EASA Part-66 Licence Categories: B1 vs B2 vs A vs B3

Understanding the Part-66 Licence Categories

Before diving into the comparison, it is important to understand the foundational structure. The EASA Part-66 licence, issued under Regulation (EU) No 1321/2014, Annex III, defines 8 licence categories: A (line maintenance), B1.1 (aeroplane turbine), B1.2 (aeroplane piston), B1.3 (helicopter turbine), B1.4 (helicopter piston), B2 (avionics), B3 (non-pressurised piston helicopters), plus the A category. Each category authorises you to certify maintenance in a specific domain, and each maps to its own subset of the 17 basic-knowledge modules (Part-66 Appendix I).

If you have not yet read our complete guide to becoming an EASA Part-66 licensed engineer in Europe, start there for the overall process and eligibility requirements. This guide assumes you understand the basics and focuses specifically on helping you choose between the main licence categories.

Category B1 (Mechanical)

The B1 licence is the most common aircraft maintenance credential in Europe. It covers the mechanical, structural, and powerplant systems of an aircraft — essentially the airframe (fuselage, wings, landing gear, flight controls, hydraulics) and the propulsion installation (engines, propellers, fuel systems, lubrication). The B1 licence is issued in four subcategories: B1.1 (aeroplane turbine), B1.2 (aeroplane piston), B1.3 (helicopter turbine), and B1.4 (helicopter piston). We cover the subcategories in detail in our B1 vs B2 licence guide.

Scope: B1 engineers perform and certify inspections, repairs, modifications, and component replacements on airframes and engines. This includes sheet metal repair, composite repair, engine removal and installation, landing gear overhaul, flight control rigging, hydraulic system troubleshooting, and corrosion prevention. If it involves structure, mechanics, or propulsion, it falls under the B1 licence.

Exams and requirements: B1 candidates must pass the module exams for their subcategory (13 modules for B1.1, covering M1-M10 plus M11, M14, M15 and M17) with a 75% pass mark, complete 5 years of experience (3 with a recognised technical diploma), and pass the assessment of competence (66.A.40).

Difficulty: The B1 syllabus is broad — the breadth of topics is wide, but the depth required in any single area is generally manageable. The propulsion modules (M15 Gas Turbine Engine, M16 Piston Engine, M17 Propeller) are often reported as the most challenging, requiring strong understanding of both engine theory and systems.

Career paths: B1 engineers work at major airlines (Lufthansa, Air France-KLM, Ryanair, easyJet), MROs (Lufthansa Technik, SR Technics, AFI KLM E&M, Sabena technics), regional carriers, general aviation shops, flight schools, corporate flight departments, and OEM service centres (Airbus, Boeing, Leonardo, Dassault).

Salary expectations: B1 salaries range widely by country and employer. Entry-level licensed engineers earn €30,000–€45,000 per year. Experienced engineers at major airlines and MROs earn €45,000–€65,000, and leads, type-rated engineers, and specialists at majors can reach €70,000–€100,000+ with overtime and premiums.

Industry demand: The B1 licence has the highest demand of all categories. The majority of aircraft maintenance tasks involve mechanical and structural work, and the European industry reports a sustained shortage of licensed B1 engineers.

Category B2 (Avionics)

The B2 licence covers avionics — the electrical and electronic systems of modern aircraft: communication radios, navigation systems, instruments, radar, autopilots, flight management computers, and digital data networks. B2 is the electronics specialist's licence, and it is governed by the same Part-66 framework (66.A.20-66.A.100).

Scope: A B2 engineer may certify work on all electrical and electronic systems, including power generation and distribution, instruments, communication and navigation, autoflight, and integrated modular avionics. The B2 syllabus replaces the mechanical modules with the electronics-heavy set: M4 Electronic Fundamentals, M5 Digital Techniques/Electronic Instrument Systems, and M13 Aircraft Aerodynamics Structures and Systems instead of the aeroplane-specific M11/M14/M15/M17 set.

Requirements: Like B1.1, B2 requires 5 years of experience (3 with a recognised technical diploma, 2 with a recognised technician licence), the B2 module set with a 75% pass mark, and the assessment of competence.

Difficulty: The B2 exams are considered demanding — electronic and digital theory requires both memorisation and conceptual understanding. Candidates with strong backgrounds in electronics and digital techniques tend to find the B2 syllabus more natural.

Career paths: B2 engineers work at airline avionics bays, avionics shops, MRO avionics divisions, and OEMs. With aircraft becoming increasingly computerised — fly-by-wire, integrated modular avionics, connected aircraft — demand for B2 engineers continues to grow.

Salary expectations: B2 salaries track B1 levels closely — typically €30,000–€65,000 depending on country and employer, with type-rated B2 engineers at major airlines earning at the top of the range.

Industry demand: Demand for B2 engineers is strong and growing, driven by the electronics content of modern aircraft fleets.

Category A (Line Maintenance)

Category A is a limited line maintenance licence: it authorises the holder to perform and certify a predefined list of line maintenance tasks — typically inspections, servicing, and simple component replacements — under the supervision of B1 or B2 certifying staff. The A licence requires 2 years of experience and a smaller module set, making it the fastest route into certifying work for line operations.

Scope: The tasks an A licence holder may certify are defined by the organisation's procedures (Part-145); they are limited to line maintenance tasks on the ground. A licence holders cannot certify base maintenance or complex repairs.

