The Complete EASA Part-66 Licensing Guide

Introduction to EASA Part-66 Licensing in Europe

The EASA Part-66 Aircraft Maintenance Licence (AML) — commonly known as the AME licence — is the cornerstone of aviation maintenance in Europe. Governed by Annex III (Part-66) of Regulation (EU) No 1321/2014, the licence authorises qualified professionals to certify maintenance work and release aircraft back into service as certifying staff. Without licensed certifying staff, no aircraft in Europe can legally operate after maintenance.

The licence is issued by the competent authority of an EASA member state and is valid throughout the European Union and the wider EASA community. There are eight licence categories: Category A (turbine or piston), B1.1, B1.2, B1.3 and B1.4 (aeroplane and helicopter mechanics), B2 (avionics) and B3 (light helicopters and small aeroplanes up to 2 000 kg). Every category is built on a subset of the 17 basic knowledge modules (M1–M17), examined at three knowledge levels (1, 2 and 3).

The Part-66 licence is respected globally as a mark of technical excellence in aviation maintenance. Licensed engineers from Europe work across airlines, maintenance organisations (MROs), helicopter operators and general aviation — and the licence is recognised through bilateral agreements in many countries around the world.

Licence Categories: A, B1.1–B1.4, B2 and B3 Explained

Choosing your licence category is the single most important planning decision you will make on your Part-66 journey. Each category leads to a different area of expertise with distinct responsibilities, work environments and earning potential. Below is a detailed breakdown.

Category A — Line Maintenance Certifying Staff

Category A authorises you to perform simple line maintenance tasks and issue certificates of release to service (CRS) within the limits of tasks specifically listed on your licence, after carrying out the required checks. It is the fastest route into certifying status:

• Scope — simple line tasks, servicing, inspections and troubleshooting within defined limits
• Modules — 12 basic knowledge modules (M1–M10, plus the aeroplane or helicopter module and the propulsion module)
• Experience — 3 years of practical experience (reduced with MTO training)
• Progression — most Category A holders upgrade to B1 or B2 later

Category B1 — Aeroplane and Helicopter Mechanics (B1.1–B1.4)

Category B1 covers the maintenance of aircraft structures, powerplants and mechanical and electrical systems, plus work on avionic systems within the limits of line replacement units (LRUs). It is split into four subcategories by aircraft type:

• B1.1 — Aeroplanes with turbine engines (e.g. Airbus A320 family, Boeing 737): modules include M11A and M15, 13 modules in total
• B1.2 — Aeroplanes with piston engines (e.g. Cessna 172, Piper PA-28): modules include M11B and M16
• B1.3 — Helicopters with turbine engines (e.g. Airbus H125, Leonardo AW139): modules include M12 and M15
• B1.4 — Helicopters with piston engines (e.g. Robinson R22, R44): modules include M12 and M16

B1.1 and B1.3 require 5 years of experience (3 with an MTO course, 2 if it included practical training); B1.2 and B1.4 require 3 years (2, or 1 with an MTO course).

Category B2 — Avionics

Category B2 covers the maintenance of electrical, electronic, instrument and communication systems on any aircraft type, aeroplane or helicopter. B2 engineers are the specialists behind the flight deck:

• Electrical power generation and distribution
• Instruments, autoflight systems and navigation equipment
• Communication and surveillance systems (radio, transponders, weather radar)
• Digital data buses and electronic display systems (EFIS, ECAM, EICAS)
• Module M13 covers aerodynamics, structures and systems from an avionics perspective — 180 multiple-choice questions, splittable into two examinations

B2 requires 5 years of experience (3 with an MTO course, 2 if it included practical training). B2 engineers are in constant demand at airlines, MROs and avionics shops.

Category B3 — Light Helicopters and Small Aeroplanes

Category B3 is designed for maintenance on light helicopters and small aeroplanes with a maximum take-off mass (MTOM) of 2 000 kg or less, such as the Robinson R22, Cessna 172 and Piper PA-28. It uses adapted modules (7B, 9B, 11C, 16, 17B) tailored to light aircraft work and requires 3 years of experience (2 with an MTO course, 1 if it included practical training). It is the natural licence for general aviation and flying school maintenance.

