A structured guide to obtaining an EASA Aircraft Maintenance Licence under Part-66 and Part-147.
Two EASA regulations govern how an aircraft maintenance engineer becomes licensed in Europe. Understanding both is essential before beginning any training programme.
EASA Part-66 defines the Aircraft Maintenance Licence itself — the categories of licence that exist (A, B1, B2, C), the theoretical knowledge each requires (the numbered knowledge modules), and the practical on-the-job experience that must be accumulated before a licence is issued. Part-66 is the end goal: the licence it governs is what grants an engineer the legal authority to certify maintenance work on commercial aircraft.
EASA Part-147 governs the organisations approved to deliver the training that leads toward that licence. A Part-147 approved Maintenance Training Organisation (MTO) is authorised to conduct approved basic training courses and — critically — to conduct the Part-66 module examinations themselves. Without a Part-147 approval that includes examination authority, a training provider cannot issue the Certificates of Recognition that form the theoretical knowledge evidence package for the AML application. TRITECH holds approval number LV.147.0004, issued by the State Agency "Civil Aviation Agency" of the Republic of Latvia. This approval covers basic training for B1 (turbine aeroplanes), B1.3 (turbine helicopters), A1 (turbine aeroplanes mechanic), and B2 (avionics) categories, and includes full examination authority.
Together, Part-66 and Part-147 create a structured, internationally recognised licensing pathway. A candidate who trains at a Part-147 organisation, passes the Part-66 module examinations, accumulates the required on-the-job experience under a Part-145 maintenance organisation, and then applies to their national aviation authority will emerge with an EASA AML that is valid across all EU member states and recognised in many countries beyond.
Recognition across Europe. An EASA AML issued in Latvia by the Latvian Civil Aviation Agency carries the same validity as one issued in Germany, France, or Spain. EASA member states operate under a common regulatory framework — the licence is not a national document, it is a European one. Engineers qualified through TRITECH work throughout Europe and beyond.
The route from initial training to a type-rated AML follows a sequence prescribed by Part-66. Each stage builds on the last and cannot be skipped. The complete path typically spans three to four years, depending on training intensity, examination schedule, and the availability of Part-145 on-the-job experience placements.
Before beginning training, the target licence category must be identified. For most candidates entering commercial aviation maintenance, this means choosing between B1 (mechanical systems — engines, structures, hydraulics, flight controls) and B2 (avionics — electrical systems, instruments, navigation, communications). B1 is the more common starting point for those without a prior electronics background. A1 (mechanic, supervised only) is a faster but more limited path. Category C (base maintenance) is not an entry-level route — it requires prior B1 or B2 experience. TRITECH's instructors can advise on category selection based on prior background and employment goals.
The theoretical knowledge phase is the foundation of the EASA licensing path. Candidates attend an approved basic training programme at a Part-147 organisation — TRITECH in this context — and study all knowledge modules applicable to their target category. For B1.1 (turbine aeroplanes), this means all seventeen Part-66 modules covering subjects from mathematics and physics through to turbine engine systems and aircraft general. Each module is taught as a structured study block combining classroom instruction, practical demonstrations, and workshop exercises. At the conclusion of each module, the candidate sits a formal Part-66 module examination conducted by TRITECH under its examination authority. Each passed examination results in a Certificate of Recognition (CofR) issued by TRITECH — the formal evidence document that records theoretical knowledge attainment.
Once the theoretical knowledge phase is complete (or in some cases concurrent with its later stages), candidates must accumulate a minimum period of documented practical maintenance experience on real aircraft. This experience must be gained under a Part-145 approved maintenance organisation — an airline, MRO, or ground maintenance company holding a Part-145 approval. The minimum duration is two years for B1 and B2 categories where a full approved basic training course has been completed at a Part-147 organisation; three years is required for B1 or B2 if no prior approved basic training has been taken. For A category, the minimum is one year. Experience must be logged in a format acceptable to the national authority, verified and signed by the Part-145 organisation's Accountable Manager or Quality department, and submitted as part of the AML application. This is the stage that converts theoretical knowledge into applied technical competence.
A type rating is an endorsement on the AML that specifies the aircraft type on which the engineer is authorised to exercise certifying privileges. Without a type rating, the AML is valid but the engineer cannot independently sign Maintenance Releases on any specific type — which significantly limits employment options in commercial aviation. A type rating course covers the systems of a specific aircraft type in depth: general familiarisation, powerplant, hydraulics, fuel, electrical, avionics, flight controls, landing gear, and practical on-aircraft training. Type rating courses must be approved under Part-147. TRITECH delivers approved type training for five major types: Airbus A318/A319/A320/A321 (CFM56 and IAE V2500), Boeing 737-600/700/800/900 (CFM56), BAe 125 / Hawker series (Honeywell TFE 731), Embraer EMB-135/145 (Rolls-Royce AE3007A), and the Embraer EMB-545/550 Phenom 300 (Honeywell AS907). Type rating courses are typically taken during or immediately after the experience phase, as on-the-type experience is also required before certifying authority on that type can be exercised.
Once module examinations, basic training hours, experience, and (where applicable) type rating training are complete, the candidate compiles their evidence package and applies to the relevant national aviation authority for issuance of the AML. In Latvia, this is the State Agency "Civil Aviation Agency" (CAA Latvia). The authority reviews the CofRs, training completion certificates, and documented experience records against the Part-66 requirements for the requested category. If all requirements are satisfied, the AML is issued with the relevant category endorsements and, where applicable, specific aircraft type ratings. The licence is valid across all EASA member states and is renewed or updated as additional type ratings or categories are added throughout the engineer's career.
