Mechanical Integration and Test Engineer - Full Time Position

About HyLight

Power lines, gas pipelines and railways are still inspected the way they were 50 years ago: by helicopter. Expensive, noisy, and up to a tonne of CO₂ per flight hour.

We built the alternative. The HyLighter is a 12-metre autonomous airship running on hydrogen. It flies for up to 10 hours, almost silently, and spots a 1 mm defect from 25 metres up.

But the airship is only half the story. Every flight brings back massive amounts of LiDAR, imagery and methane data, and that’s where the value is. Our AI turns it into what operators act on: 50+ types of defects detected automatically, and leaks pinpointed across their network.

It’s not a prototype. HyLighters already fly missions for France’s largest energy and rail operators and have flown over the Palace of Versailles. Backed by Y Combinator, we just raised €13M to go from 4 airships to 15.

Working at HyLight

We design, build and fly every HyLighter, and turn its data into insight, all under one roof on a former airbase. Which means:

• You own it all the way. At a big aerospace company, you’d own a small piece of one subsystem. Here, you design it, test it, stand on the airfield when it flies, and see the client act on the data it brings back.

• Weeks, not years. Ideas go from whiteboard to flight test in weeks.

• Responsibility from day one. The founders’ average age is 27. Nobody here waits for permission.

We don’t care about titles or ticking every box. We care about what you build and the perspective you bring, so if your profile is different, apply anyway.

Personal Note from Louis (Airship Engineering Design Team Lead)

“We are tackling a massive challenge: making innovative airships fly while guaranteeing flawless operational availability. To achieve this, we refuse to work in silos. We are one polyvalent force driven by a 'Dual-Track Agile' mindset.

This role requires a rare balance. You won't just be a designer behind a screen; you will be an owner.

• In 'Discovery' Mode , you will explore and design the future HyLighter versions. You’ll have the autonomy to iterate, fail, and find the best solution to complex physical problems.

• In 'Delivery' Mode , you shift gears to efficiency and rigor. Here, we don't look for perfection; we look for reliability and speed. You’ll get your hands dirty in the workshop, ensuring that what we validate today flies tomorrow.

I am looking for someone who thrives in this duality. Someone who treats the shop floor with as much respect as the design studio, and who understands that a design isn't finished until it works in the field. If you are ready to take full ownership of the mechanical lifecycle and build something that truly matters, welcome to the team.”

Job Summary:

As a Mechanical Integration and Test Engineer , you will be the technical owner of the drone’s mechanical lifecycle. You will bridge the gap between "engineering perfection" and operational reality, ensuring our drones are robust, easy to assemble, and available for mission-critical inspections.

The Mission:

In collaboration with the Mech Team, your responsibilities will focus on Reliability, Industrialization, and Continuous Improvement:

• Creative Design: Lead the conceptual design of new mechanical subsystems and airframe evolutions. You will transform innovative ideas/prototypes into functional products through rapid iteration (CAD, 3D printing, machining), balancing sleek aesthetics, design for manufacturing with high-performance engineering.

• Reliability & Lifecycle Management: Establish fatigue models and design accelerated life tests (HALT/HASS) to predict component "End of Life" and maximize fleet availability. You will robustify the drone design to ensure reliable operation in challenging conditions.

• Root Cause Excellence: Implement a systematic Root Cause Analysis process for every field failure, ensuring rapid design updates and maintaining a strong feedback loop between engineering and operations.

Profile Sought:

• Background: Mechanical Engineering degree or equivalent practical experience.

• 3+ years experience in designing resistant outdoor/rugged mechanical systems (material fatigue, vibration). Experience in test planning (DoE), designing test equipment (fixtures, set-ups), actual testing, analyzing results, and writing reports as well as new test specifications.

• Versatility: You accept dual roles, comfortable alternating between deep design work (New Versions) and operational urgency (Production Support).

• Mindset: You possess a "Shop Floor" mindset, you enjoy spending time in workshops and do not consider work finished until the physical product is validated, not just the CAD file sent.

Technical Skills:

• Core Mechanics: solid CAD & DFM expertise (Design for Assembly, reduced part count), Material Mechanics (S-N curves/Wöhler, UV aging, creep, stress cycles).

• Reliability Data: Comfortable with statistical methods for reliability and data-driven approaches (Python).

• Manufacturing: Comfortable with processes such as 3D printing, welding, machining, or sheet metal work.

• Analysis Methods: Mastery of problem-solving methods like 5 Whys, Ishikawa to trace field failures to root causes.

Soft Skills:

• Highly organized and detail-oriented in documentation and execution

• Entrepreneurship: Willingness to find shortcuts and ways to do things efficiently.

• You enjoy getting your hands dirty and respect the insights of the technical team.

• Willingness to be present on-site and support operational teams during test and flight activities

• Curious, analytical, eager to learn, and proactive in problem-solving

• Good communication skills and collaborative mindset

Languages:

• French AND English: Fluent (Required)

What We Offer:

• 100% reimbursement of public transport pass (Navigo) or €800/year for sustainable commuting

• Bike provided for commuting

• Free lunch

• Bi-annual offsite trips with the whole team

• Excellent work environment: international team , team events, beautiful offices on a former airbase

Why You Should Join:

• Founder Mentality: We value extreme ownership and want people who think like founders-fast decision makers, natural problem solvers, and executers.

• Ground Floor Opportunity: You’ll be helping to shape and grow a revolutionary company with the resources to back it.

• Impact & Speed: Work in a fast-paced environment where your contributions will have immediate, tangible effects on the company’s success.

Interview Process:

• Introductory phone call (20 min)

• A 2 hour technical case study followed by a debrief with team members

• On-site meeting with the team and founders (1h)

• Reference calls

Location:

• Office : Base 217, Brétigny-sur-Orge, accessible via RER C.

• Lab and Warehouse access

• You’ll work side-by-side with experts in embedded, aerospace, and hydrogen propulsion systems-where your impact matters from day one