If you want to sign off commercial aircraft as safe to fly in Europe, you need a Part-66 Aircraft Maintenance Licence (AML). The licence is split into categories, and the two most common for airline work are B1 (mechanical) and B2 (avionics). This guide explains what each one covers, how long each takes, which pays better, and how the equivalent FAA A&P certificate fits in.
The rules are set by the European Union Aviation Safety Agency under Commission Regulation (EU) 1321/2014, Annex III (Part-66). The UK follows a near-identical system through the Civil Aviation Authority. Always confirm current detail with the regulator or your training organisation.
What a Part-66 licence actually lets you do
A Part-66 licence lets you certify maintenance work on aircraft - signing the Certificate of Release to Service (CRS) that puts the aircraft back on the flight line. Without a licensed engineer's signature, the aircraft stays on the ground. Technicians without a licence can do the hands-on work, but a licensed engineer has to inspect and certify.
The licence is personal, not tied to an employer. You can take it between airlines, MROs and manufacturers.
The categories
| Category | Covers | Typical workplace |
|---|---|---|
| A | Simple scheduled line maintenance, limited defect rectification | Line stations, turnaround teams |
| B1.1 | Turbine aeroplanes (airliners, business jets) - mechanical, structures, engines, electrical | Airlines, MROs |
| B1.2 | Piston aeroplanes - mechanical, structures, engines, electrical | General aviation, flying schools |
| B1.3 | Turbine helicopters - mechanical, structures, engines, electrical | Helicopter operators |
| B1.4 | Piston helicopters | Helicopter operators |
| B2 | Avionics - instruments, autopilot, radio, electrical, basic electro-mechanical | Airlines, MROs |
| B2L | Avionics, limited scope (lighter aircraft) | General aviation |
| B3 | Piston aeroplanes under 2,000 kg, non-pressurised | General aviation |
| C | Base maintenance - certifies the whole aircraft after a heavy check | Hangar / base maintenance |
Most airline engineers train toward B1.1 or B2. The rest of this guide focuses on those two.
B1.1 (mechanical) in detail
B1.1 engineers work on the aircraft structure, engines, landing gear, flight controls, hydraulics, fuel, pneumatics and the mechanical side of the electrical system. They remove and fit components, carry out scheduled checks (A-checks on the line, C-checks and D-checks in the hangar) and sign the aircraft back into service.
The B1 modules you must pass cover basic maths and physics, materials and hardware, electrical and digital fundamentals, aerodynamics, airframe structures and systems, propulsion, and the regulations themselves (Module 10). Sixteen modules in total, from Module 1 to Module 17A (B1.1 skips Module 17B).
B2 (avionics) in detail
B2 engineers work on autopilots, instruments, communications and navigation radios, flight management systems, electrical generation and distribution, and the electronics that run modern cockpits. They do most of their work with test equipment, wiring diagrams and built-in test functions.
B2 shares many modules with B1 but goes deeper on electronics (Modules 4 and 5) and digital techniques (Module 13). Modules 11 and 15 (airframe structures, gas turbines) are lighter than for B1.
Which to pick
Pay is not set by EASA or published by any regulator - it depends on the airline, the MRO, the country and the specific type ratings held. In practice, B1 and B2 licensed engineers at the same company and type are paid broadly similarly, with additional type ratings often pushing pay up more than the category label itself. Dual-licensed engineers (B1 + B2) are rare and sought after because they can certify both sides of a job alone.
If you can only do one, pick the one that matches the work you enjoy. Mechanical hands-on work points to B1. Troubleshooting electronics with a laptop, wiring diagrams and the aircraft's own test systems points to B2.
How to train
There are two main routes.
Part-147 approved course. A full-time, two to three year course at an EASA Part-147 approved school. On completion you have passed all the modules, done the practical training, and only need the required work experience to apply for the licence. Fees vary by country and school; ask each training organisation for a written fee schedule. The current list of approved Maintenance Training Organisations (MTOs) is published by EASA at easa.europa.eu.
Self-study + apprentice route. Take a technician job at an airline or MRO, study the Part-66 modules in your own time (through distance-learning providers), sit the exams at an EASA-approved centre, and build the required practical experience on the job. This takes longer - five years is common - but you earn while you learn.
Experience and type ratings
A pass in the modules alone does not give you the licence. You also need practical experience:
- Direct from a Part-147 course: two years of relevant maintenance experience.
- Without a Part-147 course: five years of relevant maintenance experience, three of which must be after your 18th birthday.
Once the licence is issued, it is empty - it does not cover any specific aircraft type. To work on a Boeing 737 or Airbus A320 you then need a type rating for that aircraft, done through a Part-147 school and the employer. Each type rating takes four to eight weeks.
The FAA equivalent
In the United States and most of the Americas, the equivalent is the FAA Airframe and Powerplant (A&P) certificate. One certificate covers what Europe splits across B1 and B2 - the FAA takes a different approach to avionics, often done by holders of an FCC licence working alongside A&P-certified staff.
Converting between the two systems is not automatic. An A&P holder working in Europe would typically take the Part-66 modules in a reduced form (credit for prior learning varies by national authority) and pass a national regulations module. A B1 licence holder moving to the US would apply for the A&P under FAR 65.77 with evidence of training and experience, then sit the FAA written, oral and practical tests.
What airlines look for in a licensed engineer
- A clean Part-66 licence (no outstanding exam failures or waived modules)
- Type ratings that match the airline's fleet
- English language ability (ICAO level 4 for radio work; most airlines expect better in writing for defect reports)
- A clean record of signed-off work, with references from previous employers
- Willingness to work shifts, including nights and weekends - line maintenance never stops
Starting from zero
If you are starting with no experience, the quickest and cheapest route in Europe is usually:
- Apply for a technician apprenticeship with an airline or MRO. Rolls-Royce, Lufthansa Technik, SR Technics, Air France Industries, StandardAero and the big airlines all run apprentice schemes.
- During the apprenticeship, start the Part-66 modules through distance learning.
- Finish the modules and build the practical experience over four to five years.
- Apply to the national authority for the licence.
- Add a type rating paid for (or part-paid) by your employer.
For a view of what else sits in aviation, see /guides/aviation-job-roles-explained/. Open engineering roles across the airlines and MROs on our site are at engineering jobs.
Sources
Every rule in this guide is taken from the published regulations of the relevant aviation authority:
- EASA Part-66 (Aircraft Maintenance Licence): Commission Regulation (EU) No 1321/2014, Annex III, consolidated text and amendments at eur-lex.europa.eu
- EASA Part-147 (Maintenance Training Organisations): Commission Regulation (EU) No 1321/2014, Annex IV
- EASA directory of approved Part-147 MTOs: easa.europa.eu
- UK CAA equivalent requirements: caa.co.uk - Personnel Licensing, Engineering licences
- FAA Airframe and Powerplant (A&P) certificate: 14 CFR Part 65 Subpart D, faa.gov - Mechanics
- FAA mechanic certification via FAR 65.77 (experience route): ecfr.gov Title 14, Part 65
Training fees are set by individual Part-147 organisations; verify them with each school directly. Salaries are set by employers; the regulators do not publish pay data.