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Salary
≈ $62k – $103k per year (Estimated)
Location
Hybrid (Belfast, United Kingdom)
Seniority
Principal · 3+ years exp
Employment
Full-Time

Confirmed on the employer's own hiring board on Oct 21, 2026. First seen by Alion on Oct 12, 2026. Thales Group scores A on the Alion truth index.

Overview
Company
Impact
Profile match
Thales is a French technology group whose lineage runs back to 1893, and it is one of Europe's largest defence and aerospace electronics companies. It builds radar, electronic warfare, sonar and command systems for armed forces, avionics and in-flight entertainment for aircraft, signalling for railways, and satellites through the Thales Alenia Space joint venture with Leonardo. A large cybersecurity and digital identity division, assembled through the Gemalto and Imperva acquisitions, supplies hardware security modules, encryption and the SIM and biometric documents used by banks and governments worldwide.
Location: Belfast, United Kingdom

Thales is a global technology leader with more than 83,000 employees on five continents. With over 7,500 people in the UK, operating across defence, space, aerospace, and digital security, we help build a future we can all trust. Thales supports the security and stability of our nation by providing extraordinary technology to our customers, as well as delivering social value to the UK with our products and services.

Principal Mechanical Engineer

Location: based in Belfast, minimum 3 days/ week in office (hybrid), with <10/>Other: permanent, full-time

Join Thales as a Principal Mechanical Engineer and take the lead in delivering cutting-edge defence technologies, combining technical excellence, leadership and innovation to help protect and defend what matters most.

What the role has to offer

  • Shape the Future of Defence Engineering - work on complex Weapon Systems, Missile Systems and Platform products, applying engineering first principles to develop innovative solutions that directly contribute to national and international security

  • Lead, Influence and Mentor - play a pivotal leadership role within a large Mechanical Design team, driving engineering best practice, influencing technical direction and developing the next generation of engineering talent

  • Thrive in a Growing Business with Outstanding Flexibility - join a business experiencing significant growth, with hybrid working, a half-day finish every Friday, performance bonus and a comprehensive benefits package that supports both your career and wellbeing

Our Opportunity

We are looking for a Principal Mechanical Engineer to lead the development of advanced defence technologies across our Integrated Airspace Systems portfolio.

Working within a multidisciplinary engineering environment, you'll deliver innovative mechanical solutions for Weapon Systems, Missile Systems and Platform products, applying engineering expertise to solve complex technical challenges and drive successful programme outcomes. As a senior technical leader, you'll champion engineering best practice, influence key design decisions and mentor engineers across the team, helping to build capability as our business continues to grow.

The ideal candidate will bring extensive mechanical design and hardware development experience, strong technical credibility and a proven ability to deliver robust, cost-effective solutions while leading and inspiring others.

Building a Future, we can all trust.

Integrated Airspace Protection Systems (IAS) - our main purpose is to protect and defend. We provide rapid integrated solutions for detection, coordination, fire control, engagement and support. We cover three sectors: Surface Attack & Air Defence (UK), Air Defence (International) and Air Operations & Services as well as Space.

What we offer you

We offer a competitive salary and benefits package designed to support our employees’ wellbeing and professional growth, which includes:

  • Performance-related bonus

  • Half day every Friday, usually finishing around 13:00

  • 28 days annual leave (plus bank holidays) with opportunity to buy up to 40 hours/year (pro rata)

  • 24 hours volunteering paid for

  • Private healthcare

  • Pension scheme

  • Life cover

  • 24/7 Employee Assistance Program and access to mental wellbeing app

  • Employee discount shopping schemes on major brands and retailers

  • Gym membership discounts

Key Responsibilities and Tasks

  • Lead Mechanical Design & Development - Deliver detailed mechanical designs and engineering solutions for new and existing products, applying engineering first principles and utilising appropriate CAE tools, analyses, simulations, prototypes and testing methods

  • Drive Technical Excellence & Decision Making - Analyse complex mechanical engineering challenges, evaluate options, and propose justified technical, technological and methodological solutions aligned with approved architectures, performance requirements and customer needs

