3.2 Basic Knowledge, Examination Standards & Basic Experience Requirements

3.2 Basic Knowledge, Examination Standards & Basic Experience Requirements

Quick Answer: Qualifying for an EASA Part-66 licence requires clearing two distinct hurdles: basic theoretical knowledge examinations and basic practical maintenance experience. Under Part-66 Appendix II, every module examination requires a strict 75% pass mark using three-option multiple-choice questions (MCQs) with no negative marking. Failing an exam imposes a 90-day wait before a retake (shortened to 30 days where an approved Part-147 organisation delivers retraining tailored to the failed subjects), and Appendix II point 1.13 caps attempts at three per examination in any rolling 12-month period. Passed modules remain valid for 10 years under 66.A.25. Concurrently, 66.A.30 demands between 1 and 5 years of practical maintenance experience depending on category and prior training (graduates of Part-147 basic courses require only 1 to 2 years, skilled workers require 2 to 3 years, and untrained applicants require 3 to 5 years), with at least 1 year of recent experience on operating civil aircraft.

The European aviation licensing framework balances rigorous scientific knowledge with verified hands-on maintenance competence. An applicant cannot earn a Part-66 Aircraft Maintenance Licence (AML) solely through classroom study, nor through years of unverified workshop labour. Both components—modular theoretical examinations and documented practical experience—must be fully satisfied before a Competent Authority (the National Aviation Authority of an EU Member State) will issue the initial licence.

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Basic Knowledge Examination Standards (Appendices I & II)

Appendix I to Part-66 defines the basic knowledge syllabus across 17 technical modules. Since Regulation (EU) 2023/989 the modules are numbered simply 1 to 17 (the old 7A/7B, 9A/9B, 11A/11B/11C and 17A/17B lettering has gone); the required depth and the number of examination questions now vary by licence category within each module. The module combination required depends strictly on the licence category sought. For example, a Category A applicant takes lower-depth modular exams, a Category B1 technician completes extensive structural, aerodynamic, and turbine/piston engine modules, and a Category B2 avionic technician completes in-depth electronics, digital techniques, and avionic systems modules.

The 17 Basic Knowledge Modules

• Module 1: Mathematics
• Module 2: Physics
• Module 3: Electrical Fundamentals
• Module 4: Electronic Fundamentals
• Module 5: Digital Techniques / Electronic Instrument Systems
• Module 6: Materials and Hardware
• Module 7: Maintenance Practices
• Module 8: Basic Aerodynamics
• Module 9: Human Factors
• Module 10: Aviation Legislation
• Module 11: Aeroplane Aerodynamics, Structures and Systems
• Module 12: Helicopter Aerodynamics, Structures and Systems
• Module 13: Aircraft Aerodynamics, Structures and Systems (Avionics for B2)
• Module 14: Propulsion (Avionics for B2)
• Module 15: Gas Turbine Engine
• Module 16: Piston Engine
• Module 17: Propeller

Examination Format and Passing Threshold

Appendix II to Part-66 establishes standard examination operating procedures across all Member States:

• Question Structure: All basic knowledge examinations consist of three-option multiple-choice questions (MCQs). Each question has exactly one correct answer and two plausible distractors.
• Pass Mark: The passing standard is strictly 75%. An applicant who scores 74.9% fails; there is no discretionary rounding up by examiners.
• Scoring Rules: There is no negative marking or penalty scoring for incorrect answers. Candidates are awarded 1 mark for each correct answer and 0 marks for incorrect or omitted questions.
• Time Allocation: The time allowed for each module examination is calculated at an average rate of 75 seconds per MCQ.
• Module 10 Examination Specification: Specifically for the EASA Part-66 Module 10 (Aviation Legislation) examination, candidates must answer 44 MCQs in 55 minutes (44 questions × 75 seconds = 3 300 seconds = 55 minutes), achieving at least 33 correct answers to attain the mandatory 75% pass mark.

Regulatory Modernisation: Removal of the Module 10 Essay

Historically, candidates sitting Module 7 (Maintenance Practices), Module 9 (Human Factors) and Module 10 (Aviation Legislation) had to write long-form essay questions alongside MCQs. Under Regulation (EU) 2023/989, applicable from 12 June 2024, the essay was removed from Modules 9 and 10. Module 10 is now examined exclusively by multiple-choice questions.

Do not over-generalise this. Essays were not abolished across the syllabus: amended Appendix II point 1.4 still says essay questions are drafted and evaluated using the Module 7 syllabus, and the amended question table still specifies 2 essay questions for Module 7 in every category (Category A: 76 MCQ + 2 essays, 95 min plus 40 min; Category B1 and B3: 80 MCQ + 2 essays, 100 min plus 40 min; Category B2 and B2L: 60 MCQ + 2 essays, 75 min plus 40 min). Module 7 is the only module that still carries an essay.

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Retake Rules, Penalties & Lockout Periods (66.B.200 & 66.A.25)

To prevent candidates from repeatedly sitting examinations through rote memorisation without genuine study, European regulations impose strict statutory waiting periods following an examination failure.

