EASA & UK CAA PART-66 · CATEGORY B1.1
Thirteen exams.One licence.
The licence changes everything: your pay, your title, your options. The exams are the only thing in the way. Prep66 removes the guessing: you practise until ready isn’t a feeling, it’s a fact.
Nothing you’ll sit is missing.
Every module, and how many questions the bank holds for it. Written against both the EASA and UK CAA syllabus.
- M1Mathematics1,161
- M2Physics1,203
- M3Electrical Fundamentals1,354
- M4Electronic Fundamentals636
- M5Digital Techniques / EIS2,244
- M6Materials & Hardware2,301
- M7AMaintenance Practices5,084
- M8Basic Aerodynamics1,571
- M9AHuman Factors1,885
- M10Aviation Legislation963
- M11ATurbine Aeroplane Structures & Systems3,782
- M15Gas Turbine Engine2,565
- M17APropeller761
| Item | Description | Questions |
|---|---|---|
| M1 | Mathematics | 1,161 |
| M2 | Physics | 1,203 |
| M3 | Electrical Fundamentals | 1,354 |
| M4 | Electronic Fundamentals | 636 |
| M5 | Digital Techniques / EIS | 2,244 |
| M6 | Materials & Hardware | 2,301 |
| M7A | Maintenance Practices | 5,084 |
| M8 | Basic Aerodynamics | 1,571 |
| M9A | Human Factors | 1,885 |
| M10 | Aviation Legislation | 963 |
| M11A | Turbine Aeroplane Structures & Systems | 3,782 |
| M15 | Gas Turbine Engine | 2,565 |
| M17A | Propeller | 761 |
| Total | 13 papers, one licence | 25,510 |
EASA and the UK CAA set four of the thirteen papers differently: M6, M8, M9A and M10. The bank covers both. Every question in it is multiple choice with three options, like the papers; the essay parts of M7A, M9A and M10 are not covered. Part of each module’s count is held back and never served in practice, because that is what the three mock papers for that module are built from.
Don’t take our word for it. Answer one.
Two real questions from the Module 15 bank, exactly as set: one multiple choice and one fill in the gap. Switch format and have a go.
Multiple choice
Three options with one right answer, written like the real paper.
Fill in the gap
A word or a short term you type from memory, with nothing to pick from.
Never a bare mark
Every multiple choice question comes with a written explanation of its answer. Every gap shows you the completed sentence and the source it came from.
What would happen if all dilution air entered at the fuel nozzle?
The component that slows compressor-delivery air before the primary zone is the .
The syllabus, condensed for revision.
One for every module, written from the same source as the books, with the traps flagged and every place the sources disagree marked.
Secondary, dilution, and cooling air
What each downstream air stream does after the primary flame.
- Secondary zone. Secondary holes admit more oxygen after the primary flame. This air completes burning; consumes remaining fuel fragments and carbon monoxide; shapes the flame; and begins reducing local temperature peaks.
- Admitting a large dilution flow too early could quench the flame and raise unburned-fuel and carbon-monoxide emissions.
- Dilution zone. Large downstream holes mix cooler compressor air with the hot products.
- The aim is not merely a lower average temperature. It is an even temperature profile around the complete turbine-entry annulus.
- A hot sector can damage only a few nozzle guide vanes and turbine blades while the average cockpit indication remains within a broad limit.
- Liner film cooling. Cooling air enters through small holes, slots, or louvres and lies along the inner metal surface. The film separates the liner from the hottest gas.
- Some designs use double-wall passages; many fine transpiration holes, which distribute cooling air through a porous or closely perforated wall; or ceramic coatings.
- A blocked cooling hole can make a local hot patch. Repeated local overheating can cause oxidation; buckling; cracking; coating loss; burn-through.
Pressure loss and combustion efficiency
Why the chamber must lose some pressure, and how completely it burns its fuel.
- The chamber needs a pressure difference to drive air through swirlers, holes, and cooling passages.
- Some loss is necessary in every case. Too much loss wastes compressor work and leaves less expansion available for the turbine and nozzle.
- Combustion efficiency can approach 100% in favourable low-altitude operation and may be about 98% at altitude. These are broad illustrations. Actual efficiency depends on pressure, temperature, atomisation, chamber design, fuel, and operating point.
One source gives a total-pressure loss of about 3% of chamber-entry pressure; the other gives about 5% to 10%. The sources differ. The applicable engine data controls.
Book against the gauge, not a gut feeling.
Every answer updates your readiness score for that module: how much of the bank you’ve covered, how often you get questions right, and your best mock score once you’ve sat one, which comes out as one number read against the paper’s own pass mark. It’s an estimate built from your own answers, not a prediction.