Category C — Base Maintenance Certifying Staff

Category C authorises you to certify base maintenance (heavy) work and release aircraft after major checks. It is not an entry-level licence: applicants must already hold a B1 or B2 licence (or equivalent), which satisfies the basic knowledge requirement, and must have completed type training on the aircraft in question. Many senior engineers progress from B1/B2 to C after years of experience.

Comparison Table: EASA Licence Categories

The 17 Basic Knowledge Modules (M1–M17)

The Part-66 basic knowledge requirements are defined in Appendix I of the regulation. Nobody takes all 17 modules — each licence category maps to its own subset of 12–13 modules. The module examinations follow the standard defined in Appendix II: question counts, time limits and the 75% pass mark.

Every module is examined at a defined knowledge level per category, from Level 1 (familiarisation: know the principal elements and use typical terms) through Level 2 (general knowledge: understand theoretical fundamentals and apply detailed procedures) to Level 3 (detailed knowledge: master the theory, interpret results and take corrective action). Check the Appendix I syllabus for your category to see exactly which level applies to each subject.

Part-66 Module Examinations (Appendix II Standard)

The module examinations are the written component of certification, defined in Appendix II of Part-66. They are administered by approved maintenance training organisations (MTOs, formerly Part-147) or by your national aviation authority, in the national language and in English.

Key facts about the module examinations:

• Format: Multiple-choice questions (MCQ), plus four essay questions in total — 2 on Module 7 (Maintenance Practices), 1 on Module 9 (Human Factors) and 1 on Module 10 (Aviation Legislation)
• Pass mark: 75% on every module examination — not 70%
• Question counts: defined per module and category (e.g. M1 Mathematics: 32 questions / 40 minutes for B1; M11A: 140 questions / 175 minutes; M15: 92 questions / 115 minutes; M7A: 80 questions + 2 essays / 100 minutes + 40)
• Total volume: B1.1 candidates sit 692 questions across 13 modules; B2 candidates 652 across 12; Category A around 424–468
• Retake rules: minimum 30 days between retakes of the same module; maximum 3 consecutive attempts per module, then a 1-year waiting period
• Validity: module passes remain valid for 10 years before your licence application (66.A.25); older passes can receive examination credit from the competent authority

For detailed module-by-module breakdowns, practice questions and study strategies, visit our EASA Part-66 resource hub and exam FAQ.

Step-by-Step Pathway to Your EASA Part-66 Licence

Step 1: Meet Basic Eligibility Requirements

Before beginning the certification process, you must satisfy these prerequisites:

• Be at least 18 years old
• Be able to read, write and communicate in the language in which the examinations are administered — essential for maintenance manuals and official documentation
• Have no criminal record that would prevent you from holding a licence or exercising certifying privileges
• No university degree or medical certificate is required — a solid technical background is what matters

Step 2: Choose Your Licence Category

The regulation does not lock you into one path — you choose the category that fits your career goal:

Category A — fastest route into line maintenance certifying tasks. B1.1/B1.2 — aeroplane mechanic (turbine/piston). B1.3/B1.4 — helicopter mechanic (turbine/piston). B2 — avionics on any aircraft type. B3 — light helicopters and small aeroplanes up to 2 000 kg. Your choice determines your module subset, your examinations and your experience requirement.

Step 3: Choose Your Training Path

You can train through an approved maintenance training organisation (MTO, formerly Part-147) or build experience on the job:

Path A: MTO Approved Training — Attend an approved maintenance training organisation at institutions such as:

• Airbus Training — Toulouse, France (and other European sites)
• Lufthansa Technical Training — Hamburg, Germany
• ESMA Aviation Academy — Montpellier, France
• City of Glasgow College — Glasgow, United Kingdom
• FTA / Global Aviation — various European locations
• National CAA-accredited schools — across every EASA member state

MTO basic training courses typically last 2–3 years, combine theory with supervised practical training, and dramatically reduce the experience requirement — often to 2 years or less.

