The Complete Guide to EASA Part-66 Aircraft Maintenance Licence (2026)

What is EASA Part-66?

EASA Part-66 is the European Aviation Safety Agency regulation that governs the licensing of aircraft maintenance engineers. It's the framework that determines who can legally sign off an aircraft as airworthy after maintenance — arguably one of the most safety-critical certifications in aviation.

Think of it this way: pilots need a licence to fly. Engineers need a licence to confirm the aircraft is safe to fly. That licence is the Aircraft Maintenance Licence (AML), and Part-66 defines exactly how you get one.

The regulation covers:

• Knowledge requirements — 17 technical modules covering everything from basic maths to complex aircraft systems
• Examination standards — multiple-choice exams with a 75% pass mark
• Experience requirements — minimum years of hands-on maintenance work
• Licence categories — different specialisations (A, B1, B2, C) for different types of work
• Privileges — what each licence category authorises you to do

The Part-66 licence is recognised across all EU/EASA member states, meaning once you have it, you can work anywhere in Europe without re-qualifying. It's also recognised or has conversion pathways in many countries outside Europe, including the Middle East, Asia-Pacific, and parts of Africa.

Who Needs a Part-66 Licence?

You need a Part-66 licence if you want to be a certifying engineer — someone who signs the Certificate of Release to Service (CRS) after maintenance. This is the legal declaration that work has been carried out correctly and the aircraft is airworthy.

You don't necessarily need a Part-66 licence to work on aircraft. Many people work as mechanics, technicians, or support staff under the supervision of a licensed engineer. However, without your own licence, you can't sign off work independently — your career ceiling is lower, and your earning potential is capped.

In practice, most people pursuing Part-66 fall into one of these categories:

• Part-147 students — studying full-time at an approved training organisation (college/academy)
• Working mechanics — already in aviation, self-studying to get licensed
• Career changers — entering aviation from engineering or technical backgrounds
• Military transfers — ex-military technicians converting to civilian licensing

Licence Categories: B1 vs B2

The two main certifying categories most engineers pursue are B1 and B2. Here's how they differ:

Aspect	B1 (Mechanical)	B2 (Avionics)
Scope	Aircraft structures, powerplant, mechanical & electrical systems	Avionics, electrical systems, instrument & navigation systems
Typical work	Engines, landing gear, flight controls, hydraulics, fuel, pneumatics	Autopilot, comms, radar, FMS, TCAS, wiring, displays
Modules required	13 modules (varies by subcategory, e.g. B1.1: M1–M7, M9–M11, M15; B1.2 adds M16, M17)	13 modules (M1–M5, M6–M7, M9–M10, M11, M13–M14)
Sub-categories	B1.1 (Turbine Aeroplane), B1.2 (Piston Aeroplane), B1.3 (Turbine Helicopter), B1.4 (Piston Helicopter)	B2 (all aircraft types)
Job market	Larger workforce, more positions available	Specialist niche, fewer candidates, strong demand
Career path	Line/base maintenance → Lead engineer → Technical services	Avionics workshop/line → Systems specialist → Design/certification

All 17 Modules Explained

Here's every Part-66 module with a brief description. The modules marked with B1/B2 are required for that category (some at different depth levels).

• 1
  Mathematics Arithmetic, algebra, geometry, trigonometry, graphs, logarithms, complex numbers. The foundation for everything else. B1 & B2.
• 2
  Physics Mechanics, thermodynamics, optics, wave motion, matter. Understanding the physical world aircraft operate in. B1 & B2.
• 3
  Electrical Fundamentals DC/AC theory, resistance, capacitance, inductance, transformers, generators, motors. Core B2 module. B1 & B2.
• 4
  Electronic Fundamentals Semiconductors, transistors, integrated circuits, printed circuit boards, logic gates. B1 & B2 (greater depth for B2).
• 5
  Digital Techniques / Electronic Instrument Systems Number systems, data buses, microprocessors, fibre optics, software management, electronic displays. B1 & B2.
• 6
  Materials & Hardware Aircraft materials, corrosion, fasteners, pipes, bearings, transmissions, cables, electrical wiring. B1 & B2.
• 7
  Maintenance Practices Safety precautions, workshop practices, tools, measurements, fits/clearances, inspections, abnormal events. B1 & B2.
• 8
  Basic Aerodynamics Physics of the atmosphere, aerodynamics, theory of flight, flight stability. B1 only.
• 9
  Human Factors Human performance, psychology, social psychology, factors affecting performance, human error, maintenance environment. B1 & B2.
• 10
  Aviation Legislation EASA regulatory framework, Part-145, Part-66, Part-M, airworthiness directives, continued airworthiness. B1 & B2.
• 11
  Aeroplane Aerodynamics, Structures & Systems Flight controls, hydraulics, fuel, pneumatics, fire protection, oxygen, ice/rain protection, landing gear. B1 & B2.
• 12
  Helicopter Aerodynamics, Structures & Systems Rotor theory, helicopter flight controls, blade tracking, vibration analysis, transmission. B1.3 & B1.4 only.
• 13
  Aircraft Aerodynamics, Structures & Systems Fuselage, wings, stabilisers, flight control surfaces, nacelles, doors, windows, structural assembly. B2.
• 14
  Propulsion Turbine engines, piston engines, engine indication, starting, ignition, fuel systems, exhaust. B2 (lighter depth than B1).
• 15
  Gas Turbine Engine Engine fundamentals, inlet, compressor, combustion, turbine, exhaust, bearings, lubrication, fuel. B1 only.
• 16
  Piston Engine Engine fundamentals, construction, fuel systems, ignition, induction, cooling, exhaust, propellers. B1.2 & B1.4.
• 17
  Propeller Propeller fundamentals, construction, pitch control, synchronising, ice protection, maintenance. B1.2 only.