Standard 90-Day Waiting Period vs 30-Day Part-147 Retraining

Appendix II to Part-66, point 1.11 (as replaced by Regulation (EU) 2023/989):

"An examination in a module may not be retaken earlier than 90 days following the date of a failed examination in that module, except in the case of a maintenance training organisation approved in accordance with Annex IV (Part-147) which delivers a course of retraining tailored to the failed subjects in the particular module; the failed module may be retaken after 30 days."

• Standard retake: at least 90 days after the failed examination.
• Accelerated retake: 30 days, but only where an approved Part-147 organisation has delivered retraining tailored to the failed subjects of that module.

The Three-Attempts-Per-12-Months Cap (point 1.13)

This is the rule most often mis-taught, because the pre-2024 text worked differently. Appendix II point 1.13 now reads:

"The maximum number of attempts for each examination is three in a 12-month period."

That is a rolling 12-month window, not a fixed lock-out running from the third failure. Once an earlier attempt drops out of the preceding 12 months, a further attempt becomes available — so in practice the fourth attempt becomes possible roughly 12 months after the first of the three attempts, not 12 months after the third.

Point 1.13 also imposes a declaration duty: the applicant must give the approved Part-147 organisation or the competent authority a written statement of the number and dates of attempts during the preceding 12 months and where those attempts took place. The organisation or authority is responsible for checking the number of attempts within the applicable time frames — which is why registering with a different Member State’s authority does not reset the count.

Partial Examinations (point 1.12)

A basic knowledge examination with a maximum allowed time of more than 90 minutes may be split into two partial exams, and more than 180 minutes into three. Each partial exam must be complementary to the others, be of similar allowed time, be passed with 75 % or more, contain a number of questions that is a multiple of four, be listed on the same certificate of recognition (with the individual dates and results, without averaging), and be taken within the same organisation following the normal provisions for retaking failed exams. Module 10 (55 minutes) is below the 90-minute threshold, so it is never split.

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Validity of Passed Examination Modules (66.A.25)

Passing individual module examinations is a multi-year endeavour. A candidate might pass Module 1 (Mathematics) and Module 2 (Physics) early in their apprenticeship, while completing Module 10 (Legislation) years later.

Under Part-66.A.25, passed basic examination modules have a 10-year validity window:

• The 10-year clock starts on the date the individual module examination was successfully passed.
• The complete application for the initial Part-66 licence (or for the addition of a new category/subcategory) must be formally submitted to the Competent Authority within 10 years of passing that module.
• If more than 10 years elapse before the complete licence application is lodged, that module examination no longer counts on its own. Since Regulation (EU) 2023/989, however, 66.A.25(c) and (d) give an alternative to simply resitting: the applicant may apply to the competent authority for full or partial credits for basic knowledge examinations passed more than 10 years before the application, evidenced by an examination credit report approved under Section B, Subpart E of Part-66.
• The 10-year validity applies to each individual module examination, except for module examinations already passed as part of another licence category where that licence has already been issued.

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Basic Practical Maintenance Experience Requirements (66.A.30)

Practical experience ensures that an engineer understands not just theoretical physics, but the reality of dirty components, tight clearances, human factors, and quality systems on operating aircraft.

The Three-Tier Experience Framework

Under Part-66.A.30, practical experience requirements are structured into a three-tier system based on the applicant's prior educational and vocational background:

1. Approved Part-147 Basic Training Course Graduate: Candidates who graduate from an intensive, fully approved Part-147 basic training course (combining classroom instruction and practical workshop training).
2. Skilled Worker in a Technical Trade: Candidates who have completed formal vocational training or hold trade qualifications considered relevant by the Competent Authority in a non-aviation or manufacturing discipline (e.g., automotive technician, mechanical fitter, military weapons technician, marine engineer, industrial electrician).
3. Untrained / No Prior Relevant Training: Candidates entering the industry directly without recognised technical trade qualifications or approved courses.

Experience Requirements Matrix by Category

Exam Memory Rule: Notice the mathematical elegance of the matrix: Category A, B1.2, B1.4, and B3 require 1, 2, or 3 years. Category B1.1, B1.3, and B2 require 2, 3, or 5 years.

Category C Qualification Pathways (66.A.30(a)(3) to (a)(5))

Regulation (EU) 2023/989 replaced the Category C experience rules. Note two things candidates routinely get wrong: the correct citation is 66.A.30(a)(3) for complex motor-powered aircraft (CMPA) — not (a)(4), which now covers Category C for other than CMPA — and every route now carries an explicit base maintenance support staff element.

