Principal Mechanical Design Engineer

Location: Barrow-in-Furness. We offer a range of hybrid and flexible working arrangements – feel free to discuss your options with your recruiter!

Salary: Circa £55,000

As a Principal Mechanical Design Engineer, you will:

• Lead the end-to-end development of complex fluid systems, crafting designs that meet rigorous performance and environmental standards.
• Create and review high-value engineering deliverables, from schematics and P&IDs to calculations, system descriptions, and 3D models.
• Drive advanced system analyses , including flow, pressure, thermal, and transient modelling to validate performance under challenging conditions.
• Select and assess critical equipment (pumps, compressors, valves, heat exchangers, filters, tanks) to ensure they thrive in tough submarine environments.
• Champion technology integrity by reviewing supplier documentation, ensuring compliance with shock, vibration, atmosphere, temperature, maintainability, and access constraints.
• Influence design quality and safety by contributing to reviews, hazard studies, verification activities, and resolving technical issues, modifications, and non-conformances.

Essential:

• Degree-level education, with Chartered Engineer status highly desirable.
• A solid background in mechanical, marine, process, or fluid systems engineering within a complex or highly regulated environment.
• Strong knowledge of fluid dynamics, thermodynamics, pressure-drop behaviour, transient analysis, and system performance modelling.
• Demonstrated technical expertise in the design, analysis, and integration of both compressible and incompressible fluid systems.

Desirable:

• Experience with industry-standard modelling and analysis tools such as FloMASTER, FluidFlow, MATLAB, CFD packages, ANSYS, or similar.

Benefits:

We offer a competitive pension scheme, employee share plans, and a wide range of flexible, discounted health, wellbeing, and lifestyle benefits. This includes a green car scheme, private health plans, and shopping discounts. You may also be eligible for an annual incentive!

This is an exciting opportunity to join the SSN AUKUS Platform Mechanical Integrated Delivery Team. As a Principal Mechanical Design Engineer, you will be a technical specialist for some of the submarine’s most critical fluid systems. You’ll take ownership of high-integrity mechanical designs that must perform flawlessly in one of the most demanding engineering environments in the world. This is your chance to work at the forefront of next-generation naval capability, tackling challenging technical problems and contributing directly to one of the UK’s most advanced defence programmes. Relocation support is available across all Submarine roles, subject to eligibility criteria.

At BAE Systems, you’ll make a real difference. We foster an inclusive culture that values diverse perspectives, rewards integrity and merit, and empowers you to reach your full potential. We welcome individuals from all backgrounds and strive to make our recruitment processes as inclusive as possible. If you have a disability or health condition that may affect your performance in certain assessments, please discuss potential reasonable adjustments with your recruiter.

Important Information:

Many roles at BAE Systems are subject to security and export control restrictions. Factors such as your nationality, any nationalities you may have previously held, and your place of birth can affect your eligibility for certain roles. All applicants must achieve at least the Baseline Personnel Security Standard. Many roles also require higher levels of National Security Vetting, typically necessitating 5 to 10 years of continuous residency in the UK for meaningful security vetting checks.

Closing Date: 13th February 2026

We reserve the right to close this vacancy early if we receive sufficient applications. If you’re interested, please submit your application as soon as possible!

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