Part-66 Modules 1 to 17: The Complete Guide

The Part-66 syllabus is split into 17 modules, and every aircraft maintenance licence category needs its own set of them. (Since 13 February 2026 the EU syllabus also has a Module 18 on electric power plants, for the new B1.E subcategory under Regulation (EU) 2025/111; this guide and our question bank cover Modules 1 to 17.) This guide lists every module, what it covers, which categories sit it, and how long each paper is under EASA and UK CAA rules, so you can plan your exams module by module. Each module links to a page of practice questions and a free exam-style paper sized for your category.

Part-66 Prep is an independent study aid. We are not EASA, the UK CAA or a Part-147 organisation, and nothing here replaces your training or the official rules. For the rule text, the syllabus is Appendix I and the exam standard is Appendix II to Part-66, in Regulation (EU) No 1321/2014 for the EU and in UK Part-66 for the UK.

The 17 Part-66 modules at a glance

Modules 1 to 10 are the foundation and almost every category sits them. Modules 11 to 17 are about a type of aircraft or engine, so you only sit the ones that match your licence.

Module	Title	Who sits it	Practice
1	Mathematics	All categories	Module 1 questions
2	Physics	All categories	Module 2 questions
3	Electrical fundamentals	All categories	Module 3 questions
4	Electronic fundamentals	B1, B2, B2L, B3 (not A)	Module 4 questions
5	Digital techniques and electronic instrument systems	All categories	Module 5 questions
6	Materials and hardware	All categories	Module 6 questions
7	Maintenance practices	All categories (UK: 7A, or 7B for B3)	Module 7 questions
8	Basic aerodynamics	All categories	Module 8 questions
9	Human factors	All categories (UK: 9A, or 9B for B3)	Module 9 questions
10	Aviation legislation	All categories	Module 10 questions
11A / 11B / 11C	Aeroplane aerodynamics, structures and systems (turbine, piston, B3)	A1, B1.1 / A2, B1.2 / B3	Module 11 questions
12	Helicopter aerodynamics, structures and systems	A3, A4, B1.3, B1.4	Module 12 questions
13	Aircraft aerodynamics, structures and systems	B2, B2L	Module 13 questions
14	Propulsion	B2, B2L	Module 14 questions
15	Gas turbine engine	A1, A3, B1.1, B1.3	Module 15 questions
16	Piston engine	A2, A4, B1.2, B1.4, B3	Module 16 questions
17A / 17B	Propeller (17B for B3)	A1, A2, B1.1, B1.2 / B3	Module 17 questions

Key fact: Category A has four subcategories (A1 turbine aeroplanes, A2 piston aeroplanes, A3 turbine helicopters, A4 piston helicopters) and B1 has four (B1.1 to B1.4). This site covers A as one category with every A module, and B1.1, B1.2 and B1.3; B1.4 (piston helicopters) uses the same modules as B1.3 with Module 16 in place of 15.

Which modules each licence category sits

Your category decides your list of papers. These are the module papers each category sits on this site, matching the modularisation table in Appendix I.

Category	Module papers	Number of papers
A (all subcategories)	1, 2, 3, 5, 6, 7, 8, 9, 10, plus 11A, 11B or 12, 15 or 16, and 17A for aeroplanes	11 to 12 for one subcategory
B1.1 turbine aeroplanes	1–10, 11A, 15, 17A	13
B1.2 piston aeroplanes	1–10, 11B, 16, 17A	13
B1.3 turbine helicopters	1–10, 12, 15	12
B2 avionics	1–10, 13, 14	12
B2L avionics with system ratings	1–10, 13, 14 (13 per rating)	12
B3 piston aeroplanes up to 2,000 kg	1–10, 11C, 16, 17B	13

If you already hold one category and want another, you sit only the modules or the higher-level papers you are missing. For example, a B1.1 engineer adding B2 typically needs Module 13 and Module 14 and the B2-level versions of the shared modules where the B2 paper differs, such as Module 4 (40 questions for B2 against 20 for B1) and Module 5 (72 against 40). The licence categories guide explains each category's privileges in full.

