics to support on-time project completion.
• Track design release status, prototype builds, testing activities, and production readiness.
• Ensure engineering documentation, drawings, and specifications comply with company drafting standards and revision control requirements.
• Support mechanical engineers with prototype builds, manufacturing documentation, and design verification activities.
• Coordinate with Manufacturing, Quality, Supply Chain, and Production to implement engineering changes and support new product introductions.
• Develop and maintain project dashboards, schedules, and status reports for engineering leadership.
• Identify opportunities to improve engineering workflows, documentation practices, and change management processes.

Required Qualifications

• Bachelor's or Master's degree in Mechanical Engineering, Mechanical Engineering Technology, Aerospace Engineering, or a related technical discipline
• Ability to understand complex mechanical systems including how individual components and subsystems interact and integrate to ensure overall vehicle functionality and performance.
• At least two years of experience creating and maintaining detailed mechanical drawings, assemblies, and manufacturing documentation using CAD software.
• Experience generating production-ready engineering drawings including dimensioning, tolerancing, and GD&T in accordance with company standards.
• Execute drawing revisions and engineering change orders (ECOs) to support ongoing product development and manufacturing.
• Experience developing and updating bills of materials (BOMs), assembly instructions, and release packages.
• Experience collaborating with mechanical engineers to convert conceptual and 3D designs into complete fabrication and manufacturing documentation.
• Experience with Product Lifecycle Management (PLM), or Product Data Management (PDM)
• Strong organizational, analytical, and problem-solving skills.
• Excellent communication and cross-functional coordination abilities.
• Proficiency in Microsoft Excel, Project, and other project tracking tools.

Preferred Qualifications

• Experience supporting new product introduction (NPI) programs.
• Hands-on experience in mechanical design, including the development, integration, and optimization of complex mechanical components and systems
• Familiarity with machining, sheet metal fabrication, welding, plastics, or mechanical assembly processes.
• Experience creating or revising mechanical drawings and technical documentation.
• Knowledge of Design for Manufacturing (DFM) and Design for Assembly (DFA) principles.

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.