Practise where you choose
You pick the target: a whole module, or a single topic inside it. Fixed sets of 25 questions with no timer, so you can stop whenever you want. Four modules sit on your bench at a time, and you can swap them whenever you like.
It adds up topic by topic
Every answer counts against the part of the syllabus it came from, not just the module. A weak area shows as a weak area instead of hiding in the module score.
Sit timed mocks
Full length papers under exam conditions, marked straight away, with a written explanation for every question. Mocks are the only timed thing on Prep66.
- M3Electrical FundamentalsREADY91%
- M8Basic AerodynamicsREADY87%
- M15Gas Turbine Engine72%
- M7AMaintenance Practices47%
05 WHY THIS EXISTS
Part-66 revision can feel like a grind. You’re working through huge amounts of material, trying to remember what actually matters, and still wondering whether you’re ready for the exam.
I built Prep66 because I’d sat these exams myself and knew there had to be a better way to prepare.
So Prep66 is built around one thing: helping you know what to revise, practise it properly, and walk into the exam knowing where you stand.
- 25,510QUESTIONS
Every question comes with a written explanation. All of them, not just some.
- TwoAUTHORITIES
Written to both the EASA and the UK CAA syllabuses. Where the two differ, we mark it instead of quietly picking one.
- OneSOURCE OF TRUTH
Every paper, level and topic read from the regulation itself, not copied out of another revision book.
Start free. Pay when it earns it.
One monthly subscription, one price, and no card to begin. Cancel anytime.
Free
£0/month
Study every module. 25 new questions and 25 gaps a day, per module.
- All 13 modules open
- 25 new questions a day, per module
- 25 fill in the gaps a day, per module
- Revision guides, first 10 sheets
- A readiness estimate per module
- Mock exams, Pro only
- No card required
Pro
£19.99/month
$26.99 USD · €23.99 EUR
Everything you need for full Part-66 prep.
- Unlimited new questions, all 13 modules
- Unlimited fill in the gaps, all 13 modules
- All 39 mock exams, 3 per module
- Full revision guides, both authorities, differences marked
- The full study library, all 13 books
- Progress, with projections, movement and quiet spots
- Cancel anytime
Enterprise
By arrangement
For Part-147 schools and maintenance organisations getting their mechanics licensed.
- Everything in Pro, on each account
- Unlimited questions, all modules
- Unlimited fill in the gaps, all modules
- All 39 mock exams
- Set up and billed by arrangement
Talk to us
Questions people ask.
Yes, any time from your account, with no email, no phone call and no one talking you out of it. You keep Pro to the end of the period you’ve paid for, then drop back to the free plan with all 13 modules still open.
No, and we’d rather say that up front than bury it. We don’t refund part of a month. That’s exactly why the free plan exists: all 13 modules, 25 new questions a day, per module, no card. You can judge the material properly before you pay anything.
Both daily caps come off across all 13 modules, all 39 mock exams open up (three per module), and the revision guides, the books and the syllabus documents open in full instead of stopping at a short extract. The Progress screen opens too: for every module on your bench it shows a readiness line recomputed week by week, a projection to your exam date, which topics are climbing or slipping, and which ones you were good at and haven’t been asked about since. Readiness itself isn’t a Pro feature: every module you study gets an estimate on the free plan, worked out from what you’ve answered, exactly as it is on Pro.
Yes. The exams are open to you whatever your experience; you only need it later, when you apply for the licence itself. Sitting the papers while the theory is fresh is a perfectly sensible order to do it in.
Not for the exams. Experience counts towards the licence application, not towards whether you can sit a paper. What it changes is where you start: you choose the module, or a single topic inside it, so you can work from what you already know rather than from page one.
No, and we say so plainly. This is independent exam preparation. You must sit your exam with a competent authority or an approved Part-147 organisation. We prepare you for that paper; we don’t award anything ourselves.
Every question is multiple choice with three options, the Part-66 format, exactly as the paper sets it. Question weighting, knowledge level (1/2/3) and the style of the wrong options follow the EASA Part-66 Appendix I/II structure. Nothing is copied from live papers, because that would be both illegal and useless to you.
Both. The module structure is the same under both authorities, and four papers are set differently between them: M6, M8, M9A and M10 vary in question count, time allowed, or whether an essay is attached. Every one of those variants is listed. Where the content itself differs there is one guide for each module, not two, and every place the two part ways is marked in the guide, so you can see what your authority examines and what the other one does instead, rather than trusting that something filtered it out of sight.
No. Nobody honestly can, and anyone who does is selling you something. What we can do is put you in front of the same question format under the same time pressure until your scores stop moving, and then tell you plainly where your readiness estimate sits against the pass mark.
Yes. Prep66 runs in any modern mobile browser, with nothing to install. It runs the same on a phone as on a laptop.