Question counts and times for every module

Every module exam uses three-option multiple-choice questions with about 75 seconds allowed per question, so the time follows from the number of questions. The table shows the EASA figures under Regulation (EU) 2023/989, which has applied since 12 June 2024, as questions and minutes.

Module	A	B1	B2 / B2L	B3
1 Mathematics	16 / 20	32 / 40	32 / 40	32 / 40
2 Physics	32 / 40	52 / 65	52 / 65	32 / 40
3 Electrical fundamentals	20 / 25	52 / 65	52 / 65	24 / 30
4 Electronic fundamentals	–	20 / 25	40 / 50	20 / 25
5 Digital techniques	20 / 25	40 / 50	72 / 90	20 / 25
6 Materials and hardware	52 / 65	80 / 100	60 / 75	80 / 100
7 Maintenance practices	76 / 95 + 2 essays	80 / 100 + 2 essays	60 / 75 + 2 essays	80 / 100 + 2 essays
8 Basic aerodynamics	24 / 30	24 / 30	24 / 30	24 / 30
9 Human factors	28 / 35	28 / 35	28 / 35	28 / 35
10 Aviation legislation	32 / 40	44 / 55	44 / 55	44 / 55
11A / 11B / 11C	108 / 135 (11A), 72 / 90 (11B)	140 / 175 (11A), 100 / 125 (11B)	–	60 / 75 (11C)
12 Helicopters	100 / 125	128 / 160	–	–
13 Aircraft systems	–	–	188 / 235	–
14 Propulsion	–	–	32 / 40	–
15 Gas turbine engine	60 / 75	92 / 115	–	–
16 Piston engine	52 / 65	76 / 95	–	76 / 95
17A / 17B Propeller	20 / 25	32 / 40	–	32 / 40

Essays are 20 minutes each, on top of the multiple-choice time. Under EASA rules a paper longer than 90 minutes may be split into two partial exams, and one longer than 180 minutes into three, as long as each part is passed and taken at the same organisation.

Where UK CAA papers differ

The UK kept the earlier version of Appendix II, so several UK papers are shorter and three modules carry essays. These are the differences that matter most:

Module	EASA	UK CAA
8 Basic aerodynamics (all categories)	24 questions	20 questions
9 Human factors	28 questions, no essay	20 questions + 1 essay (B3: 16 + 1)
10 Aviation legislation (B1, B2)	44 questions, no essay	40 questions + 1 essay
6 Materials and hardware (B1)	80 questions	72 questions
7 Maintenance practices (A)	76 questions + 2 essays	72 questions + 2 essays
13 Aircraft systems (B2)	188 questions	180 questions
14 Propulsion (B2)	32 questions	24 questions
B3 papers	as above	mostly shorter, for example Module 4 is 8 questions and Module 16 is 68

Our papers follow either set: choose EASA or UK CAA rules on the start screen and the paper takes that size. Your exam centre or Part-147 organisation will tell you which standard applies. For the full comparison, read EASA vs UK CAA Part-66.

What each module covers

Modules 1 to 4: maths, physics and electrics

Module 1 Mathematics covers arithmetic, algebra and geometry: fractions, percentages, ratios, indices, simple equations, areas and volumes, and basic trigonometry. It is short but every later module uses it. Module 2 Physics covers matter, statics, kinetics, dynamics, fluid dynamics, thermodynamics, optics and sound. Module 3 Electrical fundamentals runs from electron theory through DC circuits, capacitance, magnetism and inductance to AC theory, transformers, filters and AC machines. Module 4 Electronic fundamentals covers semiconductors, printed circuit boards and servomechanisms, at a much deeper level for B2.

Start with these if you have no engineering background. Free first notes: Module 1 arithmetic, Module 2 matter and Module 3 electron theory.

