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The CAA website and UK Regulation (EU) No 1321/2014 Annex III (Part 66) provides significant guidance on the regulation, application methods and documentary evidence required. Unfortunately, some scenarios are unique and will require bespoke advice. Following a thorough review of guidance and regulation, should a question remain, please email the following address.

All queries should be submitted to eldweb@caa.co.uk.

The use of regulation and guidance should be your first option to answer your question, as email responses may direct you back to published information if the answer is already available online.

In any email, please include as much detail as possible in the initial submission, a simple question like “modules required to upgrade my A licence to add a B sub-category”, whilst clear to the licence holder would be impossible to answer without the detail, A1, A2, A3 or A4 adding what B1.1, B1.2, B1.3 or B1.4. Read back your question from a 3rd parties’ perspective. Additionally, this question is answered within the regulation, so this should be the first point to review.

Include your CAA Licence or Ref number if you have one. This simple step makes processing much quicker and more accurate.

UK Continuing Airworthiness Regulation

UK Regulation (EU) No 1321/2014 is broken down into the following Annexes. Section A of each Annex relates to the requirements for the applicant.

  • Annex I
  • Annex II (Part-145)
  • Annex III (Part-66)
  • Annex IV (Part-147)
  • Annex V Repealed Regulation with list of its successive amendments
  • Annex Va PART-T
  • Annex Vb (Part-ML)
  • Annex Vc (Part-CAMO)
  • Annex Vd (Part-CAO)

A full copy of the latest UK regulation can be found on the Continuing Airworthiness Regulation page of our regulatory library site.

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Licence Privileges



The different categories of licence are explained on the 66.A.20 Privileges page of our regulations library site.

B1.2 licence (i.e “aeroplane piston”), exercising privileges on a piston-engine non-pressurised aeroplanes of 2000 kg MTOM and below (i.e. category B3)

A B1.2 licence endorsed with the individual type rating or full Group 3 rating is equivalent to a B3 licence. (GM 66.A.5)

Recency requirement to maintain a Part 66 licence.

The validity of the Part-66 licence is not affected by recent experience. The requirement of 6 months’ experience within the preceding 2 years ensures that privileges are exercised by certifying staff with sufficient recent experience.

If you do not meet the experience requirement anymore, you lose your rights to exercise your privileges of certifying staff or support staff. The licence itself is valid 5 years from the last renewal. Only the certification privileges are affected by the “recency” of experience.

To regain your experience, you may either continue to accumulate maintenance experience until you gain the missing time required or meet the provisions for the issue of appropriate privileges.

Within an approved maintenance organisation this may be:

  • 6 months of continuous employment within the same organisation; or
  • 6 months split up into different blocks, employed within the same or in different organisations.

Further information can be found in AMC to 66.A.20(b)2 and CAP2377

The above is the regulatory requirement, approved organisations may be more restrictive in the application and training requirement. Refer to your Compliance Monitoring Manager.

Category A certifying authorisations (AMC 145.A.30(g))

The list of typical tasks to be carried out by a category A certifying staff at the line shown in the AMC include a (r) stating: “Any other task agreed by the CAA as a simple task for a particular aircraft type. This may include defect deferment…” (AMC 145.A.30(g).

When these conditions are met, the CAA may allow other tasks to be carried out under AMC 145.A.30(g).

Certification of Annex II aircraft with a B1.2 with a full group 3 type rating

Annex II aircraft (non-Part 21) is different and remains under the ANO & BCAR regulatory structure. Licence conversion to a BCAR licence is available and requires an oral examination with the UK CAA and submission of supporting work records.
For further information submit your requirement to ELDWEB@caa.co.uk and include you current UK Part 66 licence number.

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Gaining a CAA Part-66 Licence (Category B1 or B2)

To get a CAA Part-66 AML (Aircraft Maintenance Licence), an applicant needs:

  • Basic knowledge (66.A.25).
  • Basic experience (66.A.30).

