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Study Notes — New Edition

A new edition, and a genuinely different book: we stopped summarising the syllabus and started explaining it. The first chapter of every module is free to read.

EASA Part-66 Exam Preparation
UK CAA Part-66 Compatible Australia CASA Part 66
Updated to EU 2023/989
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EASA Part-66 Exam Preparation Online

Practice with thousands of EASA Part-66 exam questions across all 17 modules, track your progress, and join a community of aviation maintenance engineers preparing for their licence. New to it? Read what EASA Part-66 is — the licence, modules and exams explained.

Every question explained: all 17,000+ EASA Part-66 questions come with a clear, regulation-grounded explanation shown the moment you answer — so you understand why, not just memorise the answer.

All content aligned with the latest Commission Implementing Regulation (EU) 2023/989 — covering categories A, B1, B2, B2L and B3. Also fully applicable to UK CAA Part-66 candidates — the UK keeps the same Part-66 modules, exams and 75% pass mark under UK Regulation (EU) No 1321/2014. UK CAA vs EASA → Valid prep for Australia's CASA Part 66 self-study exams too. CASA vs EASA →

Part-66 worldwide: the same module-based study also prepares you for Part-66-aligned exams in the UAE (GCAA CAR-66), Qatar (QCAR Part-66), Singapore (SAR-66), Hong Kong (HKAR-66) and India (DGCA CAR-66) and Kenya (KCAA), plus where EASA / UK-CAA Part-66 exams are sat locally in Egypt (ECAA) and Nigeria (NCAA).

Aircraft Type Training: practice question banks for the Airbus A320 (CEO & NEO), A220 and A330 and Boeing 737NG, 737 MAX and 787, organised by ATA chapter with worked answers and timed practice.

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Fact of the Day

12. Helicopter aerodynamics, structures and systems

A helicopter's advancing blade tip speed is rotational speed plus forward speed, retreating is minus — at 150 kt and 400 kt tip speed, tips see 550 kt and 250 kt respectively.

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Recent Q&A Activity

H

La doublure abradable est connue en nid d'abeille, en résine synthétique ou en plastique qui réduit le bruit. Il est fait également pour être poncé par les ailette de compresseur afin d'évité un espace.

hugohoarauhoarau replied to bucks's question ·16h ago

P

Thank you for the feedback. The marked answer is correct here, and it is worth setting out why. Leaning at high power does not take the engine straight to lean of peak. Coming back from full rich, the mixture first passes through the best power and peak cylinder head temperature region, and that is where the detonation margin collapses. The excess fuel that was providing charge cooling at full rich is no longer there, flame speed falls, and combustion carries further into the stroke. That is the condition this question describes, and it is why the operating procedures for most certified engines call for full rich above roughly 75 percent power. You are correct that well lean of peak brings cylinder head temperatures back down. That is a real technique, but it depends on fuel distribution good enough to support it, and it is not a high power setting, so it sits outside what this question is asking. Of the three options given, reduced fuel flow is a cause rather than a result, and oil…

PART66Online replied to jon@efm.ltd's question ·5d ago

J

This question is worded badly. If the mixture is set lean of peak, the cylinder head temperature will decrease, NOT increase. "too lean" is very ambiguous. Please be more precise in the wording!

jon@efm.ltd asked a question ·5d ago

S

Actually, option 1 is not incorrect due to missing keywords, it is incorrect due to scope. It limits the aim to occupational health and accident prevention, whereas a human factors programme addresses the interaction of personnel with equipment, procedures and environment, and therefore targets operational safety and efficiency as well as personal well-being.

svenj88 replied to wan.yc.justin's question ·12d ago

W

#1 being wrong is it because of the missing of keywords?

wan.yc.justin asked a question ·13d ago

K

2 dots equals 4 degrees. Each point represent 2 degrees and full deflection is 10 degrees

khalidjat asked a question ·15d ago

P

You are right, the stem is too broad. On a conventional turboprop the power lever runs to the fuel control unit and a separate lever sets the governor, so option A fits that case perfectly well. I am rewording the stem to name the single lever installation, which is the only one the marked answer describes. Thanks for flagging it.

PART66Online replied to josh93's question ·21d ago

J

What about a king air 200? The power control lever only operates the FCU via the connecting rod. The prop is controlled via a separate lever. That lever only controls the primary governor. So this question is not accurate. Not all aircraft have FADEC! A&B can be correct for this question so maybe it should read "on a modern turboprop aircraft the power lever controls?"

josh93 asked a question ·21d ago

P

Good addition, thanks. 2n^2 gives 2 for the first shell and 8 for the second. I have added the formula to the question explanation for clarity.

PART66Online replied to BurtoJ's question ·25d ago

B

Formula = 2n^2 (where n = Shell #)

BurtoJ asked a question ·26d ago

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