Modules 5 to 8: systems, hardware and practice

Module 5 Digital techniques covers numbering systems, data buses, logic, computers, fibre optics, electronic displays, ESD and software management. Module 6 Materials and hardware covers ferrous and non-ferrous metals, composites, corrosion, fasteners, pipes, springs, bearings, transmissions, control cables and electrical cables. Module 7 Maintenance practices is the biggest of the common modules: safety, tools, drawings, fits and clearances, EWIS, riveting, weight and balance, aircraft handling, inspection and NDT, abnormal events, maintenance procedures and documentation, plus the essays. Module 8 Basic aerodynamics covers the atmosphere, lift and drag, theory of flight, high-speed airflow and stability.

Modules 9 and 10: people and rules

Module 9 Human factors covers human performance and limitations, social psychology, the working environment, communication, human error, safety management and the "Dirty Dozen". Module 10 Aviation legislation covers the regulatory framework (ICAO, the EU and EASA, or the UK system), Part-66 certifying staff, Part-145 and Part-CAO organisations, air operations, Part-21 certification and continuing airworthiness under Part-M, Part-ML and Part-CAMO. Module 10 is the one module where the EASA and UK content genuinely differ, because the UK now has its own regulations and authority.

Modules 11 to 17: aircraft and engines

Module 11 (11A turbine aeroplanes, 11B piston aeroplanes, 11C B3 aeroplanes) and Module 12 (helicopters) cover the airframe and every system, ATA chapter by chapter: air conditioning, electrical power, flight controls, fuel, hydraulics, ice protection, landing gear, oxygen, pneumatics and more. Module 13 is the avionics engineer's version, with autoflight, communication, navigation, surveillance and instruments in depth. Module 14 covers propulsion from the avionics side: engines, engine indicating, propeller systems, starting and ignition. Module 15 (gas turbine) and Module 16 (piston) cover engines in depth, and Module 17 covers propellers.

In what order should you take the modules?

There is no required order. A common plan for a B1 or B2 candidate studying independently looks like this:

1. Module 1, 2 and 3 first, because the rest of the syllabus builds on them.
2. Module 9 and Module 8 next: shorter papers that give early passes and confidence.
3. Module 10, ideally once you have some hangar experience, so the rules make sense.
4. Modules 4, 5 and 6, then Module 7, which draws on all of them.
5. The aircraft and engine modules (11, 12 or 13, 14, 15, 16, 17) last, because they are the longest and use everything before them.

Apprentices on a Part-147 course follow the school's order, which is usually similar. Whatever the order, remember the attempt limits: under EASA rules three attempts per module in any 12 months, under UK CAA rules three consecutive attempts and then a one-year wait, and always 90 days between a failed attempt and a retake (30 days after tailored Part-147 retraining). The Part-66 exams guide covers booking, attempts and certificates.

How to practise each module here

Every module has the same set of tools for each category that sits it:

• Quick practice: 20 free questions with an explanation after each answer, for example Module 7 quick practice for B1.1.
• Paper 1: a free full-length paper at the real size and time, such as Module 10 paper 1 for B2 or Module 15 paper 1 for B1.1.
• Papers 2 to 10 and sub-module drills with Pro, for when one paper isn't enough.
• A printable sheet of 50 questions with answers, for example the Module 9 printable questions.

Our papers are original exam-style papers, not past papers: neither authority publishes them. See Part-66 past papers for why, and for the best substitutes.

Your study plan

1. Take the free diagnostic for your category, such as the B1.1 diagnostic, B2 diagnostic or B3 diagnostic. It samples every module you sit.
2. Pick the module you will sit next and read its free first note.
3. Do quick practice daily until you score above 80%, then sit paper 1 against the clock.
4. Book the exam once you score 85% or more on three different papers, which leaves a buffer above the 75% pass mark.
5. Move on to the next module in your plan, and keep every certificate of recognition: you need them all for your licence application.