--- title: "3.1 Theoretical element — Part-66 · Avioverse" description: "Objective: On completion of a theoretical training course the student shall be able to demonstrate, to the levels identified in the Appendix III…" url: "https://avioverse.aero/regulations/easa/continuing-airworthiness/part-66/appendices-to-annex-iii-part-66/3-1" --- # 3.1 Theoretical element Annex III (Part-66) · Regulation (EU) No 1321/2014 · EAR revision 2 Sep 2025 IR Implementing rule ## 3.1 Theoretical element (a) Objective: On completion of a theoretical training course the student shall be able to demonstrate, to the levels identified in the Appendix III syllabus, the detailed theoretical knowledge of the [aircraft](https://avioverse.aero/glossary/easa/aircraft)’s applicable systems, structure, operations, [maintenance](https://avioverse.aero/glossary/easa/maintenance), repair, and troubleshooting in accordance with maintenance data. The student shall be able to demonstrate the use of manuals and approved procedures, including the knowledge of relevant inspections and limitations. (b) Level of training: Training levels are those levels defined in point 2 above. After the first type course for category C [certifying staff](https://avioverse.aero/glossary/easa/certifying-staff) all subsequent courses need only be to level 1. During a level 3 theoretical training, level 1 and 2 training material may be used to teach the full scope of the chapter if required. However, during the training the majority of the course material and training time shall be at the higher level. (c) Duration: The theoretical training minimum tuition hours are contained in the following table: | Category | Hours | | ---------------------------------------------------------------------------------------------------------------------------------------------- | ----- | | Aeroplanes (\*1) with a maximum take-off mass above 30 000 kg: | | | B1.1 | 150 | | B1.2 | 120 | | B2 | 100 | | C | 30 | | Aeroplanes (\*1) with a maximum take-off mass equal to or less than 30 000 kg and above 5 700 kg: | | | B1.1 | 120 | | B1.2 | 100 | | B2 | 100 | | C | 25 | | Aeroplanes (\*1) with a maximum take-off mass of 5 700 kg and below (\*2) | | | B1.1 | 80 | | B1.2 | 60 | | B1.E | 60 | | B2 | 60 | | C | 15 | | Helicopters (\*1) (\*3) | | | B1.3 | 120 | | B1.4 | 100 | | B2 | 100 | | C | 25 | | Aeroplanes and helicopters not mentioned above and [non-conventional aircraft](https://avioverse.aero/glossary/easa/non-conventional-aircraft) | | | B1, B2 and C | OSD | (\*1) [Aeroplane](https://avioverse.aero/glossary/easa/aeroplane) with piston or turbine engine or electric power plant or [helicopter](https://avioverse.aero/glossary/easa/helicopter) with piston or turbine engine. (\*2) For non-pressurised aeroplanes below 2 000 kg MTOM with piston-engine or electric power plant, the minimum duration can be reduced by 50 %. (\*3) For helicopters in Group 2 (as defined in point 66.A.5), the minimum duration can be reduced by 30 %. In the table above, ‘OSD’ means as defined 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 that contains an assessment of the required theoretical elements of knowledge of the aircraft, considering the applicable licence (sub)category on which the aircraft type would be permitted for endorsement in accordance with point 66.A.3. For the purpose of the table above, a tuition hour means 60 minutes of teaching and excludes any breaks, examination, revision, preparation and aircraft visit. These hours apply only to theoretical courses for complete aircraft/ engine combinations according to the type rating as defined by the Agency. (d) Justification of course duration: Training courses carried out in a maintenance training [organisation](https://avioverse.aero/glossary/easa/organisation) approved in accordance with Annex IV (Part-147) and courses directly approved by the competent authority shall justify their hour duration and the coverage of the full syllabus by a training needs analysis based on: the design of the aircraft type, its maintenance needs and the types of operation, detailed analysis of applicable chapters — see contents table in point 3.1(e) below, detailed competency analysis showing that the objectives as stated in point 3.1(a) above are fully met. Where the training needs analysis shows that more hours are needed, course lengths shall be longer than the minimum specified in the table. Similarly, tuition hours of differences courses or other training course combinations (such as combined B1/B2 courses), and in cases of theoretical type training courses below the figures given in point 3.1(c) above, these shall be justified to the competent authority by the training needs analysis as described above. In addition, the course must describe and justify the following: The minimum physical and/or virtual classroom attendance required of the trainee, in order to meet the objectives of the course. The maximum number of hours of physical and/or virtual classroom training per day, taking into account pedagogical and human factors principles. If the minimum attendance required is not met, the certificate of recognition shall not be issued. Additional training may be provided by the training organisation in order to meet the minimum attendance time. (e) Content: As a minimum, the elements in the Syllabus below that are specific to the aircraft type shall be covered. Additional elements introduced due to type variations, technological changes, etc. shall also be included. The training syllabus shall be focused on mechanical and electrical aspects for B1 personnel, and electrical and avionic aspects for B2. If it exists, the minimum syllabus of the operational suitability data (OSD), established