Part-66 Categories: A, B1, B2, B3 and C
EASA Part-66 licence categories explained: what category A, B1, B2, B3 and C each certify, the subcategories, and how limitations restrict your privileges.
Dionysis Kefalas7 min readFor Part-145 and training organisation staff
Part 2 of 5 in EASA Part-66 Aircraft Maintenance Licence Show parts
- 1The EASA Part-66 Aircraft Maintenance Licence
- 2Part-66 Categories: A, B1, B2, B3 and C
- 3Part-66 Modules and Basic Knowledge Exams
- 4Part-66 Licence: Experience and How to Apply
- 5Part-66 Validity: Type Ratings and Renewal
Quotes checked on against EASA Easy Access Rules for Continuing Airworthiness (Regulation (EU) No 1321/2014) — 2 Sep 2025 revision.
On this page
The Part-66 category map
A Part-66 aircraft maintenance licence is not one thing. It is a family of categories, and the category on your licence decides what you are allowed to certify. Before you choose modules to sit, accumulate experience, or apply, you need to know which category — and which subcategory inside it — matches the work you actually do and the aircraft you actually touch. Get that wrong and you can spend years training toward privileges you never needed.
Point 66.A.3 sets out the categories and subcategories. The quotation is the whole point, so the list is exhaustive.
(a)Aircraft maintenance licences include the following categories and, where applicable, subcategories and system ratings:
(1)Category A:
(i)Category A, is divided into the following subcategories:
A1 Aeroplanes Turbine,
A2 Aeroplanes Piston,
A3 Helicopters Turbine,
A4 Helicopters Piston.
(ii)Subcategories A1 and A3 may also be used for aircraft not covered by any A subcategory.
(2)Category B1, is divided into the following subcategories:
B1.1 Aeroplanes Turbine,
B1.2 Aeroplanes Piston,
B1.E Aeroplanes with electric power plant and MTOM below 5 700 kg,
B1.3 Helicopters Turbine,
B1.4 Helicopters Piston.
(3)Category B2
The B2 licence is applicable to all aircraft.
(4)Category B2L
The B2L licence is applicable to all aircraft other than those in Group 1 as set out in Point 66.A.5(1) and is divided into the following ‘system ratings’:
communication/navigation (com/nav),
instruments,
autoflight,
surveillance,
airframe systems.
A B2L licence shall contain, as a minimum, one system rating.
(5)Category B3
The B3 licence is applicable to piston-engine non-pressurised aeroplanes of 2 000 kg MTOM and below.
(6)Category L, divided into the following subcategories:
L1C: composite sailplanes,
L1: sailplanes,
L2C: composite powered sailplanes and composite ELA1 aeroplanes,
L2: powered sailplanes and ELA1 aeroplanes,
L3H: hot-air balloons,
L3G: gas balloons,
L4H: hot-air airships,
L4G: ELA2 gas airships,
L5: gas airships other than ELA2.
(7)Category C
The C licence is applicable to aeroplanes and helicopters.
(8)When an aircraft can be considered as included in more than one of the above (sub)categories, the Agency, based on the aircraft characteristics, shall establish the (sub)category(ies) of the licence applicable for the aircraft in its type certificate data sheet.
(b)Additionally, for aircraft and combinations of aircraft and power plant not referred to in point (a), the applicable licence (sub)category(ies) shall be the one(s) identified by the Agency.
The Agency shall identify such licence (sub)category(ies) in the operational suitability data established in accordance with Regulation (EU) No 748/2012, taking into consideration a report from the applicant for, or holder of, the aircraft type certificate which assesses the architecture and systems of the aircraft (and power plant) against the syllabus of the basic knowledge modules and knowledge levels, as relevant to the designated licence (sub)category, and the privileges established in 66.A.20.
Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.
The quotation is the list. Do not use a shortened table in its place. Points (a)(8) and (b) are in it. Group 1, named in the B2L lines, is defined in the licence overview, which quotes 66.A.5. This page does not restate that definition.
The category is the container. The privileges in 66.A.20 are what it holds.
Category A — line maintenance tasks
Category A is task-based. It does not let the holder sign off whatever they like on an A1 aeroplane. The privilege is point 1 of 66.A.20.