To get an aircraft type rating (TR) endorsed in the AML, an applicant needs:

  • Type Training (Theoretical and Practical) (66.A.45)
  • On-the-job Training (OJT) for the first (TR) (66.A.45).

It’s important to understand what Group the aircraft you will be working with are for licencing requirements. Aircraft groups are described in 66.A.5.

Part-66 licences issued by the countries other than the UK are not mutually recognised in the UK system. An AML issued by a country other than the UK cannot be rendered valid as UK Part-66 AML. You must apply for the UK Part-66 AML using the normal process and demonstrate the knowledge and experience.

Close Gaining a CAA Part-66 Licence (Category B1 or B2)

UK Part-66 licence application

The initial application for a Part-66 aircraft maintenance licence shall be made to the UK CAA using the online  application form Apply for UK Part-66

This Form should be submitted together with evidence of compliance with the requirements.

See 66.A.10, 66.A.15, 66.A.25, 66.A.30, 66.A.45 and 66.A.70 and related AMC/GM. UK Regulation Part 66

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Make an amendment to a UK part 66 licence

An application for amendment of a Part-66 aircraft maintenance licence (AML) shall be made to the UK CAA website.

The application shall be submitted together with evidence of compliance with the requirements.
See 66.A.10, 66.A.15, 66.A.25, 66.A.30, 66.A.40, 66.A.45, 66.A.50, and 66.A.70 and related AMC/GM.

In all instances you must return your original Part 66 licence at time of application
See 66.A.10(c), 66.A.10(f), and AMC 66.B.110

Apply for a UK Part 66 Aircraft Maintenance Licence | Civil Aviation Authority (caa.co.uk)

Close Make an amendment to a UK part 66 licence

Academic route to apply for a UK Part 66 licence following a university degree, or studying aeronautics

Only qualifications that have be accredited by the UK CAA are acceptable. Check with your educational facility or training provider that such an approval is held and confirmed in writing.

Approval may not be obtained & applied retrospectively.

Close Academic route to apply for a UK Part 66 licence following a university degree, or studying aeronautics

Demonstrating compliance with the experience requirements

Maintenance experience should be written up in a clear manner and demonstrates that the reader has a reasonable understanding of where, when and what maintenance constitutes the experience. A task-by-task account is not necessary, but at the same time a blanket statement such as “X years maintenance experience completed” would not be acceptable.

 A maintenance logbook is desirable (see AMC 66.A.10). The CAA publish a logbook for use with UK applications document reference CAP 741 (CAP 741: Aircraft Maintenance Engineers Log Book).

Work records presented in a similar format to CAP 741 are acceptable. Each task entry should be verified by independent certifying staff. It is strongly suggested you update your work record at the earliest opportunity and on a regular basis.

Ensure all the related content is enclosed with the supporting work records and is written in a manner that gives the reader a clear understanding of the task and the work that was performed.

A simple title with an AMM reference fails to fully identify the work that was performed in most instances, additional information such as challenges faced, troubleshooting steps undertaken and any specialist tools used gives better credit to the experience gained. Multiple rows in the CAP741 can be used for each entry.

The logbook must be arranged in ATA chapter/system order, this allows maximum credit is taken for the experience gained and ensures sufficient experience has been demonstrated.

Failing to record in ATA chapter/system order will result in an application being rejected.

When submitting applications consider the sub-systems within a particular system and ensure the work records are representative of the aircraft systems & its complexity.

Close Demonstrating compliance with the experience requirements

Demonstrating experience of damage assessment and repair

Applicants should demonstrate the following:

  • Perform inspection of airframe structure for damage; evaluate different levels of damage classes IAW AMM and prepare further actions.
  • Perform different structure repairs IAW AMM, SRM or other approved data
  • Perform different corrosion protective treatment on different elements of airframe structures (e.g. wing, fuselage, empennage, tail boom, actuators, hinges, linkages, gearboxes, wheels).

