EASA Part-66 Module Syllabus Guide: Complete Breakdown

1. Introduction to the Part-66 Module System

The Part-66 module system, published as Appendix I of Annex III to Regulation (EU) No 1321/2014, is the authoritative framework for the basic knowledge of all aircraft maintenance licences in Europe. It replaced the older national licensing syllabuses and introduced a harmonised, module-based structure aligned with how EASA actually examines engineers — through computer-based module exams at approved maintenance training organisations (MTOs). Whether you are pursuing a B1.1 aeroplane turbine licence, a B2 avionics licence, or any other category, the knowledge requirements defined in Appendix I form the foundation of your examination journey.

Understanding the module system is critical because MTOs design every exam question to test specific elements within this document. If you know the structure, you know exactly what to study — and more importantly, what not to waste time on. The syllabus eliminates guesswork from your preparation strategy.

The system is organised into 17 modules —M1 to M17 — each containing subject areas with defined depth levels. Each subject is assigned a depth level:1 (overview), 2 (detailed), or 3 (in-depth), and the level required depends on your licence category — B category licences demand the deeper levels. The framework also includes the certification prerequisites (18 years old, the experience requirements of 66.A.30 documented in a logbook, and the basic knowledge requirements of 66.A.25, including the 75% pass mark) and references the regulatory framework of Regulation (EU) No 1321/2014 — Part-66, Part-145, Part-M and the training organisation rules.

For a broader overview of the licensing process, including how the modules fit into the bigger picture, see our guide on how to become a Part-66 engineer in Europe.

2. Foundation and General Modules (M1–M10)

The foundation modules are the core of the licence. They cover the knowledge and skills every engineer needs regardless of category. Each module has a set question quota and time limit — for example M3 Electrical Fundamentals has 92 questions in 115 minutes, and M7 Maintenance Practices has 140 questions in 175 minutes. A score of 75% is required to pass every module. The foundation material also appears throughout the technical modules, so mastering M1–M10 pays off across all your exams.

Modules in this group include:

• M1 Mathematics: Arithmetic, algebra, geometry, and the calculations used in maintenance — ratios, percentages, areas, volumes, and temperature conversions. Weight & balance maths appears in this module and again in the airframe modules. 32 questions in 40 minutes.
• M2 Physics: Force, work, power, energy, simple machines, and fluid mechanics. Understanding how levers, gears, pulleys, and hydraulic systems behave is essential for both the exam and the hangar. 52 questions in 65 minutes.
• M3 Electrical Fundamentals: Ohm's law, Kirchhoff's laws, AC/DC theory, inductance, capacitance, impedance, and power calculations. Series and parallel circuits, voltage dividers, and the effects of temperature on components. 92 questions in 115 minutes.
• M4 Electronic Fundamentals: Semiconductors, diodes, transistors, thyristors, and integrated circuits — the electronic building blocks behind modern aircraft systems. 72 questions in 90 minutes.
• M5 Digital Techniques / Electronic Instrument Systems: Logic gates, flip-flops, microprocessors, data buses, and electronic displays (EFIS, ECAM/EICAS, flight data recording). 92 questions in 115 minutes.
• M6 Materials and Hardware: Aircraft metals (aluminium alloys, steels, titanium), composites, wood, and fabric. Heat treatment, hardness testing, corrosion types, fasteners, and the properties that determine material selection. 72 questions in 90 minutes.
• M7 Maintenance Practices: The largest module: safety, workshop practices, tools, measurements, inspection techniques (including NDT), riveting, welding, bearings, transmissions, and documentation. 140 questions in 175 minutes.
• M8 Basic Aerodynamics: The physics of flight — lift, drag, thrust, weight, aerofoil theory, stability, and the atmosphere. 42 questions in 55 minutes.
• M9 Human Factors: The physiological and psychological factors that affect maintenance performance — the Dirty Dozen, SHELL model, fatigue, stress, communication, and error prevention. 34 questions in 45 minutes.
• M10 Aviation Legislation: One of the most heavily tested areas. Regulation (EU) No 1321/2014, Part-66 licensing (categories, privileges, experience), Part-145 organisations, Part-M/CAMO, the Certificate of Release to Service, EASA Form 1, and Airworthiness Directives. 64 questions in 80 minutes.

The foundation group is often considered one of the most challenging because it requires precise knowledge across a very broad range of topics — from regulatory language to physics calculations. EASA expects you to know not just the general concept but the specific requirements, including references and conditions. For a dedicated deep dive into the legislation portion, read our complete aviation legislation guide.