(a)The following privileges shall apply:
1.A category A aircraft maintenance licence permits the holder to issue certificates of release to service following minor scheduled line maintenance and simple defect rectification within the limits of tasks specifically endorsed on the certification authorisation referred to in point 145.A.35 of Annex II (Part-145). The certification privileges shall be restricted to work that the licence holder has personally performed in the maintenance organisation that issued the certification authorisation.
Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.
Read that point before you certify a line task at an ExampleMRO station. Do not shorten it.
Categories B1 and B2 — the technician licences
B1 and B2 are the core technician licences. The split between them is in 66.A.20. Read points 2 and 3, including point 3(ii), before you treat the two licences as interchangeable.
2.A category B1 aircraft maintenance licence shall permit the holder to issue certificates of release to service and to act as B1 support staff following:
maintenance performed on aircraft structure, powerplant and mechanical and electrical systems,
work on avionic systems requiring only simple tests to prove their serviceability and not requiring troubleshooting.
Category B1 includes the corresponding A subcategory.
3.A category B2 aircraft maintenance licence shall permit the holder:
(i)to issue certificates of release to service and to act as B2 support staff for following:
maintenance performed on avionic and electrical systems, and
electrical and avionics tasks within powerplant and mechanical systems, requiring only simple tests to prove their serviceability; and
(ii)to issue certificates of release to service following minor scheduled line maintenance and simple defect rectification within the limits of tasks specifically endorsed on the certification authorisation referred to in point 145.A.35 of Annex II (Part-145). This certification privilege shall be restricted to work that the licence holder has personally performed in the maintenance organisation which issued the certification authorisation and limited to the ratings already endorsed in the B2 licence.
The category B2 licence does not include any A subcategory.
Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.
Category B3 and Category C
The B3 class is in the 66.A.3 quotation. The privilege is point 5 of 66.A.20.
5.A category B3 aircraft maintenance licence shall permit the holder to issue certificates of release to service and to act as B3 support staff for the following:
maintenance performed on aeroplane structure, power plant and mechanical and electrical systems; and
work on avionics systems requiring only simple tests to prove their serviceability and not requiring troubleshooting.
Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.
Category C is point 7 of 66.A.20.
7.A category C aircraft maintenance licence shall permit the holder to issue certificates of release to service following base maintenance of the aircraft. The privileges apply to the aircraft in its entirety.
A Category C aircraft maintenance licence issued with respect to complex motor-powered aircraft shall include the privileges of category C aircraft maintenance licence also with respect to other than complex motor-powered aircraft.
Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.
Limitations
A category is the wide scope. A limitation carves some of it back out. 66.A.50 says what a limitation is and how it comes off.
(a)Limitations introduced on an aircraft maintenance licence are exclusions from the certification privileges and, in the case of limitations referred to in point 66.A.45, they affect the aircraft in its entirety.
(b)For limitations referred to in point 66.A.45, limitations shall be removed upon:
1.demonstration of appropriate experience; or
2.after a satisfactory practical assessment performed by the competent authority.
(c)For limitations referred to in point 66.A.70, limitations shall be removed upon satisfactory completion of examination on those modules/subjects defined in the applicable conversion report referred to in point 66.B.300.
Quoted word for word from Regulation (EU) No 1321/2014, Easy Access Rules for Continuing Airworthiness, 2 Sep 2025 revision.
Read the quotation for how a limitation comes off. The route depends on which point put the limitation there.
Choosing your category
Start from the work you do, then read the category and the privilege that match it. B1.E is in the 66.A.3 quotation, between B1.2 and B1.3. Do not pick a category from a shortened list.
Take an ExampleMRO mechanic who holds A1 and works on turbine aeroplanes. Moving to B1.1 is a different privilege, paid for in modules and experience. Read point 2 of 66.A.20 before you treat the two jobs as the same.
Choosing the category sets the target. The modules come next, then the experience. The module side is Part-66 Modules and Examinations: The Basic Knowledge Requirements.
Educational content, not regulatory compliance advice. Verify against the current regulation text before relying on it.
In this series
Related
- The EASA Part-66 Aircraft Maintenance Licence: A Complete GuideGuide · 6 min
- Part-66 Modules and Examinations: The Basic Knowledge RequirementsGuide · 8 min
- Part-66 Experience Requirements and Applying for Your LicenceGuide · 10 min
- Keeping Your Part-66 Licence Valid: Type Ratings, Renewal and RecencyGuide · 7 min
Written by Dionysis Kefalas. Retired Hellenic Air Force Captain and founder of Avioverse. About the author
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