How to Become an EASA Part-66 Licensed Engineer — Complete Guide

What Is a Part-66 Licensed Engineer?

A Part-66 licensed engineer is a professional authorised by a European national aviation authority, under Regulation (EU) No 1321/2014, to inspect, repair, modify, and certify aircraft. Licensed engineers act as certifying staff: they are responsible for maintenance records and for signing the release to service (CRS) — the legal certification that an aircraft is airworthy and safe to fly. Without a licensed engineer signing off on maintenance work, no aircraft can legally return to service under Part-145.

The profession is regulated by Part-66 (Annex III of Regulation (EU) No 1321/2014) for licensing, Part-145 for maintenance organisations, and Part-M/CAMO for continuing airworthiness — a framework that is evolving through Regulation (EU) 2023/989. Your national aviation authority oversees the certification process, approving maintenance training organisations, administering or supervising the module exams, and issuing the licence. The official syllabus, Part-66 Appendix I, defines the knowledge modules and depth levels that every candidate must master.

Step 1: Meet Eligibility Requirements

Before you can begin formally working toward your Part-66 licence, you must satisfy the basic eligibility criteria established by 66.A.20:

• Age — You must be at least 18 years old to hold a Part-66 licence. There is no upper age limit.
• Language proficiency — You must be able to read, write, and communicate in the language in which the examination is taken. Aviation maintenance documentation, manuals, and regulatory references are published in English.
• Education — There is no formal education requirement, but secondary education with strong foundations in mathematics, physics, and electrical principles is highly beneficial for the module exams.
• Nationality — EU citizenship is not required. Non-EU nationals can train, sit the module exams, and obtain a Part-66 licence through the national aviation authority of the member state where they qualify.
• Clean aviation record — The authority may review your background for aviation-related infractions, safety violations, or criminal convictions that could affect your suitability for certification.

Meeting these prerequisites ensures that you have the foundational capacity to handle the technical, regulatory, and safety demands of the profession. The certification process is demanding by design — public safety depends on the competence of every certifying engineer.

Step 2: Choose Your Training Path

Part-66 recognises two main pathways to qualifying for the licence. Your choice depends on your educational background, learning style, financial situation, and career timeline.

Path A: Attend an EASA-Approved Maintenance Training Organisation (MTO)

Graduating from an EASA-approved maintenance training organisation (formerly Part-147) is the most structured and fastest route to certification. Under 66.A.30, recognised training reduces the experience requirement — from 5 years to 3 years for B1.1, B1.3 and B2 with a recognised technical diploma, and from 4 years to 3 years for B1.2. Approved programmes are offered by organisations across Europe, including:

• Lufthansa Technical Training — Hamburg and Frankfurt, Germany. One of the largest and most respected Part-66 training providers in the world.
• CAE — Madrid, Brussels and Paris. EASA-approved Part-66 academies with strong airline and MRO placement.
• IAT (International Aviation Training Academy) — Leipzig and Hamburg, Germany. B1.1 and B2 programmes in English and German.
• Air Service Training (AST) — Perth, Scotland. Over 90 years of aircraft maintenance training.
• ESM — Dublin, Ireland. Part-66 theory and practical training with day and evening options.
• FTEJerez — Jerez de la Frontera, Spain. Part-66 training delivered in English.
• SR Technics — Zurich, Switzerland. MRO-based Part-66 training with strong practical exposure.
• National technical colleges across the EU — Many colleges and universities of applied sciences run EASA-approved Part-66 tracks alongside engineering degrees.

The key advantage of the MTO path is speed and structure. Most programmes run 18-36 months, and graduates can move directly to the module exams and the assessment of competence. Many organisations also build module exam preparation into the curriculum and administer the exams on site.

Path B: Apprenticeship / On-the-Job Experience (OJT)

The experience route involves working in aircraft maintenance under the supervision of certifying staff while documenting your experience in a logbook. Per 66.A.30, you need 2 years for category A, 4 years for B1.2, 5 years for B1.1/B1.3/B2, and 2 years for B3. While it takes longer than the school route, apprenticeship offers the advantage of earning a wage from day one and building real-world industry experience. Many apprentices find that the practical, on-the-job learning environment suits their learning style better than a classroom.

Some candidates take a blended approach: completing an MTO programme first to build theoretical knowledge and qualify for the reduced experience period, then working in a maintenance shop while studying for the module exams. This combined path is increasingly popular and offers the best of both worlds.

Step 3: Choose Your Licence Category

Before you begin the examination process, you need to decide which licence category you will pursue. This decision affects which modules you take and the scope of work you will be authorised to certify:

• Category A (line maintenance) — Authorises a limited set of line maintenance tasks, typically inspections and simple replacements, under B1/B2 supervision. 2 years of experience.
• Category B1 (mechanical) — Authorises maintenance of the airframe, mechanical systems, and engines, in four subcategories: B1.1 (aeroplane turbine), B1.2 (aeroplane piston), B1.3 (helicopter turbine), B1.4 (helicopter piston).
• Category B2 (avionics) — Authorises maintenance of electrical and electronic systems: communication, navigation, instruments, radar, autopilots, and digital systems.
• Category B3 — A combined licence for small, non-pressurised piston helicopters, covering both mechanical and avionics work on those types.