Category C with respect to CMPA — 66.A.30(a)(3):

• (i) 3 years of experience exercising category B1.1, B1.3 or B2 privileges as support staff, or as both support staff and certifying staff, in accordance with 145.A.35, at a maintenance organisation working on CMPA, including 12 months of experience as base maintenance support staff; or
• (ii) 5 years of experience exercising category B1.2, B1.4 or L5 privileges as support staff, or as both support staff and certifying staff, in accordance with 145.A.35, at a maintenance organisation working on CMPA, including 12 months of experience as base maintenance support staff; or
• (iii) Academic route: for applicants holding an academic degree, 3 years of experience working in an aircraft maintenance environment on a representative selection of tasks directly associated with aircraft maintenance, including 6 months of participation in the performance of base maintenance tasks on operating CMPA. (The pre-2024 wording said “observation of” base maintenance tasks; it now says participation in the performance of them.)
• (iv) Extension of an existing category C endorsed for other-than-CMPA up to CMPA: 2 years exercising B1.1, B1.2, B1.3, B1.4, B2 or L5 privileges as support staff or both, including 6 months as base maintenance support staff; or, for an academic-route category C holder, 2 years in an aircraft maintenance environment including 3 months of participation in the performance of base maintenance tasks on operating CMPA.

Category C with respect to other than CMPA — 66.A.30(a)(4): 3 years exercising category B1, B2, B2L, B3 or L privileges as support staff or both, at an organisation working on other-than-CMPA, including 6 months as base maintenance support staff; or, for academic-degree holders, 3 years in an aircraft maintenance environment including 6 months of participation in base maintenance tasks on operating other-than-CMPA aircraft.

66.A.30(a)(5) adds that the academic degree must be in a relevant technical discipline, issued by a university or other higher educational institution recognised by the competent authority — it is not restricted to aeronautical, mechanical or electrical engineering.

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Recency and Documentation of Practical Experience

Accumulating years of maintenance experience over an extended career is insufficient if that experience is obsolete or unrecorded.

The 1-Year Recency Rule

Under Part-66.A.30(d), a strict recency condition applies to initial licence applications: At least 1 year of the required basic practical experience must be recent practical experience and must be gained on operating civil aircraft of the category/subcategory sought, within the 12 months immediately preceding the application.

For Category A applicants who only require 1 year total (Tier 1 Part-147 graduates), the entire 1 year satisfies this recency rule.

Maintenance Logbook Architecture and ATA Tracking

Practical experience cannot be proven by simple employment testimonial letters. Under AMC 66.A.30, applicants must record their daily hands-on work in a formal Aircraft Maintenance Experience Logbook. Every logbook entry must detail:

• The exact calendar date of the task.
• The aircraft registration, aircraft type, and engine model.
• The Air Transport Association (ATA) chapter classification (e.g., ATA 27 Flight Controls, ATA 32 Landing Gear, ATA 73 Engine Fuel & Control).
• The specific task description (e.g., functional check, component replacement, defect rectification, structural repair).
• The maintenance environment (line maintenance vs base maintenance hangar).
• The counter-signature and licence number of the qualified supervising certifying technician.

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Practical Maintenance Scenario: Evaluating Licencing Pathways

A commercial repair station operating in Europe is assessing three candidates applying for an initial Part-66 Category B1.1 licence:

1. Candidate A: Successfully completed an EASA Part-147 approved basic training course in May 2024. Has been working as an unlicenced mechanic on operating Airbus A320 aircraft since June 2024 (accumulating 24 consecutive months of active, logged experience).
   • Eligibility Status: Eligible. Candidate A requires 2 years under Tier 1. The 24 months satisfy the total requirement, and the final 12 months satisfy the 1-year recency mandate.
2. Candidate B: Completed a 4-year certified automotive master technician apprenticeship (recognised skilled worker trade). Transitioned to civil aviation maintenance on Boeing 737 aircraft 2.5 years ago.
   • Eligibility Status: Ineligible. As a skilled worker (Tier 2) pursuing Category B1.1, Candidate B requires 3 years of practical aircraft maintenance experience. Candidate B must accrue an additional 6 months of documented experience before submitting EASA Form 19.
3. Candidate C: Passed all 17 required Category B1.1 basic knowledge modules via self-study at Competent Authority exam centres between 2015 and 2017. Has 6 years of documented aircraft maintenance experience, but ceased working on aircraft in 2022 to manage maintenance parts inventory.
   • Eligibility Status: Ineligible on two regulatory grounds. First, Candidate C's early module exams passed in 2015 now fall outside the 10-year window in 66.A.25(c), so they no longer count on their own - the candidate must either resit them or obtain an approved examination credit report under 66.A.25(d). Second, Candidate C has zero maintenance experience within the preceding 12 months, completely failing the 1-year recency rule under 66.A.30(d).

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Exam Tips & Regulatory Traps

• The Pass Mark: Always remember 75%. Any question suggesting 70% (FAA standard) or 80% is incorrect.
• The 10-Year Clock: Module passes expire after 10 years, not 5 years. (Do not confuse the 10-year examination validity with the 5-year administrative licence renewal).
• The Retake Rules: One fail = 90 days (or 30 days where an approved Part-147 organisation gives retraining tailored to the failed subjects). The cap is three attempts per examination in any 12-month period (Appendix II 1.13) — not a fixed 12-month lock-out starting at the third failure.
• Experience Matrix Splits: Memorise the split: Cat A/B1.2/B1.4/B3 is 1 / 2 / 3 years. Cat B1.1/B1.3/B2 is 2 / 3 / 5 years.
• Recency Requirement: At least 1 year must be accumulated within the 12 months preceding the application.