Path B: On-the-Job Experience — Accumulate 5 years of practical experience for B1.1, B1.3 and B2, or 3 years for A, B1.2, B1.4 and B3 (66.A.30), working at an approved maintenance organisation. This route allows you to earn while you learn and gain real-world experience from day one.

Step 4: Pass Your Category's Module Examinations

Study for and pass every module examination of your category with at least 75%. Use Skylicence Europe's AI-powered practice platform to generate adaptive practice questions, simulate timed module exams, and track your progress across every Appendix I subject area. You can also try free sample questions on our free practice questions page.

Study tip: focus on the foundational modules first. Most candidates start with M1 (Mathematics) and M2 (Physics) before moving on to the heavy systems modules such as M11 or M12. Allow 4–6 weeks of dedicated study per module — and never book an exam before you consistently score above 85% in timed practice.

Step 5: Document Your Practical Experience

Document your hands-on maintenance experience meticulously. Each logbook entry should include the date, aircraft type, task description, reference to approved data (manufacturer manuals, service bulletins, airworthiness directives) and the signature of your supervising engineer. Experience completed before an MTO course counts at 100%; experience gained during the course counts at 50%; and a fully approved MTO course can satisfy the requirement entirely.

Step 6: Apply to Your National Aviation Authority

Submit your application to the competent authority of the EASA member state where you completed your basic training or accumulated your experience. Your package must include:

• Completed licence application form for your national authority
• Module examination results for every module of your category
• Verified experience record (logbook) — or proof of graduation from an approved MTO course
• Proof of identity and any previous licences or qualifications

National authorities include the DGAC (France), LBA (Germany), AESA (Spain), ENAC (Italy), the CAA (United Kingdom) and the equivalent bodies in every member state. The authority reviews your file and issues your Aircraft Maintenance Licence.

Step 7: Receive Your Licence and Keep It Valid

Congratulations — you are now licensed certifying staff, authorised to certify maintenance across Europe. From here, the growth path is open:

• Add aircraft type ratings through approved type training courses
• Upgrade from Category A to B1 or B2 with additional modules and experience
• Progress to Category C for base maintenance release after sufficient experience
• Plan for licence renewal every 5 years with continued recent maintenance activity

Licence Validity and Renewal

Under the revised Part-66 framework, licences are issued with a validity of 5 years and must be renewed. Renewal is typically based on evidence of continued relevant maintenance activity — generally at least 6 months of recent experience within the preceding 24 months. Keep your logbook current, stay active in maintenance, and track your renewal date carefully: an expired licence means no certifying privileges until renewed.

Our 30-day study checklist is a great way to structure both exam preparation and refresher training ahead of renewal.

Helicopter vs Aeroplane: Key Differences

The licence framework treats helicopters and aeroplanes as separate worlds, and you must choose your side early:

• Modules: aeroplane categories study M11 (aeroplane aerodynamics, structures and systems), while helicopter categories study M12 (helicopter aerodynamics, structures and systems) — including rotor systems, main gearboxes and flight controls unique to rotorcraft
• Engines: both worlds use M15 (gas turbine) and M16 (piston), but helicopter engineers go deeper into free-turbine arrangements and drive-train interfaces
• Category split: B1.1/B1.2 = aeroplanes, B1.3/B1.4 = helicopters, B2 covers both, B3 covers light helicopters and small aeroplanes
• Type ratings: helicopter type ratings (e.g. Airbus H125, Leonardo AW139, Robinson R44) are distinct from aeroplane ratings and require separate type training

If you are not sure which world suits you, talk to engineers in both fields before committing — the module sets and career paths diverge from day one.