in accordance with Regulation (EU) No 748/2012, shall be included. | Level Chapters | Aeroplanes turbine | | Aeroplanes piston | | Aeroplanes with electric power plant | | Helicopter turbine | | Helicopter piston | | Avionics | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------ | - | ----------------- | - | ------------------------------------ | - | ------------------ | - | ----------------- | - | -------- | | Licence category | B1.1 | C | B1.2 | C | B1.E | C | B1.3 | C | B1.4 | C | B2 | | Introduction module: | | | | | | | | | | | | | 05 Time limits/maintenance checks | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 06 Dimensions/areas (MTOM, etc.) | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 07 Lifting and Shoring | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 08 Levelling and weighing | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 09 Towing and taxiing | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 10 Parking/mooring, storing and return to Service | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 11 Placards and markings | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 12 Servicing | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | 20 Standard practices – only type particular | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | Helicopter | | | | | | | | | | | | | 18 Vibration and noise analysis (blade tracking) | — | — | — | — | — | — | 3 | 1 | 3 | 1 | — | | 60 Standard practices rotor | — | — | — | — | — | — | 3 | 1 | 3 | 1 | — | | 62 Rotors | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 1 | | 62A Rotors – monitoring and indicating | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 3 | | 63 Rotor drives | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 1 | | 63A Rotor drives – monitoring and indicating | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 3 | | 64 Tail rotor | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 1 | | 64A Tail rotor – monitoring and indicating | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 3 | | 65 Tail rotor drive | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 1 | | 65A Tail rotor drive – monitoring and indicating | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 3 | | 66 Folding blades/pylon | — | — | — | — | — | — | 3 | 1 | 3 | 1 | — | | 67 Rotors flight control | — | — | — | — | — | — | 3 | 1 | 3 | 1 | — | | 53 Airframe structure (helicopter) | — | — | — | — | — | — | 3 | 1 | 3 | 1 | — | | 25 Emergency flotation equipment | — | — | — | — | — | — | 3 | 1 | 3 | 1 | 1 | | Airframe structures | | | | | | | | | | | | | 51 Standard practices and structures (damage classification, assessment and repair) | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 53 Fuselage | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 54 Nacelles/pylons | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 55 Stabilisers | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 56 Windows | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 57 Wings | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 52 Doors | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | Zonal and station identification systems | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | | Airframe systems | | | | | | | | | | | | | 21 Air conditioning | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 21A Air supply | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 2 | | 21B Pressurisation | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 21C Safety and warning devices | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 22 Autoflight | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 3 | | 23 Communications | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 3 | | 24 Electrical power | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 25 Equipment and furnishings | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 1 | | 25A Electronic equipment including emergency equipment | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 3 | | 26 Fire protection | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 27 Flight controls | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 2 | | 27A Sys. operation: electrical/fly-by-wire | 3 | 1 | — | — | 3 | 1 | 3 | 1 | — | — | 3 | | 28 Fuel systems | 3 | 1 | 3 | 1 | — | — | 3 | 1 | 3 | 1 | 2 | | 28A Fuel systems – monitoring and indicating | 3 | 1 | 3 | 1 | — | — | 3 | 1 | 3 | 1 | 3 | | 29 Hydraulic power | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 2 | | 29A Hydraulic power – monitoring and indicating | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 30 Ice and rain protection | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 31 Indicating/recording systems | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 31A Instrument systems | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 32 Landing gear | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 2 | | 32A Landing gear – monitoring and indicating | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 33 Lights | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 34 Navigation | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 3 | | 35 Oxygen | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 2 | | 36 Pneumatic | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 2 | | 36A Pneumatic – monitoring and indicating | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | | 37 Vacuum | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 2 | | 38 Water/waste | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 2 | | 41 Water ballast | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 42 Integrated modular avionics | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 