Listed below are some typical structural considerations & guidance

Wooden Structures (Typically, Limitation Part 66 05, Part-66 05 & Initial Basic Licence Applications B1.2, B3 & L, subject to rating applied for)

Typical examples/considerations:

  • Perform repair of wood (primary) structure (IAW AMM and/or AC. 43.13)
  • Perform repair of plywood surface structure, needing bending (IAW AMM and/or AC. 43.13).
  • Prepare/ perform finishing of repair.
  • Perform balancing after repair /painting (IAW AMM).
  • Inspect/ test coating (tension, loose fabric, cracks – IAW AMM and/or AC.43.13).
  • Prepare/ select fabric materials (IAW AMM and/or AC.43.13).
  • Evaluate/ adapt environmental conditions for work with fabric.
  • Perform repair of fabric covering (IAW AMM and/or AC. 43.13).
  • Perform lacing (including blind lacing) IAW AMM and/or AC.43.13.
  • Perform doping and taping IAW AMM and/or AC.43.13.
  • Assess type of damage (IAW AMM/SRM and/or AC. 43.13).
  • Inspect wood structure using tapping method.
  • Prepare different types of adhesives (AMM and/or AC.43.13) for repairs
  • Prepare/ select wood materials for repairs.

Metal Tubing & Fabric Covered (Typically Limitation Part 66 01, Part-66 01 & Initial Basic Licence Applications B1.2, B3 & L, subject to rating applied for)

Typical Examples / Considerations:

  • Inspect/ test coating (tension, loose fabric, cracks – IAW AMM and/or AC.43.13).
  • Inspect/ test metal tubes (AMM and/or AC. 43.13)
  • Perform penetrant inspection of cracks (AMM and/or AC.43.13).
  • Assess type of damage (AMM and/or AC. 43.13).
  • Perform repair of metal tube fuselage structure (IAW AMM and/or AC. 43.13).
  • Prepare/ select fabric materials (IAW AMM and/or AC.43.13).
  • Evaluate/ adapt environmental conditions for work with fabric.
  • Perform repairs of fabric covering (IAW AMM and/or AC. 43.13).
  • Perform lacing (including blind lacing) IAW AMM and/or AC.43.13.
  • Perform doping and taping IAW AMM and/or AC.43.13.
  • Perform balancing after repair /painting (IAW AMM).
  • Composite (Typically Limitation Part 66 02, Part-66 02 & Initial Basic Licence Applications B1.1, B1.2, B3 & L, subject to rating applied for)
    Typical Examples / Considerations:
  • Perform tap-test/coin-test and light-test.
  • Assess class and type of damage (AMM and/or AC. 43.13).
  • Prepare different types of adhesives (AMM and/or AC.43.13) for repairs
  • Prepare/ select fiberglass materials of different stiffness (45% vs. 90%).
  • Evaluate/ adapt environmental conditions for work with composite.
  • Perform repair of composite sandwich structure (IAW AMM and/or AC. 43.13).
  • Perform repair of composite surface structure (IAW AMM and/or AC. 43.13).
  • Perform balancing after repair/painting (IAW AMM).

Metal (Typically Limitation Part 66 03 Part-66 03 & Initial Basic Licence Applications B1.1, B1.2, B3 & L, subject to rating applied for)

Typical Examples / Considerations:

  • Perform different sheet metal repairs IAW AMM, SRM or other approved data
  • Perform inspection of airframe structures for evidence of corrosion IAW AMM and prepare further actions
  • Perform different corrosion protective treatment on different elements of airframe structures (e.g wing, fuselage, empennage, tail boom, actuators, hinges, linkages, gearboxes, wheels).
  • Selection and identification of material and fasteners
  • Applicable heat treatments
  • Use of sealants and compounds
  • Perform balancing after repair /painting (IAW AMM).
Close Demonstrating experience of damage assessment and repair

Military aircraft maintenance experience

As stated in 66.A.30(e), for mechanics having a military background and seeking a Part-66 licence, the objective is to ensure adequate understanding of the civil aircraft maintenance environment, not only because of possible different aircraft technologies, but also because of practices linked to the civil environment.