Licence Conversion and Mutual Recognition

One of the great strengths of the Part-66 system is its portability:

• Mutual recognition: a licence issued by one EASA member state is valid in all member states — no conversion needed to work in another country
• Category upgrades: adding a category (e.g. A → B1.2, or B1.2 → B1.1) requires passing the additional module examinations and meeting the category's experience requirement
• Third-country conversions: authorities may convert licences issued outside the EASA system based on an assessment of equivalent training and experience, often requiring additional "difference" training and examinations
• Documentation: keep your licence, logbook and training certificates in order — you will need them for every application, upgrade and renewal

Career Outlook and Salary Expectations

The demand for licensed certifying staff in Europe is strong and projected to grow. An ageing workforce combined with record air travel demand means airlines, MROs, helicopter operators and general aviation companies are actively recruiting licensed engineers. Industry forecasts estimate tens of thousands of new maintenance professionals will be needed across Europe over the next decade.

Salary by experience level (indicative, varies by country and operator):

• Apprentice / Entry-level: €24,000–€32,000
• Licensed B1/B2 (3–5 years): €40,000–€55,000
• Senior / Lead certifying staff: €60,000–€75,000
• Base maintenance release (Category C) with type ratings: €75,000–€90,000+

Many employers also offer shift premiums, overtime, travel allowances and pension schemes. The licence also offers excellent mobility — certified engineers work across the continent and beyond, thanks to the mutual recognition built into the European system. Interested in the numbers for your country? Contact us and we will point you to the right resources.

External Resources

For official information straight from the regulator, consult these authoritative resources:

• EASA — Part-66 (Aircraft Maintenance Licence) — Official EASA hub for the Aircraft Maintenance Licence, categories and requirements
• Regulation (EU) No 1321/2014 — consolidated text — Full text of the regulation containing Annex III (Part-66) with Appendices I and II
• EASA Regulations Library — Part-66, AMC/GM guidance and all related aviation safety regulations
• EASA — Aircraft Products & Maintenance — Overview of the regulatory framework for aircraft maintenance in Europe

Frequently Asked Questions

Can I hold more than one licence category?

Yes — and many engineers do. You can hold Category A alongside B1 or B2, or hold multiple B1 subcategories (e.g. B1.1 and B1.2). Each additional category requires passing the extra module examinations and meeting its experience requirement. Holding several categories makes you more versatile and more valuable to employers.

How long are the module examination results valid?

Module examinations must be passed within 10 years of your licence application (66.A.25). If a pass is older, you can request examination credit from your competent authority under Subpart E of Part-66 — authorities may credit older passes based on your training and experience.

Is there a difference between AME, certifying staff and aircraft maintenance engineer?

In Europe, the official term is Aircraft Maintenance Engineer (AME) holding the Part-66 Aircraft Maintenance Licence. The operational term used by the regulation is certifying staff — the person authorised to certify maintenance and release aircraft to service. The terms are used interchangeably in the industry.

What happens if I fail a module examination?

You can retake any failed module examination. You must wait at least 30 days before retaking the same module, and you get a maximum of 3 consecutive attempts per module before a 1-year waiting period applies. Use the waiting period to focus on your weak areas — Skylicence Europe's adaptive question bank helps you target exactly the topics where you need improvement.

Do I need a university degree to become licensed?

No. There is no degree requirement for the Part-66 Aircraft Maintenance Licence. The MTO school route is the most structured and efficient path and folds the experience requirement into the program, but you can qualify entirely through documented on-the-job experience — provided you also pass every module examination of your category.

How Skylicence Europe Prepares You for Success

Skylicence Europe is the AI-powered study platform built specifically for the EASA Part-66 module examinations. Unlike generic flashcard apps or outdated question banks, our platform intelligently adapts to your learning needs:

• Full Appendix I coverage — Every module (M1–M17) and knowledge level (1/2/3) mapped to practice questions and detailed explanations
• Category-accurate simulations — Question counts and time limits per module per category, straight from Appendix II, including the essay questions on M7, M9 and M10
• Adaptive difficulty engine — The AI identifies your weak areas and adjusts question difficulty in real time
• Timed exam simulations — Replicate the real Part-66 testing environment with the 75% pass mark built into every practice run
• AI Tutor — Get instant, plain-language explanations of complex regulatory and technical topics
• Comprehensive analytics — Track your progress across every module, subject area and learning objective

Start your EASA Part-66 journey with Skylicence Europe today →