Exam Format & Rules

Here's what to expect when you sit a Part-66 module exam:

Format

• Question type: Multiple-choice (MCQ) — typically 3 options per question (some authorities use 4)
• Pass mark: 75% correct answers
• Negative marking: None — always answer every question
• Calculator: Provided by the exam centre (you cannot bring your own)
• Reference material: None allowed — closed book

Number of Questions & Time

Module	B1 Questions	B2 Questions	Time (mins)
M1 Mathematics	32	32	40
M2 Physics	32	32	40
M3 Electrical	20	52	25/65
M4 Electronic	20	40	25/50
M5 Digital	20	40	25/50
M6 Materials	52	52	65
M7 Maintenance	72	60	90/75
M8 Basic Aero	20	—	25
M9 Human Factors	20	20	25
M10 Legislation	40	40	50
M11 Aeroplane Systems	180	140	225/175
M13 Structures	—	52	65
M14 Propulsion	—	24	30
M15 Gas Turbine	60	—	75

Exam Validity

Passed exams are valid for 10 years from the date of the exam. If you don't obtain your licence within 10 years of passing a module, you'll need to resit it. This gives you plenty of time, but don't leave it too late — especially if you need experience years as well.

Resits

If you fail, you must wait a minimum of 90 days before resitting the same module (30 days for subsequent resits of the same module). There's no limit on the number of attempts. Each resit requires payment of the exam fee again.

Training Routes

There are two main paths to getting your Part-66 modules complete:

Route 1: Part-147 Approved Training Organisation

This is the "traditional" route — attending a college or academy that holds Part-147 approval from an EASA national authority.

• Duration: 2–3 years full-time for the academic phase
• Cost: €8,000–€25,000 depending on country and institution
• Advantage: Structured curriculum, qualified instructors, practical workshops, only 3 years experience required
• Disadvantage: Higher cost, time commitment, rigid schedule

In Ireland, institutions like Atlantic Aviation Group (Shannon), Limerick Institute of Technology, and SOLAS-funded apprenticeships offer Part-147 approved courses.

Route 2: Self-Study

You study independently and sit exams through a Part-147 examination centre (you don't need to attend their courses — just book exam slots).

• Duration: Flexible — many complete over 3–5 years while working
• Cost: €3,000–€6,000 total (exam fees + study materials)
• Advantage: Cheaper, flexible schedule, can work while studying
• Disadvantage: Requires 5 years experience (vs 3), no structured support, higher discipline needed

Experience Requirements

Passing all the exams is only half the battle. You also need demonstrable, relevant maintenance experience:

Background	Experience Required
Part-147 graduate (relevant course)	3 years practical maintenance experience
Part-147 graduate (Cat A, B1.2, B1.4)	2 years practical maintenance experience
Self-study (no Part-147 training)	5 years practical maintenance experience
Military personnel (with conversion credits)	Varies — assessed individually by national authority

Key points about experience:

• Experience must be on in-service aircraft — workshop or manufacturing experience may only count partially
• At least 1 year must be recent experience on the aircraft category you're applying for
• Experience must be documented in a logbook signed by your supervisor
• Experience can run concurrently with your studies — start logging hours from day one of working in aviation

How to Apply for Your Licence

Once you have all modules passed and sufficient experience logged, here's the application process:

1. Gather documentation:
   • Module pass certificates (from each exam)
   • Experience logbook (signed by supervising engineer)
   • Part-147 course completion certificate (if applicable)
   • ID and passport-style photos
2. Submit to your national authority: In Ireland, this is the Irish Aviation Authority (IAA). Each EU country has their own authority (CAA in the UK, LBA in Germany, DGAC in France, etc.)
3. Pay the application fee: Typically €100–€300 depending on country
4. Wait for verification: The authority checks all documents, validates experience, and confirms exam passes. This usually takes 4–12 weeks.
5. Receive your licence: Once approved, you receive your Part-66 AML — a physical or digital document listing your categories and any type ratings.

After Getting Your Licence

Your licence alone doesn't let you sign off work on specific aircraft. You also need type ratings — training specific to each aircraft type (Boeing 737, Airbus A320, etc.). Type ratings are obtained through manufacturer-approved courses, usually provided by your employer.

Frequently Asked Questions

Can I transfer my licence to another country?

Within EASA states, your licence is valid everywhere — no transfer needed. If moving to a non-EASA country, check their bilateral agreements. Many countries (UAE, Singapore, Australia) have conversion pathways that may credit some or all of your Part-66 modules.

Do Part-66 exams expire?

Individual module passes are valid for 10 years. Your licence itself doesn't expire, but you must maintain currency by completing continuation training (typically through your employer's Part-145 organisation).

What's the difference between Part-66 and Part-145?

Part-66 is about personal licensing (individuals). Part-145 is about organisation approval (companies). A Part-145 approved maintenance organisation employs Part-66 licensed engineers to certify work.

How much do Part-66 licensed engineers earn?

In Ireland/UK: €40,000–€70,000+ depending on experience, aircraft types, and employer. Overseas contracts (Middle East, Asia) often pay €60,000–€100,000+ tax-free. B2 engineers typically command a small premium over B1 due to the specialisation.

Is Part-66 changing?

EASA periodically updates the regulation. The most recent significant changes updated Module 5 (Digital Techniques) to include modern topics like cyber security, and added requirements around unmanned aircraft (drones). Always check the current EASA AMC/GM (Acceptable Means of Compliance / Guidance Material) for the latest syllabus.