Principal Engineer - Mechanical Systems

Job Title:                     Principal Engineer – Mechanical Systems

Location:                     Plymouth + Hybrid Working Arrangements

Compensation:           Competitive + Benefits

Role Type:                   Full time / Permanent

Role ID:                        SF69840

Lead complex mechanical systems engineering at the heart of the UK’s defence infrastructure

At Babcock we’re working to create a safe and secure world, together, and if you join us, you can play your part as a Principal Engineer – Mechanical Systems at our Devonport Royal Dockyard site.

The role

As a Principal Engineer – Mechanical Systems, you’ll play a critical role in maintaining and controlling modifications to mechanical building services across both nuclear‑implicated and non‑nuclear facilities. Your work will span the full engineering lifecycle, from requirements capture and design development through implementation, close‑out, through‑life support, decommissioning and disposal.

Day-to-day, you’ll have an opportunity to shape engineering solutions that underpin national defence, ensuring compliance with nuclear site licence conditions, regulatory frameworks and industry design standards. You’ll collaborate with specialists across engineering disciplines, influence project delivery from concept to completion, and help develop innovative, safe and efficient systems. It’s challenging work with purpose, and a powerful platform for your continued professional development.

• Ensure compliance with nuclear site licence conditions, statutory legislation, regulatory frameworks and industry‑recognised design codes.
• Prescribe the Mechanical Building Services requirements for assigned design projects.
• Develop and deliver design solutions across the full design process, including Start‑up, Concept, Scheme, Detailed and Implementation phases.
• Support design reviews to ensure subcontractor designs meet company, regulatory and industry standards.
• Manage the production, checking and approval of technical documentation and engineering drawings.

This role is full time, 35 hours per week and provides hybrid working arrangements with a minimum of 2 days onsite.

Essential experience of the Principal Engineer – Mechanical Systems

• Familiarity with energy reduction strategies and decarbonisation approaches for new and existing buildings, including passive design solutions.
• Extensive understanding of mechanical engineering principles for steam and condensate, industrial gases, fresh and demineralised water, HVAC (including nuclear‑related), LEV and domestic services.
• Detailed knowledge and experience of BREEAM, DREAM and Building Regulations.
• Experience working within a design consultancy or contractor design environment, with the ability to manage a small team of engineers.
• Strong understanding of applicable regulations, legislation and technical standards related to mechanical services system design.

Qualifications for the Principal Engineer – Mechanical Systems

• Degree‑level qualification (Level 7) in Mechanical Engineering or Building Services Engineering, or a lower-level qualification with significant supporting experience.
• Chartered Engineer status with CIBSE or IMechE or working towards Chartered status.

• Additional mechanical systems, nuclear or building‑services‑related professional training or certifications - Desirable

Security Clearance

The successful candidate must be a sole UK national who is able to achieve and maintain Naval Nuclear Propulsion Information (NNPPI) security clearance for this role.

Many of the positions within our company are subject to national security clearance and Trade Control restrictions. This means that your eligibility for certain roles may be affected by your place of birth, nationality, current or former citizenship, and any residency you hold or have held. Further details are available at United Kingdom Security Vetting: clearance levels - GOV.UK (www.gov.uk)

What we offer

• Generous holiday allowance
• Matched contribution pension scheme, with life assurance
• Access to a Digital GP, annual health check, and nutritional consultations through Aviva DigiCare+
• Employee share scheme
• Employee shopping savings portal
• Payment of Professional Fees
• Reservists in the armed forces receive 10-days special paid leave
• Holiday Trading is a benefit that allows UK Babcock employees to buy additional leave or to sell up to one working week of annual leave from their annual entitlement. This Window opens February through to March annually.
• ‘Be Kind Day’ enables employees to take one working day's paid leave a year (or equivalent hours) to undertake volunteering work with their chosen organisation or registered charity
• Excellent development opportunities and benefits package including an employee assistance programme supporting physical, mental and financial wellbeing.

Babcock International

For over a century Babcock has helped to defend nations, protect communities and build a better world. To continue, we must adapt, advance and be a sustainable business with a shared goal.

We are a disability confident committed employer. If you have a disability or need any reasonable adjustments during the application and selection stages, please email careers@babcockinternational.com with the subject header ‘Reasonable adjustments requirement’. We’re committed to building an inclusive culture where everyone’s free to thrive. We are happy to talk about flexible working – please ask about alternative patterns of work at interview.

Closing date: 05/02/2026

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