The technology or systems of the civil aircraft may differ from the military aircraft version configuration (e.g. no video entertainment system; no escape slides/chutes; different fuel or electrical systems) but the experience gained in the military environment might also significantly differ from the  scope of work of the civil maintenance organisation, its procedures and policies (e.g. use and meaning of the certificate of release to service – CAA Form 1, standard parts, store and tools procedures, use of the maintenance documentation such as ADs, SB, SIL…, quality and safety management system; human factor aspects, continuing airworthiness record systems).

In addition, the interaction with the customers (i.e. the Airlines) induces new practices such as use of the aircraft technical log book, MEL, aircraft defect rectification and deferment of items; use of customer documentation (e.g. MPD, MRB, SRM, IPC); interaction with the crew; how to behave with the passengers; special procedure such as (re)fuelling, de-icing /anti-icing; communication with the tower or moving on the apron.

Finally, the requirements for the continuing airworthiness of the aircraft might significantly evolve in the civil environment. To name a few, the following items can be reminded: ADs, SBs, operational directives, CAA requirements; records and archives; repairs and modifications (use of data, CAA/FAA rules; dual-release); special inspections (e.g. CPCP, EWIS); approved maintenance programme and its effectiveness / reliability; occurrence reporting; understanding of MSG-3 methods.

The UK CAA will require correspondence from your MOD employer such as an Engineering Officer, your Officer Commanding (OC) or the Military Aviation Authority. ( or equivalent from non UK military)

  • It should be on headed paper with official stamp or seal.
  • The correspondence should clearly state your personnel details and a detailed account of your military aviation experience including dates, aircraft types, aircraft systems and your interaction with those systems / work performed. It may also include any other pertinent experience that can be directly attributed to that required by Part-66, such as basic electrical hand skills. Simply listing the ATA chapter with a generic statement would be insufficient. 
  • The standard services testimonial is not appropriate or sufficiently detailed

The letter should not resemble a CV and preferably not include references to any managerial positions or military/combat related activities, instead a chronology of your aircraft engineering experience.

It must not be written by the applicant and passed for a signature. It shall be authored by Engineering Officer or OC.

  • The letter does not need to be excessively long but the more detailed, the better (typically these letters are between 6-7 pages long, subject to the content and length of the applicants experience).
  • Any specific shortfall between the service letter and the Part 66 requirements will need to be demonstrated within the civilian experience record.

 

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Exam module validity period

UK Regulation (EU) No. 1321/2014 (amending Regulation (EC) No 2042/2003) states, the basic examinations shall be passed, and experience shall be acquired within the ten years preceding the application for an aircraft basic licence.

For further information including exam credits please the engineer exams page. Aircraft maintenance licence examinations

For information regarding the validity of examinations passed with a EU or EASA 147 please see here. Engineer licensing requirements after 1 January 2023

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Apprentice maintenance experience as part of a UK Part 147 basic course outside the UK

147.200.d(2) requires 30% of the practical training element to be carried out in an actual maintenance working environment.

For this the CAA expects the organisation to be a UK Part 145. The UK Part 147 must have a written agreement with this organisation and must oversee this work to ensure that the training is carried out in accordance with their procedures to meet the requirements of the approved course.

A UK Part 145 is required due to the objective for practical training. It must be conducted in a maintenance working environment to expose the apprentice to a real engineering environment, not just the hands on fixing of aircraft, but also the end-to-end process of aircraft maintenance.

A non-UK 145 uses a different regulation and may have different procedures that may not meet the requirements of UK Part 145 and therefore the apprentice may be learning in an environment that is not representative of what they should expect as a UK licenced engineer.

Therefore, carrying our experience outside the UK is possible, but must be planned and overseen by the UK Part 147 and in a UK Part 145 wherever that happens to be located.

Close Apprentice maintenance experience as part of a UK Part 147 basic course outside the UK

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