3. Airframe Modules (M11, M12, M13)

The airframe modules cover the structures, systems, and components that make up the aircraft. Module 11 (Aeroplane Aerodynamics, Structures and Systems) is required for B1.1 and B1.2 candidates with 120 questions in 150 minutes. Module 12 (Helicopter Aerodynamics, Structures and Systems) replaces it for B1.3 and B1.4 candidates with 90 questions in 115 minutes. Module 13 (Aircraft Aerodynamics, Structures and Systems) covers the systems-level knowledge required for B2 avionics candidates with 120 questions in 150 minutes.

Subject areas in the airframe modules include:

• Aeroplane/Helicopter Aerodynamics: The theory of flight, aerofoil behaviour, stability, and control — building on Module 8.
• Airframe Structures: Fuselage, wings, stabilisers, and landing gear attachments. Sheet metal layout, forming, riveting, and fasteners. Composite structures including fibreglass and carbon fibre repair, bonding, and inspection. This is a heavily tested area.
• Airframe Assembly and Rigging: Aircraft assembly, alignment, flight control rigging, and symmetry checks. Cable tensioning and control travel verification.
• Airframe Inspection: The scope and methods of airframe inspections, NDT methods (dye penetrant, magnetic particle, eddy current, ultrasonic, radiographic), and corrosion inspections.
• Aircraft Electrical Systems: Aircraft wiring, connectors, circuit protection, bonding and grounding, and electrical load analysis. Wiring inspection and repair standards.
• Aircraft Instrument Systems: Pitot-static systems, gyroscopic instruments, electronic flight instruments, and instrument system testing.
• Communication and Navigation Systems: VHF, HF, VOR, ILS, DME, ADF, GPS, transponders, and weather radar. Installation and testing of avionics equipment.
• Hydraulic and Pneumatic Power Systems: Hydraulic pumps, actuators, valves, accumulators, filters, and fluids. Pneumatic systems including bleed air and pressurisation.
• Landing Gear Systems: Fixed and retractable gear, shock absorption (oleo-pneumatic struts), brakes, wheels, tyres, anti-skid systems, and nosewheel steering.
• Aircraft Fuel Systems: Fuel tanks, pumps, valves, vents, fuel quantity indicating systems, fuel management, and fuelling procedures.
• Environmental Systems: Cabin pressurisation, air conditioning, heating, and oxygen systems — both crew and passenger.
• Aircraft Fire Protection Systems: Fire detection and extinguishing systems, smoke detection, and the maintenance of fire protection equipment.
• Ice and Rain Control Systems: Pneumatic de-icing boots, electro-thermal anti-icing, windshield ice protection, and rain removal systems.
• Flight Control Systems: Primary and secondary flight controls, actuation systems (cable, push-pull, hydraulic, fly-by-wire), trim systems, and control surface balancing.

The airframe modules require both theoretical knowledge of how systems work and practical knowledge of how to inspect, troubleshoot, and maintain them. This is where hands-on experience from your apprenticeship or MTO training becomes invaluable.

4. Propulsion Modules (M14, M15, M16, M17)

The propulsion modules cover aircraft engines — both piston and turbine — plus propellers. Module 14 (Propulsion) provides the core overview for all B1 categories with 60 questions in 75 minutes. Module 15 (Gas Turbine Engine) covers turbine engines in depth with 108 questions in 135 minutes. Module 16 (Piston Engine) covers reciprocating engines with 60 questions in 75 minutes, and Module 17 (Propeller) covers propeller systems with 48 questions in 60 minutes. B1.1 candidates must master Module 15 in depth; B1.2 candidates master Module 16.

Subject areas in the propulsion modules include:

• Propulsion Fundamentals (M14): Engine types, engine performance, engine construction overview, and the relationship between engines and aircraft systems.
• Gas Turbine Engines (M15): Gas turbine cycle (Brayton cycle), engine types (turbojet, turbofan, turboprop, turboshaft), compressor types (axial, centrifugal), combustion chambers, turbine sections, and exhaust systems. Thrust production and the factors affecting it.
• Piston Engines (M16): Four-stroke cycle theory, engine configurations (horizontally opposed, radial, inline), valve timing, ignition timing, and power output. Cylinder, piston, crankshaft, and valvetrain components.
• Engine Inspection: Piston and turbine engine inspection procedures, compression testing, borescope inspection, and engine condition monitoring.
• Engine Instrument Systems: RPM (tachometer), oil pressure and temperature, cylinder head temperature, exhaust gas temperature, torque, fuel flow, and engine vibration monitoring. Normal operating ranges and exceedance handling.
• Engine Fire Protection Systems: Fire detection and extinguishing systems specific to the engine installation.
• Engine Electrical Systems: Starting systems, ignition systems (magnetos, igniters), electrical components, and wiring on the engine installation.
• Lubrication Systems: Wet sump and dry sump systems, oil types, filters, coolers, and oil analysis. Lubrication system troubleshooting.
• Ignition and Starting Systems: Magnetos, ignition harnesses, igniter plugs, timing procedures, and starter systems (electric, pneumatic, and turbine starters).
• Fuel Metering Systems: Carburettors, fuel injection systems, fuel control units, and the principles of fuel metering in both piston and turbine engines.
• Engine Fuel Systems: Fuel types, fuel system components (pumps, filters, valves, fuel control units), and fuel system maintenance procedures.
• Induction Systems: Air induction, carburettor heat, alternate air, and the effects of induction icing.
• Engine Cooling Systems: Air-cooled design (fins, baffles, cowl flaps) and liquid-cooled systems. Cooling system maintenance and inspection.
• Engine Exhaust Systems: Exhaust manifolds, turbochargers, wastegates, and exhaust system inspection for leaks and cracks.
• Propellers (M17): Fixed-pitch and constant-speed propellers, feathering and reversing, propeller governors, synchronisation, and ice protection. Propeller tracking, balancing, and hub inspection.

The propulsion modules benefit greatly from the use of visual study aids and practical examples. Understanding the difference between a carburetted engine and a fuel-injected engine, or between a centrifugal compressor and an axial compressor, requires both memorisation and conceptual understanding. The Skylicence Europe AI Tutor is particularly helpful here, as you can ask for plain-language explanations of complex thermodynamic and mechanical concepts.

5. Study Strategies for the Module Exams

Mastering the Part-66 module system requires a structured approach. Here are proven strategies used by successful Part-66 candidates:

1. Map the Syllabus to Your Study Plan

Start by downloading the Part-66 Appendix I syllabus for your category. For each module, list every subject area and rate your current knowledge level (None, Basic, Proficient, Expert). This creates a personalised study roadmap and highlights exactly where to focus your effort. Most candidates find they have 2–3 strong modules and several weaker ones — invest your time proportionally.

2. Use Active Recall with Practice Questions

Reading textbooks is passive. Active recall — testing yourself with practice questions — is proven to be dramatically more effective for long-term retention. This is where Skylicence Europe excels. With 4,464 questions mapped to every module syllabus, you can test yourself repeatedly until the knowledge sticks. The AI-powered adaptive difficulty ensures you are always challenged at the right level.

3. Study in Module-Specific Blocks

Rather than mixing modules in a single study session, focus on one module at a time. Each module has its own logical structure and vocabulary. Studying them separately prevents confusion and helps you build deep knowledge in each area. Once you have mastered individual modules, take comprehensive practice exams that mix questions across the syllabus — exactly like the real module exams do.

4. Leverage AI-Powered Study Tools

Modern AI tools can dramatically accelerate your exam preparation. Platforms like Skylicence Europe use adaptive algorithms that identify your weak areas and generate targeted practice questions. The AI Tutor feature lets you ask natural-language questions about complex topics — like "explain how a constant-speed propeller governor works" or "what is the difference between the CRS and the EASA Form 1?" — and receive instant, exam-focused answers.

5. Simulate Exam Conditions

Practise under real exam conditions: timed, with no interruptions, in a quiet environment. The actual module exams are computer-based at approved MTOs with strict time limits per module — for example, 92 questions in 115 minutes for Module 3. If you have only practised in a relaxed, untimed setting, you may be shocked by the time pressure on exam day. Skylicence Europe's exam simulation mode replicates the exact format, timing, and difficulty of the real exams, so you walk in fully prepared.

6. Review and Iterate

After each practice session, review every question you got wrong. Understandwhy the correct answer is correct and why your choice was wrong. This is far more valuable than simply reading the correct answer. Use the detailed explanations in Skylicence Europe to trace your mistake back to the specific syllabus subject, then revisit that topic. Over time, your accuracy will improve as you close knowledge gaps systematically.

6. Frequently Asked Questions

Master the Part-66 Syllabus with Skylicence Europe

The Part-66 module system is your roadmap to an aircraft maintenance licence in Europe. By understanding its structure — 17 modules with specific subject areas and depth levels — you can study with precision and confidence. Whether you are pursuing a B1.1 licence, a B2 avionics licence, or any other category, every minute spent mastering the syllabus is an investment in your career as an aircraft maintenance professional.

Skylicence Europe was built specifically to help you navigate and master this syllabus. With 4,464 practice questions across all 17 modules, adaptive AI difficulty, real exam simulations, and an AI Tutor that explains any concept in plain language, you have everything you need to pass your exams on the first attempt.

Start Studying with Skylicence Europe →