Requirements: 2 years of practical experience, the A-category module set, and a 75% pass mark on each module. Many A licence holders later extend their licence to B1 or B2 by passing the additional modules and completing the extra experience.

Career paths: A licence holders work in airline line stations, MRO line operations, and general aviation line maintenance. The A licence is an excellent first step into certifying staff roles while building toward a B category.

Category B3 (Non-Pressurised Piston Helicopters)

The B3 licence is a combined mechanical/avionics licence limited to small, non-pressurised piston helicopters — the training and light helicopter sector (Robinson, Airbus Helicopters H120/H125-class, Enstrom, and similar). B3 engineers may certify both mechanical and electrical work on these types, within the limits of the B3 privileges.

Requirements: 2 years of practical experience, the B3 module set, and a 75% pass mark on each module. The B3 syllabus includes modules from both the B1 and B2 worlds, tailored to small piston helicopters.

Career paths: B3 engineers work at helicopter training schools, light helicopter operators, and general aviation helicopter shops — a niche but steadily demanded skill set.

Side-by-Side Comparison Table

Which Licence Should You Start With?

Choosing your first licence category is a significant career decision. Here are the key factors to consider:

Start with B1 if:

• You want the broadest career options. B1 is the most versatile and in highest demand. It opens doors at airlines, MROs, flight schools, and everywhere in between.
• You enjoy working with your hands on mechanical systems. If the idea of overhauling an engine, rigging flight controls, or repairing landing gear excites you, B1 is the right path.
• You are unsure about your specialisation. B1 covers the widest range of topics, giving you exposure to many different areas before you decide to specialise.

Choose B2 if:

• You have a strong interest in electronics and digital systems. The B2 syllabus is built around M3-M5 and M13, not the mechanical modules.
• You enjoy diagnostic, precision work — bench testing, wiring, software loading, and system troubleshooting.
• You want to specialise in the fastest-growing area of maintenance. Modern aircraft carry exponentially more electronics, and B2 demand is rising with it.

Choose A or B3 if:

• You want to start certifying work quickly. Category A requires only 2 years of experience and is the fastest route into line maintenance certification.
• You are heading for the light helicopter sector. B3 is the dedicated licence for small non-pressurised piston helicopters, combining mechanical and avionics privileges.
• You plan to build up over time. Many engineers start with A and extend to B1 or B2 later, adding modules as their career evolves.

Can You Hold Multiple Categories?

Yes — Part-66 licences are designed to stack. You can hold B1 and B2 on a single licence, and many employers value the "dual" B1/B2 engineer extremely highly. You can also hold a B1 subcategory alongside a B3. Each additional category requires passing its module set and meeting its experience requirements — but the fundamentals modules (M1-M10) are shared across categories, so the marginal cost of an additional category is significantly lower than the first.

The typical path to multiple categories is:

1. Earn your first category (module exams + experience + assessment of competence)
2. Work for 2-5 years gaining practical experience in that category
3. Pass the additional modules for the next category (credits from shared modules transfer)
4. Complete the additional experience and assessment of competence
5. Request the extension from your national aviation authority, which updates the licence

Skylicence Europe covers the module exams for all 8 licence categories — making it the ideal platform for earning your first category and building the foundation for extensions later in your career.

Regulation (EU) No 1321/2014 and the Regulatory Framework

The regulatory basis for all licence categories is Regulation (EU) No 1321/2014 — Annex III (Part-66) governs the licence, Annex II (Part-145) governs maintenance organisations, and Annex I (Part-M) with its CAMO provisions governs continuing airworthiness. The framework is evolving: Regulation (EU) 2023/989 is reshaping the organisation rules, but the Part-66 licence structure — categories, modules, experience, and the 75% pass mark — remains the foundation of engineer certification in Europe. That is why M10 Aviation Legislation appears in every category's module set.

For a complete breakdown of the legislation module, including key topics and study strategies, read our EASA Part-66 module exams guide.

How Skylicence Europe Covers Part-66 Preparation

Skylicence Europe provides comprehensive AI-powered exam preparation for the Part-66 module exams — 4,464 questions mapped to all 17 modules (Appendix I) and all 8 licence categories. Our adaptive learning algorithms identify your weak areas and generate targeted practice questions.

Whether you are pursuing your first B1.1 licence or adding a B2 category to an existing licence, Skylicence Europe adapts to your specific needs. The AI Tutor can explain complex concepts — from gas turbine theory to digital data buses to 66.A.25 examination rules — in clear, exam-focused language. Progress tracking shows your performance across every module, so you always know exactly where you stand and what needs more work.

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Summary: Making Your Decision

There is no universally "right" category — the best choice depends on your interests, aptitudes, and career goals. B1 offers the broadest opportunities and highest overall demand. B2 offers the specialist electronics path with the strongest growth outlook. A offers the fastest entry into certifying line work, and B3 serves the light helicopter niche.

If you are still unsure, consider starting with B1.1 — the most versatile foundation — and remember you can always add categories later as your career interests crystallise. Whichever path you choose, the key to success is thorough exam preparation — and Skylicence Europe is built to help you achieve that.

For more background on the Part-66 certification process, eligibility, and training pathways, read our complete guide to becoming an EASA Part-66 licensed engineer.