Senior Mechanical Engineer - TS/SCI Polygraph Required

Leidos is seeking an experienced Senior Mechanical Engineer to support critical national security missions in Reston, Virginia. This role focuses on the assessment, reverse engineering, and characterization of complex above-ground and subterranean facilities located in denied-access environments.The successful candidate will leverage strong engineering expertise to analyze facility designs, spatial layouts, operational workflows, and supporting infrastructure to determine functional capabilities and mission relevance. You will evaluate facility systems, model critical infrastructure, identify vulnerabilities, and provide technical insights that support complex intelligence and defense initiatives.This position requires an innovative engineer who can develop sound technical assessments in situations where complete information is inherently unavailable. The ideal candidate combines creativity, analytical rigor, and exceptional attention to detail with the ability to make informed decisions based on incomplete data. You will work alongside an interdisciplinary team of government and contractor professionals in a fast-paced, mission-focused environment while serving as a subject matter expert within your technical discipline.Primary ResponsibilitiesReverse Engineering & Facility CharacterizationAnalyze and characterize the physical and functional attributes of facility layouts, building architecture, and operational workflows within denied-access environments to determine facility purpose, capability, and operational capacity.Vulnerability AssessmentsEvaluate facility and infrastructure designs to identify security vulnerabilities, single points of failure, operational bottlenecks, and potential mission impacts.3D Modeling & SimulationDevelop high-fidelity 3D models and conduct engineering simulations to replicate facility operations, workflow efficiencies, and structural or mechanical limitations.Infrastructure AnalysisApply multidisciplinary engineering expertise to assess supporting facility systems, with a primary focus on Mechanical, Electrical, and Plumbing (MEP) integration and functionality.Technical Documentation & ReportingTranslate field-collected data, intelligence information, and engineering assessments into comprehensive technical reports, CAD/BIM products, and simulation-based analyses for Department of Defense stakeholders.Research & DevelopmentSupport customer-approved research and development initiatives independently or as part of a multidisciplinary team to advance analytical methodologies, modeling capabilities, and mission solutions.Subject Matter ExpertiseServe as a subject matter expert within your technical domain, providing engineering insight and technical guidance to support mission requirements.Required QualificationsCandidates for consideration must possess an in-scope and active TS/SCI Polygraph clearance and the ability/willingness to maintain this clearance while holding this position. U.S. Citizenship is required.​Demonstrated understanding of engineering principles, theories, and concepts and their application across a broad range of technical programs and mission challenges.Bachelor's degree with 12+ years of relevant experience, or a Master's degree with 10+ years of relevant experience.Relevant experience includes facility analysis, infrastructure vulnerability assessments, and mechanical engineering within commercial, Department of Defense, or Intelligence Community environments.MEP Systems Expertise: Strong multidisciplinary understanding of Mechanical, Electrical, and Plumbing (MEP) system design, integration, and operational functionality within complex industrial or military facilities, including specialized containment systems, filtration systems, and backup power infrastructure.Ability to identify industrial HVAC equipment, estimate system size and capacity, and assess operational capabilities through visual analysis.Ability to evaluate, organize, and utilize large datasets from diverse sources, including field-collected data, equipment technical manuals, and existing facility models.Expertise in 3D modeling, engineering analysis, and physical simulation methodologies.Experience interpreting engineering drawings, facility layouts, blueprints, and intelligence-derived technical data.Demonstrated ability to make sound technical judgments with incomplete information while clearly communicating assumptions, uncertainties, and recommended paths forward.Preferred QualificationsFive or more years of field experience working with industrial HVAC systems, including air-cooled and water-cooled chillers, condensers, cooling towers, air handlers, heat exchangers, boilers, and related equipment.Working knowledge of air management systems supporting critical environments, including medical laboratories, clean rooms, chemical laboratories, and similar specialized facilities.Hands-on experience with advanced Building Information Modeling (BIM) and engineering simulation tools, including Autodesk Revit, VENTSIM, ETAP, and other industry-standard CAD and modeling platforms.Experience supporting forensic engineering investigations, industrial accident analyses, or Department of Defense facility vulnerability studies.Professional Engineer (PE) license and/or Project Management Professional (PMP) certification.Experience identifying mechanical system vulnerabilities and developing effective mitigation or corrective action strategies.#ASBA#SnakeheadIf you're looking for comfort, keep scrolling. At Leidos, we outthink, outbuild, and outpace the status quo — because the mission demands it. We're not hiring followers. We're recruiting the ones who disrupt, provoke, and refuse to fail. Step 10 is ancient history. We're already at step 30 — and moving faster than anyone else dares.Original Posting:August 14, 2026For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above.Pay Range:Pay Range $131,300.00 - $237,350.00The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.SummaryLocation: Reston, VAType: Full time