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EASA Part66 Modularization

Which of the 17 modules apply to each licence category

Module applicability per Commission Implementing Regulation (EU) 2023/989, Appendix I § 2 (Modularisation). View full regulation.

How EASA Part66 modularization works

EASA Part66 is built around 17 basic-knowledge modules, from Mathematics (Module 1) to Propeller (Module 17). Each aircraft maintenance licence category requires a specific subset of these modules.

The depth of knowledge required inside a module varies by category — expressed as Level 1, 2 or 3 (familiarisation, general or detailed) inside the module syllabus. So a B1.1 candidate studies the same Module 5 as a B2 candidate, but is examined at a different depth on each subsection.

Category C is a special case: it has no module set of its own. Instead, a Category C licence is earned by holding the right combination of B1 or B2 modules — see the footnote under the matrix below.

Related: Licence categories explained · Full module syllabus · Exam structure & number of questions.

Module applicability matrix

EASA Part66 module applicability matrix per Regulation (EU) 2023/989 Appendix I — 17 modules across 8 licence-category groups.
Module A and B1 — by aircraft / engine type B3 B2 B2L C
A1 / B1.1
Turbine aeroplane		 A2 / B1.2
Piston aeroplane		 A3 / B1.3
Turbine helicopter		 A4 / B1.4
Piston helicopter
1. Mathematics X X X X X X X X
2. Physics X X X X X X X X
3. Electrical Fundamentals X X X X X X X X
4. Electronics Fundamentals X
(n/a A1)		 X
(n/a A2)		 X
(n/a A3)		 X
(n/a A4)		 X X X X
5. Digital Techniques / Electronic Instrument Systems X X X X X X X X
6. Materials and Hardware X X X X X X X X
7. Maintenance Practices X X X X X X X X
8. Basic Aerodynamics X X X X X X X X
9. Human Factors X X X X X X X X
10. Aviation Legislation X X X X X X X X
11. Aeroplane Aerodynamics, Structures and Systems X X n/a n/a X n/a n/a †
12. Helicopter Aerodynamics, Structures and Systems n/a n/a X X n/a n/a n/a †
13. Aircraft Aerodynamics, Structures and Systems n/a n/a n/a n/a n/a X X †
14. Propulsion n/a n/a n/a n/a n/a X X †
15. Gas Turbine Engines X n/a X n/a n/a n/a n/a †
16. Piston Engine n/a X n/a X X n/a n/a †
17. Propeller X X n/a n/a X n/a n/a †

X = module applies   n/a = not applicable   † = see Category C footnote below.

Module 4 (Electronics Fundamentals): applies to all four B1 subcategories but not to plain Category A (A1 / A2 / A3 / A4).

Category C combinational rule: A Category C licence is earned by holding the modules required for one of the routes below.

  • Modules 11, 15 and 17 as B1.1 (turbine aeroplane), or
  • Modules 11, 16 and 17 as B1.2 (piston aeroplane), or
  • Modules 12 and 15 as B1.3 (turbine helicopter), or
  • Modules 12 and 16 as B1.4 (piston helicopter), or
  • Modules 13 and 14 as B2 (avionics).

Free download

How to Become a Licensed Aircraft Engineer

The complete EASA Part-66 handbook — licence categories, all 17 modules, exam format and pass marks, experience and OJT, the rules in 11 countries, type ratings and continuation training. Includes 255 practice questions with explanations. 2026 Edition, PDF.

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All 17 modules at a glance

Each row links to the detailed syllabus for that module.

M1 Mathematics M2 Physics M3 Electrical Fundamentals M4 Electronics Fundamentals M5 Digital Techniques / Electronic Instrument Systems M6 Materials and Hardware M7 Maintenance Practices M8 Basic Aerodynamics M9 Human Factors M10 Aviation Legislation M11 Aeroplane Aerodynamics, Structures and Systems M12 Helicopter Aerodynamics, Structures and Systems M13 Aircraft Aerodynamics, Structures and Systems M14 Propulsion M15 Gas Turbine Engines M16 Piston Engine M17 Propeller

Frequently asked questions

How many EASA Part66 modules do I need to pass for a B1.1 licence?
For a B1.1 (turbine engined aeroplanes) licence you must pass 13 of the 17 basic-knowledge modules: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 15 and 17. Modules 12 (helicopter aerodynamics), 13 (B2 aircraft), 14 (propulsion) and 16 (piston engine) do not apply.
Why does Module 4 (Electronics Fundamentals) not apply to Category A licences?
Module 4 is required for the B1.1 / B1.2 / B1.3 / B1.4 mechanical subcategories but is marked n/a for the plain A1 / A2 / A3 / A4 line-maintenance categories. Category A engineers do not certify avionics work, so the electronics syllabus is not required.
Are modules 11A, 11B and 11C still a thing in 2023/989?
No. The current regulation merges them into a single Module 11 (Aeroplane Aerodynamics, Structures and Systems) and uses knowledge-level depth (Level 1, 2 or 3) to mark the per-category difference inside the module syllabus. Modules 7A/7B, 9A/9B and 17A/17B are likewise consolidated.
What do knowledge Levels 1, 2 and 3 mean?
Level 1 = familiarisation with the principal elements of the subject. Level 2 = general theoretical and practical knowledge plus the ability to apply it. Level 3 = detailed theoretical and practical knowledge plus the ability to combine and apply it under guidance. Each module subsection has a per-category level so a B1 exam goes deeper than an A exam on the same topic.

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