Important: All applicants must be able to obtain Security Clearance minimum 5 years UK residency Hybrid & Flexible working: This role offers flexible and hybrid working. The client site is a secure site where SC clearance is needed. A leading organisation within the defence and aerospace sector is seeking a Senior / Principal Mechanical Engineer to take ownership of complex electromechanical product development across the full lifecycle. This role is ideal for an engineer who enjoys both technical depth and broad lifecycle responsibility from early concept through to qualification, industrialisation, and in-service support. Youll be working on mission critical technology found in military and civil aircraft, ground vehicles, and unmanned systems. The position offers a collaborative environment, flexible working, and opportunities for professional growth. The Opportunity: This is a high-impact role requiring strong end-to-end NPD/NPI experience. You will be responsible for delivering robust, certifiable, manufacturable designs that meet demanding aerospace and defence requirements. The ideal candidate will bring a mix of advanced engineering expertise, strong analytical capability, and the ability to influence across multidisciplinary teams. Key Responsibilities: Lead full NPD/NPI activities from requirements capture through to qualification and industrialisation. Own lifecycle governance, design processes, and gate reviews. Produce and maintain high-quality technical documentation and design data. Deliver complex mechanical and electromechanical designs. Apply advanced GD&T and deliver high-quality FEA/analytical studies. Drive APQP/PPAP methodologies and embed strong DFM/DFT practices. Collaborate with cross-functional teams including Commercial, Finance, Quality, and Supply Chain. Support bids, estimates, risks, and project planning. Present technical proposals to internal and external stakeholders. Lead and support failure investigations with evidence-based solutions. Mentor and guide junior engineers and small technical work packages. Act as a technical reference point within your discipline. Essential Requirements: Strong experience within complex engineering environments (defence, aerospace, automotive, or safety-critical). Proven end-to-end NPD/NPI and full product lifecycle ownership. Hands-on APQP/PPAP experience. Advanced GD&T skills with ability to apply robust tolerancing schemes. Strong FEA/analytical capability with confident interpretation and reporting. CAD proficiency for assemblies, detailed drawings, and electromechanical layouts. Experience with PCB/enclosure design, including EMI/EMC considerations. Solid understanding of DFM/DFT and working with manufacturing/supply chain. Knowledge of aerospace/defence environmental standards (e.g. DO-160). Degree in Mechanical Engineering or equivalent. Desirable Requirements Chartered Engineer (CEng) or working toward it. Experience coaching/mentoring other engineers. Familiarity with PLM and configuration management tools. Knowledge of aerospace materials and high-integrity manufacturing methods. Experience supporting bids, estimates, or early technical scoping. Background in safety-critical sectors such as aerospace, defence, automotive, or motorsport. Company Benefits: Every employee is critical to the success of the business and as such they offer a range of flexible employee benefits along with career development opportunities. Flexible working within core working hours 25 days holiday (185hrs) with the option to buy/sell 5 days (37hrs) plus bank holidays 4 times your annual salary in life assurance Flexible benefits package Pension Scheme Sports and Social clubs Supportive and friendly working environment with regular team events. Even if you feel like you dont meet every requirement, we encourage you to reach out and apply.