The theoretical knowledge curriculum for EASA Part-66 is divided into numbered modules. The full set spans from foundational science to advanced aircraft systems. The specific modules required depend on the licence category being sought. For B1.1 (turbine aeroplanes) — the most common commercial target — all seventeen modules are examined. For B2 (avionics), a partially different set applies, with avionics-specific modules replacing some of the mechanical content. Module 11A (Turbine Aeroplane Aerodynamics, Structures and Systems) is the largest and most comprehensive module in the B1 curriculum and receives the greatest share of instructional time at TRITECH.
| Module | Subject | A1 | B1.1 | B2 |
|---|---|---|---|---|
| M1 | Mathematics | Yes | Yes | Yes |
| M2 | Physics | Yes | Yes | Yes |
| M3 | Electrical Fundamentals | Yes | Yes | Yes |
| M4 | Electronic Fundamentals | — | Yes | Yes |
| M5 | Digital Techniques & Electronic Instrument Systems | — | Yes | Yes |
| M6 | Materials and Hardware | Yes | Yes | Yes |
| M7 | Maintenance Practices | Yes | Yes | Yes |
| M8 | Basic Aerodynamics | Yes | Yes | Yes |
| M9 | Human Factors | Yes | Yes | Yes |
| M10 | Aviation Legislation | Yes | Yes | Yes |
| M11A | Turbine Aeroplane Aerodynamics, Structures & Systems | Yes | Yes | — |
| M11B | Piston Aeroplane Aerodynamics, Structures & Systems | Sub-cat | Sub-cat | — |
| M12 | Helicopter Aerodynamics, Structures & Systems | — | Sub-cat | — |
| M13 | Aircraft Aerodynamics, Structures & Systems (B2) | — | — | Yes |
| M14 | Propulsion (B2) | — | — | Yes |
| M15 | Gas Turbine Engine | Yes | Yes | — |
| M16 | Piston Engine | — | Sub-cat | — |
| M17 | Propeller | — | Yes | — |
Modules are examined individually. There is no single pass/fail examination for the full programme — candidates accumulate Certificates of Recognition module by module, allowing partial completion to be paused and resumed. This is particularly relevant for working professionals who may take modules over a longer period alongside employment. Under Part-66, CofRs generally remain valid for five years from the date of examination, after which they may need to be renewed if the AML application has not yet been submitted.
Theoretical knowledge alone is not sufficient for AML issuance. Part-66 requires that candidates demonstrate practical experience on real aircraft, gained under a Part-145 approved organisation. The duration required depends on the licence category and whether the candidate has completed an approved basic training course.
| Category | With approved basic training (Part-147) | Without approved basic training | Notes |
|---|---|---|---|
| A | 1 year | 3 years | Experience must include the range of maintenance tasks relevant to the A category authorisation scope. Supervised by a B1 or B2 licence holder at a Part-145 organisation. |
| B1 | 2 years | 3 years | Must include representative experience across mechanical, structural, and avionics tasks relevant to the sub-category (e.g. B1.1 turbine aeroplanes). Experience is logged and verified by the Part-145 organisation. |
| B2 | 2 years | 3 years | Must include representative avionics and electrical systems experience. Cross-crediting of experience between B1 and B2 is possible under certain conditions — consult the relevant national authority for guidance. |
| C | Minimum 5 years as a certifying B1 or B2 engineer on aeroplanes above 30 tonnes, with demonstrated base maintenance scope. This is not an entry-level category. | Category C candidates must apply directly to the national authority with full work history documentation. TRITECH can provide relevant type training to support C category endorsements. | |
Experience must be practical and hands-on — it cannot be accumulated through administrative, quality, or planning roles alone. Part-145 organisations are required to maintain records of the maintenance tasks performed by personnel working under their organisation, and these records form the basis of the experience verification submitted to the authority. Engineers who complete their experience phase at major airlines or MROs often find that the volume and variety of tasks available accelerates the quality of their experience significantly beyond the minimum period.
Once all prerequisites are satisfied — module examinations passed, basic training hours completed, on-the-job experience accumulated and documented, and type rating training completed where applicable — the candidate applies for the AML to the national aviation authority of their country of residence or employment. There is no central EASA AML issuing authority; each member state issues licences through its own competent authority.
In Latvia, this authority is the State Agency "Civil Aviation Agency" (Civilās aviācijas aģentūra). The application requires the full set of Certificates of Recognition from TRITECH, training completion documentation, the verified experience log from the Part-145 organisation, a valid medical certificate, and identification documents. The authority reviews all submissions against the Part-66 requirements and, if satisfied, issues the AML. The licence is then valid across all EASA member states — an AML issued in Latvia is recognised in Germany, France, Spain, the Netherlands, and every other EU member state, as well as in countries outside the EU that recognise EASA licensing under bilateral aviation safety agreements.
Type ratings are added to the AML as endorsements. Each additional aircraft type requires a separate type rating course and on-the-type experience. Engineers typically hold multiple type ratings over the course of a career, with each endorsement expanding the scope of aircraft on which they can independently certify maintenance work.
The TRITECH route. Candidates can complete basic training, sit all module examinations, and attend type rating courses entirely at TRITECH in Riga, Latvia. The entire theoretical knowledge process — instruction, invigilated examination, and issuance of Certificates of Recognition — takes place under one Part-147 approved organisation. Upon completion, candidates hold a full CofR package ready for submission to the Civil Aviation Agency of Latvia or their home authority, alongside type rating certificates for any of TRITECH's five approved aircraft types. The experience phase then takes place at the Part-145 organisation of the candidate's choice, following which the AML application can be submitted. There is no requirement to engage any other training organisation or examination body for the theoretical knowledge component.
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