Introduction of Aeronautical Maintenance Training

Site: Aeronautical Maintenance Training EASA Part-66
Course: Aeronautical Maintenance Training EASA Part-66
Book: Introduction of Aeronautical Maintenance Training
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Date: Monday, 4 March 2024, 3:05 PM


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1. Mandatory aircraft maintenance checks

The manufacturers (Boeing and Airbus, and others) impose on the companies regular mandatory technical visits, called A, B, C and D, corresponding to a given number of flight hours or an estimated life of a given aircraft. These aircraft maintenance visits are carried out according to a schedule determined by the manufacturers.

The A check occurs approximately every month or every 500 flight hours. It is usually carried out in one night at an airport facility.

The B check occurs approximately every 3 months. The inspection is usually performed overnight at an airport facility1. All systems, such as emergency equipment and navigation units, are examined.

The C check is performed approximately every 12-18 months or according to a specific number of actual flight hours defined by the manufacturer. This visit lasts one week. As the aircraft is taken out of service, a lot of space is needed, most often a maintenance hangar. The entire structure of the aircraft is examined with a fine-tooth comb.

The D check is also known as the "overhaul check" or "heavy maintenance check ". It is performed approximately every 4-5 years. It requires more time and space than the other types and must be performed in a maintenance hangar. It lasts at least 2 weeks, sometimes up to 2 or 3 months depending on the type of aircraft, its age and the number of flight hours. The companies generally take advantage of this time to install the latest improvements made by the manufacturers. The aircraft is then grounded for a long period, during which all its components are inspected and repaired if necessary.

2. EASA (European Union Aviation Safety Agency) Regulations

The visits described above require personnel trained in the different tasks and at the appropriate technical level for each of these tasks.

This is described in the Regulation (EC) N° 1321/2014) of 26 November 2014, amending Regulation (EC) N° 2042/2003) of 20 November 2003 on the continuing airworthiness of aircraft and aeronautical products, parts and appliances and on the approval of organisations and personnel involved in these tasks:

  • Continuing airworthiness: Annex I - Part M
  • Maintenance organisation approval: Annex II – Part 145
  • Certifying staff: Annex III – Part 66
  • Training Organisation approval - certifying staff: Annex IV - Part 147
Drapeau Europeen regulation
Click on the flag to access the European Official Journal dealing with Commission Regulation No 1312/2014.

3. Part-147 Organisations

Only those training organisations can deliver AML (Aircraft Maintenance Licence), which are described in EASA Annex 4 Part-147 “Maintenance Training Organization Approvals”.
Part-147 describes the requirements to be met by organisations seeking approval to conduct training and examinations.
Part-147 directives are dealing with the following requirements :

  • Personnel,
  • Instructional equipment and courses, Facilities,
  • Training procedures and quality system,
  • Examinations.

4. Part-66 Aircraft Maintenance Licences

Certifying Staff authorised in accordance with Part-66 will be eligible to hold certification authorisation in one or more of the following categories :

  • Cat A (Line Maintenance Certifying Mechanic);
  • Cat B1 (Maintenance Certifying Technician - Mechanical);
  • Cat B2 (Maintenance Certifying Technician - Avionics);
  • Cat B3 (Maintenance Certifying Technician – Light   Aeroplane).

4.1. The various Licences Part-66

Certifying Staff authorised in accordance with Part-66 will be eligible to hold certification authorisation in one or more of the following categories:

  • Cat A (Line Maintenance Certifying Mechanic):

A aircraft maintenance license 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 PART-145 regulations.

Cat A licenses includes  the following subcategories:
  • A1: Turbine aeroplane;
  • A2: Piston aeroplane;
  • A3: Turbine helicopter;
  • A4: Piston helicopter.

  • Cat B1 (Maintenance Certifying Technician - Mechanical):

B1 aircraft maintenance license 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.

Cat B1 licenses includes  the following subcategories:

  • B1.1: Turbine aeroplane;
  • B1.2: Piston aeroplane;
  • B1.3: Turbine helicopter;
  • B1.4: Piston helicopter.

Category B1 includes the corresponding A subcategory.

  • Cat B2 (Maintenance Certifying Technician - Avionics):
B2 license is applicable to all aircraft and concerns the maintenance of the following instruments and avionics.
  • communication/navigation (com/nav),
  • instruments,
  • autoflight,
  • surveillance,
  • airframe systems.

  • Cat B3 (Maintenance Certifying Technician – Light   Aeroplane):

B3 license is applicable to piston-engine non-pressurised aeroplanes of 2 000 kg Maximum Take-off Mass (MTOM) and below.

B2 en relation avec les autres categories

Category B2 concerns all other categories

4.2. Basic Part-66 Training Hours Volume

Typical training hours volume for people without ANY experience:

Distribution of training hours between the theoretical part and the practical part

  • A, B1, B2 licences must be validated within maximum 5 years of training.
  • All modules must be validated in order to obtain licence.
  • Sequencing and contents of modules depends on category (A, B1, B2) and/or aircraft (aeroplane/helicopter, turbine/piston engine).