EASA PART-66 · CATEGORY B1.1 · PLANNING
Part-66 B1.1: what people get wrong
Five mistakes account for most of the wasted effort on the B1.1 route, and none of them is about the difficulty of the material. Revising the wrong regime’s syllabus is the most common, because nine of the thirteen modules differ between EASA and the UK CAA. The others are letting your early passes go out of date after 10 years, budgeting for 3 years of experience when B1.1 needs 5, assuming the licence lets you certify an aircraft, and planning resits without knowing you must wait 90 days.
Checked against the current regulations on 3 August 2026. Sources: Regulation (EU) No 1321/2014, consolidated (EUR-Lex) · UK assimilated Regulation 1321/2014 (legislation.gov.uk) · UK Part-66 licensing (UK CAA).
What do people get wrong about the B1.1 route?
Every one of these is a planning error, not a knowledge gap. That is why they are expensive: they cost months rather than marks, and people usually find them late.
Revising the wrong regime’s syllabus
The two syllabuses differ across nine modules. UK Module 10 is renumbered from 10.4 onward rather than simply shortened, so mapping it number for number onto the EASA list goes wrong from that point on. In Module 15, topic 15.15 is Power augmentation systems under the UK CAA and Alternate turbine constructions under EASA. Same number, different subject.
Letting the clock run out on your early passes
Validity is counted back from the application date, so the modules you passed first are the ones at risk. Under EASA the ten years applies module by module, so clearing the theory years before you have the experience to apply can put your earliest passes out of date before you submit a Form 19.
Budgeting for the wrong experience requirement
The figures of three, two and one year belong to category A, B1.2, B1.4 and B3. B1.1 sits with B1.3 and B2, where the routes are five, three and two years. Plan on three years without a skilled worker trade qualification and you are two years short.
Assuming the licence lets you certify an aircraft
Thirteen module passes plus experience get you the licence. To certify a specific aircraft you also need the relevant type ratings and a certifying authorisation issued by the maintenance organisation you work for. Those are separate processes with separate costs.
Forgetting the 90 days between resits
A failed module cannot be retaken for 90 days. The reduction to 30 days is available only where a Part-147 approved organisation delivers retraining aimed at the subjects you failed. Private study and question banks cannot trigger it. Attempt limits differ between the regimes as well.
Which Part-66 modules are hardest?
No authority ranks them, and we publish no pass rates because we do not have any. What the regulation does hold is a depth signal: Appendix I gives each individual topic a knowledge level of 1, 2 or 3, not the module as a whole. Level 3 is the demanding one: a detailed knowledge of the theoretical and practical aspects of the subject and a capacity to combine and apply the separate elements of knowledge in a logical and comprehensive manner, including preparing sketches and schematics and interpreting results to apply corrective action.
Across the whole B1.1 syllabus under EASA, 43 topics carry level 3, and they sit in 6 of the thirteen modules. That is the closest thing there is to an objective ranking of difficulty.
- 11Aeroplane Aerodynamics, Structures and Systems33 at level 3
- 7Maintenance Practices6 at level 3
- 6Materials and Hardware1 at level 3
- 10Aviation Legislation1 at level 3
- 15Gas Turbine Engine1 at level 3
- 17Propeller1 at level 3
Read it as depth, not as a prediction. A module with one level 3 topic and eighty questions is a bigger commitment than one with three level 3 topics and twenty. Module 11 happens to be both: the longest paper at 140 questions, and the module carrying the most level 3 material.
Difficulty and planning questions
Q.01Is Module 11 the hardest Part-66 module?
It is the biggest, which is not the same thing. Module 11 is 140 questions in 175 minutes under EASA, the longest B1.1 paper by both measures, and it carries more level 3 topics than any other module. No authority ranks Part-66 modules by difficulty, and we publish no pass rates because we have none: anyone quoting a "hardest module" statistic is inventing it. What you can check is size and depth, and on both Module 11 is the biggest commitment.
Q.02Do Part-66 knowledge levels tell you how hard a module is?
Partly, and they are set more precisely than people assume. Appendix I gives a level of 1, 2 or 3 to each individual topic, not to the module as a whole, so a module is a mixture. Level 3 asks for a detailed knowledge of theory and practice and the ability to combine and apply the separate elements, including reading and preparing sketches and schematics, and interpreting results and applying corrective action. Across the whole B1.1 syllabus only 43 topics carry level 3, and they sit in 6 modules.
Q.03Does passing all 13 modules let you certify an aircraft?
No, and this is the misunderstanding that costs people most. The thirteen module passes plus the required experience get you the licence. To certify a specific aircraft you also need the relevant aircraft type ratings (66.A.45) and a certifying authorisation issued by the maintenance organisation you work for. Those are separate processes with separate costs and separate timescales, and neither is covered by anything on this page.
Q.04Can a question bank get your resit wait reduced to 30 days?
No. The reduction from 90 days to 30 happens in one case only: where a maintenance training organisation approved under Part-147 gives you a course of retraining aimed at the subjects you failed in that module. It is the organisation’s approval that triggers it. Private study, a practice bank and a prep course that is not Part-147 approved all leave the 90 days exactly where they were, whatever else they do for you.
Read next
This page answers one part of the B1.1 route in full. The rest of the guide covers the others.
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