  • Manage Product Definition & Documentation - Create and maintain accurate engineering documentation, including technical drawings to BS 8888 standards, product specifications, development plans, data packs and configuration-controlled design records

  • Support Product Lifecycle & Change Management - Lead engineering change activities, ensuring the integrity of Bills of Materials (BOMs), manufacturing data, product configurations and associated engineering processes throughout the product lifecycle

  • Collaborate Across Functions to Deliver Manufacturable Solutions - Work closely with engineering, production, procurement and other stakeholders to develop robust, cost-effective and manufacturable design solutions that meet quality, cost and schedule objectives

  • Plan, Monitor & Improve Engineering Delivery - Organise and oversee mechanical engineering activities, monitoring technical progress, compliance with target costs and lead times, and driving continuous improvement in engineering quality, performance and delivery

  • Provide Technical Leadership & Mentoring - Mentor, guide and support engineers within the team, promoting best practice, sharing knowledge, and fostering a culture of technical excellence and professional development

About You

At Thales, we are committed to equal opportunities and welcome all talented individuals to consider joining our team. So even if you don't match every statement below but feel you have some of the experience, knowledge or skills needed for this role, we encourage you to apply. It will take all of us working together to deliver solutions to the world’s most critical challenges.

  • Acquired a degree (or equivalent qualification) in an engineering discipline, preferably Mechanical Engineering

  • Proven proficiency in 3D CAD design, particularly Creo and/or CATIA, with extensive experience producing detailed mechanical designs and engineering drawings to BS 8888 standards, including the application of GD&T principles

  • Demonstrated experience using PLM systems (such as Windchill), managing product structures, Bills of Materials (BOMs) and engineering change processes whilst maintaining configuration and process integrity

  • Proven ability to apply Design for Manufacture (DfM), DFX methodologies and continuous improvement principles to develop cost-effective, robust and manufacturable design solutions

  • Demonstrated experience applying international and industry standards, with knowledge of Defence Standards and environmental testing methodologies to support product verification and validation activities

  • Proven capability in solving complex engineering problems, making sound technical decisions and utilising analysis, simulation and CAE tools (e.g. Ansys, Creo Simulate, SolidWorks Simulate) to support design development

  • Demonstrated success working within multidisciplinary project and product teams, managing multiple priorities and delivering engineering outputs against programme milestones, cost targets and schedules

  • Proven ability to lead projects, teams and technical activities, including planning, monitoring and reporting progress to ensure successful delivery of engineering objectives

  • Demonstrated strong communication, stakeholder management and collaboration skills, with experience working effectively with customers, suppliers and cross-functional teams

  • Proven commitment to developing others through mentoring, coaching and technical leadership, fostering capability growth and engineering best practice across the team

If you're an experienced Mechanical Engineering leader ready to make an impact on some of the world's most advanced defence programmes, we'd love to hear from you. Apply today and help us build a future we can all trust!

Security Clearance Requirement:

Due to the nature of the work that we do at Thales, many of our roles are subject to security restrictions. This role requires Security Clearance (SC). It would be advantageous if currently held, however, if not currently held, it is a requirement that the successful applicant undergo, achieve, and maintain SC Clearance prior to commencing employment.

To be eligible for full SC, you generally need to have resided in the UK for the last 5 years. In some circumstances, a minimum of 3 years’ residence in the UK over the last 5 years may be accepted, with additional overseas checks.

Please visit the UKSV website for further guidance: https://www.gov.uk/government/publications/united-kingdom-security-vetting-clearance-levels/national-security-vetting-clearance-levels.

At Thales, we ensure equal opportunities, pay and working conditions for all. The benefits we offer include private medical insurance, buying or selling annual leave, cycle to work schemes, employee discounts, paid volunteering day, stocks and shares, annual bonus and much more depending on the role. Read more about our benefits here.

We are committed to creating a workplace where everyone feels valued for who they are and the unique strengths they bring. Discover more about our programmes, employee networks, wellbeing policies, and inclusive features here.

If this role isn’t quite right for you, we encourage you to join our talent community where your details will be shared with our recruitment teams for other potential opportunities. Join the Talent Community here.

Join Thales in the UK - Innovate with us and shape the future!

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