Most engineers pursue a B1 or B2 category — employers overwhelmingly expect a full certifying category. For a detailed comparison of the categories, see our guide on B1 vs B2 licence categories.

Step 4: Pass the Part-66 Module Exams

This is the most academically demanding phase of the certification process. You must pass the module exams for your category, each covering the subject areas defined in Part-66 Appendix I. The pass mark for every module exam is 75% (66.A.25).

The 17 Modules

• Fundamentals — M1 Mathematics, M2 Physics, M3 Electrical Fundamentals, M4 Electronic Fundamentals, M5 Digital Techniques/Electronic Instrument Systems.
• Structures and practices — M6 Materials and Hardware, M7 Maintenance Practices, M8 Basic Aerodynamics, M9 Human Factors, M10 Aviation Legislation.
• Category-specific — M11 Aeroplane Aerodynamics Structures and Systems, M12 Helicopter Aerodynamics Structures and Systems, M13 Aircraft Aerodynamics Structures and Systems, M14 Propulsion, M15 Gas Turbine Engine, M16 Piston Engine, M17 Propeller.

Each category maps to its own subset of 12-14 modules, examined at knowledge levels 1 (overview), 2 (detailed), or 3 (in-depth) as defined in Appendix I. The exams are computer-based, administered by approved training organisations or national aviation authorities. Module exam credits are valid for 10 years, and each module may be attempted a maximum of 3 times consecutively — after the third failed attempt you must wait one year, with at least 30 days between attempts.

Many candidates find that using an AI-powered platform like Skylicence Europe significantly accelerates their preparation by providing adaptive practice questions, real exam simulations, and instant AI tutor support.

For detailed study strategies and a complete breakdown of each module, including question quotas, time limits, and common pitfalls, see our dedicated EASA Part-66 module exams guide.

Step 5: Complete Experience, Assessment of Competence, and Certification

Once you have passed your module exams, you must complete your experience requirements (unless reduced by recognised training) and then pass the assessment of competence.

Practical Experience Requirements

Part-66 requires 2 years of experience for category A, 4 years for B1.2, 5 years for B1.1/B1.3/B2, and 2 years for B3, per 66.A.30 — reduced by recognised training. Your experience must be documented in a logbook, with entries countersigned by the certifying staff who supervised you. The experience must cover the procedures, practices, materials, tools, and equipment generally used in aircraft maintenance, organised across the relevant competency areas:

• Inspection and testing procedures
• Repair and modification of aircraft structures and systems
• Troubleshooting and fault diagnostics
• Maintenance record-keeping and certification documentation
• Use of technical publications, ADs, and approved data

Assessment of Competence

This is the final and most comprehensive assessment. B1 and B2 candidates complete an assessment of competence (66.A.40) conducted by their national authority or an authorised training organisation, covering the practical tasks appropriate to the category. The assessor evaluates your technical knowledge, safety awareness, reference to approved data, tool use, and regulatory compliance. You present your logbook and module certificates at the start of the session.

Certification and Beyond

After passing all components, your national aviation authority issues the Part-66 licence with the categories you qualified for. You are then authorised to perform and certify aircraft maintenance within your category — and your licence is valid across all EASA member states. Congratulations — you are now licensed certifying staff!

Timeline: How Long Does It Take?

The total time from starting your training to earning your Part-66 licence varies significantly depending on your chosen path:

• MTO graduate (full-time) — 2 to 3.5 years total. Most programmes run 18-36 months, including built-in module exam preparation.
• Apprenticeship route — 2.5 to 5 years total, depending on category. 2-5 years of documented experience + module exams and assessment interspersed.
• Accelerated path (MTO + focused exam prep) — 18 to 30 months. Using tools like Skylicence Europe to compress exam preparation can shave months off the timeline.

How Skylicence Europe Helps You Become a Licensed Engineer Faster

Skylicence Europe is an AI-powered study platform designed specifically for the EASA Part-66 module exams. Our platform covers the complete Part-66 Appendix I syllabus with adaptive technology that helps you learn faster and retain more.

• Full module coverage — 4,464 questions mapped to all 17 modules and all 8 licence categories, with the official 75% pass mark.
• Adaptive AI difficulty — The platform adjusts in real time to focus on your weak areas while reinforcing strong ones.
• Real exam simulations — Timed practice tests replicate the official module quotas and time limits to build speed and confidence.
• AI Tutor — Get instant, syllabus-referenced explanations of any topic in plain language.
• Progress tracking — Know exactly where you stand on every module before you book your exam.

The FREE plan gives you one licence category free — with all of its modules included. PRO is EUR 29.99/month and LIFETIME is a one-time EUR 199.

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