3 | | 44 Cabin systems | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 3 | | 45 On-board maintenance system (or covered in 31) | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | — | — | 3 | | 46 Information systems | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 2 | 1 | 3 | | 47 Nitrogen generation system | 3 | 1 | 3 | 1 | — | — | — | — | — | — | 2 | | 50 Cargo and accessory compartments | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 3 | 1 | 1 | | 55/57 Flight control surfaces (All) | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | Turbine engine | | | | | | | | | | | | | 70 Standard practices – engines | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 70A Constructional arrangement and operation (installation inlet, compressors, combustion section, turbine section, bearings and seals, lubrication systems) | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 70B Engine performance | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 71 Power plant | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 72 Engine turbine/turbo prop/ducted fan/unducted fan | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 73 Engine fuel and control | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 75 Air | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 76 Engine controls | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 78 Exhaust | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 79 Oil | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 80 Starting | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 82 Water injections | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 83 Accessory gear boxes | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 84 Propulsion augmentation | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 1 | | 73A FADEC | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 3 | | 74 Ignition | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 3 | | 77 Engine indicating systems | 3 | 1 | — | — | — | — | 3 | 1 | — | — | 3 | | 49 Auxiliary power units (APUs) | 3 | 1 | — | — | — | — | — | — | — | — | 2 | | Piston engine | | | | | | | | | | | | | 70 Standard practices – engines | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 70A Constructional arrangement and operation (installation, carburettors, fuel injection systems, induction, exhaust and cooling systems, supercharging/turbocharging, lubrication systems) | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 70B Engine performance | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 71 Power plant | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 73 Engine fuel and control | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 76 Engine control | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 79 Oil | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 80 Starting | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 81 Turbines | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 82 Water injections | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 83 Accessory gear boxes | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 84 Propulsion augmentation | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 1 | | 73A FADEC | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 3 | | 74 Ignition | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 3 | | 77 Engine indication systems | — | — | 3 | 1 | — | — | — | — | 3 | 1 | 3 | | Electric power plant | | | | | | | | | | | | | Electric engines | — | — | — | — | 3 | 1 | — | — | — | — | 3 | | Fuel cell and related systems | — | — | — | — | 3 | 1 | — | — | — | — | 3 | | Batteries | — | — | — | — | 3 | 1 | — | — | — | — | 3 | | Auxiliary systems to the electric power plant | — | — | — | — | 3 | 1 | — | — | — | — | 3 | | Propellers | | | | | | | | | | | | | 60A Standard practices – propeller | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 61 Propellers/propulsion | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 61A Propeller construction | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | — | | 61B Propeller pitch control | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | — | | 61C Propeller synchronising | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | 61D Propeller electronic control | 2 | 1 | 2 | 1 | 2 | 1 | — | — | — | — | 3 | | 61E Propeller ice protection | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | — | | 61F Propeller maintenance | 3 | 1 | 3 | 1 | 3 | 1 | — | — | — | — | 1 | | Special chapters for aeroplanes with a power plant other than piston/turbine/electric and other than piston/turbine helicopters | Definition of special chapters of the theoretical element of the aircraft type training is available in the OSD of the aircraft, established in accordance with Regulation (EU) No 748/2012. For these aircraft, EASA can also consider as “not required” some of the chapters contained in the above table. | | | | | | | | | | | | Special chapters for non-conventional aircraft | Definition of special chapters of the theoretical element of the aircraft type training is available in the OSD of the aircraft, established in accordance with Regulation (EU) No 748/2012. For these aircraft, EASA can also consider as “not required” some of the chapters contained in the above table. | | | | | | | | | | | IR · 3.1 — Regulation (EU) No 1321/2014 · Continuing Airworthiness Easy Access Rules · EAR revision 2 Sep 2025 [All rules in APPENDICES TO ANNEX III (Part-66)](https://avioverse.aero/regulations/easa/continuing-airworthiness/part-66/appendices-to-annex-iii-part-66) Consolidated from the EASA Easy Access Rules (revision 2 Sep 2025, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.