Systems Test Engineer

About the role

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. We're designing, building, and testing next generation long range strike weapons systems to give America and its Allies a definitive edge and deter future conflicts.

Systems Test Engineer

We are looking for a Systems Test Engineer to own the test requirements, automated test station development, integration, validation and performance characterization. In this role, you will take end-to-end ownership for test equipment deployment in hardware domains such as Control Actuation System (CAS), Ignition Safety Devices (ISDs), thrust vector control systems, Flight Avionics electronics, and other instrumentation circuit boards and sub-assemblies. You will lead the development of rigorous test infrastructure, design and execute test campaigns, and help define the production test performance envelope from components to circuit boards, to sub-systems.

This role blends hands-on testing with systems-level thinking. You'll work closely with controls, software, avionics, and mechanical teams to ensure our avionics hardware is verified against realistic, mission-representative conditions.

Responsibilities

Develop and execute comprehensive test plans across component, subassembly, and integrated system levels.
Design & Build test fixtures, HIL environments, and automated test rigs to provide test conditions and automated test profiles.
Validate performance metrics such as power consumption, digital communication, RF performance, torque, response time, bandwidth, and thermal/vibe behavior under nominal and fault scenarios.
Instrument and log tests for precise characterization and traceability.
Lead root-cause investigations for performance anomalies or test failures.
Collaborate with flight hardware development to refine designs based on test results and failure data.
Drive qualification testing and environmental testing campaigns (vibe, thermal, EMI) for flight hardware.
Deploy and prove test equipment designs for components, CCA, and sub-assembly test stations.

Basic Qualifications

B.S. or M.S. in Mechanical, Mechatronics, Aerospace, or Electrical Engineering.
Experience testing high power sub-assemblies, high-speed digital interfaces, actuators, motion control systems, and RF sub-assemblies for aerospace, automotive, robotics, or defense applications.
Hands-on experience designing automated test equipment from the ground up utilizing equipment such as power suppliers, DMMs, oscilloscopes, switch matrixes, network analyzers, spectrum analyzers, signal generators, electronic loads, etc.
Familiarity with embedded control systems and communication protocols (CAN, RS-422/485, SPI, Ethernet, Automotive Ethernet).
Proficient in using instrumentation and data acquisition systems (e.g., Python, C++,Protobuffs, custom scripts)
Demonstrated ability to work independently and lead multi-disciplinary integration efforts.

Preferred Skills and Experience

Experience in RF testing fundamentals or more advanced knowledge of Radar architecture
Experience with software development for test automation for digital, power, and RF electronics (Python preferred)
Experience controlling test instrumentation using SCPI, VISA, or PyVISA commands
Experience developing GUIs or dashboards
Experience in writing custom scripts for data analysis & database creation
Experience writing software for Environmental Chambers and/or RF Chambers
Exposure to flight-like test environments, including environmental stress screening (ESS)
Experience with fault injection, failure mode testing, and reliability qualification for mission-critical systems
Working knowledge of C/C++ or Python for custom test tooling or embedded systems debugging
Background supporting flight test or launch operations.

What We Value

Hands-on rigor: deep understanding of systems through direct testing and failure analysis.
Autonomy and ownership: you don't wait for direction you seek out what needs to be tested and make it happen.
High standards for reliability, data quality, and test repeatability.
Systems-level thinking: understanding how actuator behavior affects broader vehicle performance.

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.

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.