Which EASA Part 66 modules do you need?

Part-66 does not ask every candidate to sit every module. What you need depends entirely on the licence category you are working towards — and the difference is substantial: a B2 avionics candidate never sits the gas turbine module, while a B1.1 candidate never sits the avionics systems module. Picking the wrong ones is an expensive mistake, because exam fees and study time are not refundable.

This page lists the module requirements for every category, and links each one to its question bank so you can see what the content actually looks like before you commit.

Module requirements by category

The fundamentals from Mathematics through Aviation Legislation are common to every category (category A skips Module 4, Electronic Fundamentals). What changes is the airframe/systems module and the powerplant modules on the end.

The ten modules (almost) everybody sits

Whatever category you are heading for, these are on your list (category A leaves out Module 4). They are also the ones most people sit first, because the later systems modules assume them.

• Module 1 — Mathematics. The numerical foundation every aircraft maintenance engineer relies on — arithmetic, algebra and geometry.
• Module 2 — Physics. The physical principles behind how aircraft and their systems behave — matter, mechanics, heat, light and sound.
• Module 3 — Electrical Fundamentals. A thorough grounding in DC and AC electrical theory — from electron flow, resistance and capacitance to transformers, generators and motors.
• Module 4 — Electronic Fundamentals. The building blocks of aircraft electronics: semiconductors, printed circuit boards and servomechanisms.
• Module 5 — Digital Techniques / Electronic Instrument Systems. Digital and computer-based systems and the electronic instruments they drive — logic circuits, data buses, microprocessors, displays and fibre optics.
• Module 6 — Materials and Hardware. What aircraft are built from and the hardware that holds them together — metals, composites, corrosion, fasteners, bearings and cables.
• Module 7 — Maintenance Practices. The most hands-on of the certifying modules — the workshop, hangar and flight-line skills that turn theory into practice.
• Module 8 — Basic Aerodynamics. Why aircraft fly — the atmosphere, aerodynamics, theory of flight and flight stability.
• Module 9 — Human Factors. How people — not just machines — affect safe maintenance: performance and limitations, communication, human error and workplace hazards.
• Module 10 — Aviation Legislation. The regulatory framework that governs licences, maintenance organisations and airworthiness — Part-66, Part-145, continuing airworthiness and certification.

Where the paths split

After Module 10, the categories diverge — and this is the part worth getting right before you book anything.

Aeroplane mechanical (A1/A2, B1.1/B1.2)

You take the aeroplane systems module (Module 11), a powerplant module matched to the engine type — Module 15 (Gas Turbine) for turbine, Module 16 (Piston) for piston — and Module 17 (Propeller).

Electric aeroplanes (B1.E)

New from 13 February 2026, for aeroplanes with an electric power plant and a maximum take-off mass below 5,700 kg. You take Module 11, Module 17 (Propeller) and the new Module 18 (Electric Power Plant): batteries, fuel cells, power distribution and electronic engine control, examined in 76 questions over 95 minutes. Read the B1.E guide.

Helicopter mechanical (A3/A4, B1.3/B1.4)

You take Module 12 (Helicopter Aerodynamics, Structures and Systems) instead of Module 11, plus the powerplant module for your engine type. There is no propeller module on the helicopter path.

Avionics (B2)

B2 is the one path that does not touch Modules 11, 12, 15, 16 or 17 at all. Instead you sit Module 13 (Aircraft Aerodynamics, Structures and Systems) — the largest single module in the whole licence — and Module 14 (Propulsion), which covers engines from an instrumentation and control perspective rather than a strip-down one.

Category A and B1 sit almost the same modules — but not the same exams

This catches people out. Look at the table and A1 and B1.1 look nearly identical: apart from Module 4, which category A does not sit, the modules are the same. The difference is the knowledge level each module is examined at.

Part-66 defines three levels: Level 1 is a general familiarisation, Level 2 is a general knowledge with some practical application, and Level 3 is a detailed working knowledge you could troubleshoot from. Category A modules are largely examined at Levels 1 and 2. The same module for B1 is examined at Level 2 or 3 — more questions, more depth, and significantly more time allowed.

The practical consequence: an A-licence pass does not automatically carry over as a B1 pass for the same module. If you think you may go for B1 later, many candidates study to the B1 level from the start rather than sit the same subject twice.

So how many exams is that?

Thirteen modules for B1.1, B1.2 and B1.E, twelve for B1.3, B1.4 and B2, thirteen for B3, and twelve or eleven for category A. Module 7 also has two essay questions for every category in addition to the multiple-choice paper, so the number of exam sittings can be higher than the module count suggests. Modules 9 and 10 used to as well, but both became multiple-choice only in June 2024.

There is no fixed order and no requirement to sit them all at one organisation, so most candidates spread them across a couple of years. What most people do is start with Modules 1, 2 and 3, because almost everything later leans on them.