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Part-66 Module 11 Questions: Aeroplane Structures and Systems

Part-66 Module 11 covers aeroplane aerodynamics, structures and systems. B1.1 candidates sit the turbine version (11A) at 140 questions in 175 minutes, B1.2 sits the piston version (11B) at 100 questions, category A sits 108 or 72, and B3 sits 11C at 60 questions. The sizes are the same under EASA and UK CAA rules.

Updated 2026-10-19 · 10 min read · Checked against official sources

Part-66 Module 11 questions cover the aeroplane itself: how it flies, how the structure carries loads and how each system works, chapter by chapter in the ATA order you know from the maintenance manual. For B1.1 candidates, Module 11A is the longest paper in the licence. This page explains the three versions of the module, the paper size for each category under EASA and UK CAA rules, how partial exams work, and what every sub-module tests. It ends with a study plan built around free timed papers.

Part-66 Prep is an independent study aid. The syllabus is Appendix I to Part-66 and the exam standard Appendix II, in Regulation (EU) No 1321/2014 as replaced for EASA exams by Regulation (EU) 2023/989 from 12 June 2024, and in the retained UK Part-66. For the full module list by category, see the Part-66 modules guide.

Module 11A, 11B and 11C: which one do you sit?

Module 11 depends on the aeroplane your licence covers.

Version Aircraft Categories Our bank
11A Turbine aeroplanes A1, B1.1 1,509 questions
11B Piston aeroplanes A2, B1.2 821 questions
11C Piston aeroplanes at B3 level (non-pressurised, 2,000 kg MTOM and below) B3 564 questions

The UK keeps 11A, 11B and 11C as separate modules. Regulation (EU) 2023/989 merged them in the EU syllabus into one Module 11 with a column for each of A1, A2, B1.1, B1.2 and B3. The exam is still category-specific, so a B1.1 candidate sits the turbine content under both systems. The difference is mostly labelling, though it shows on certificates of recognition.

The EU has kept changing. Regulation (EU) 2025/111, applicable from 13 February 2026, restructures Module 11 again, adds a B1.E subcategory for aeroplanes with electric power plants and adds Module 18 on electric power plants, so EASA now has 18 modules. The existence of that regulation is confirmed in the EASA Easy Access Rules, but its detailed exam figures are not yet in the consolidated text. This site covers Modules 1 to 17 and has no Module 18 questions yet. In the UK, the CAA's RMT 0201 consultation proposes merging 11A, 11B and 11C too, with the law expected in 2027 and most of it in force in 2029. Until then UK exams follow the current UK Appendix II.

Part-66 Module 11 paper sizes

Category Module EASA questions / time UK CAA questions / time Marks needed
A1 11A 108 / 135 min 108 / 135 min 81
B1.1 11A 140 / 175 min 140 / 175 min 105
A2 11B 72 / 90 min 72 / 90 min 54
B1.2 11B 100 / 125 min 100 / 125 min 75
B3 11C 60 / 75 min 60 / 75 min 45

Every version has three options per question, about 75 seconds a question, a 75% pass mark and no negative marking. Module 11 has no essays in either system.

Partial exams

Under EASA rules (Appendix II point 1.12), a module exam with more than 90 minutes allowed may be split into two partial exams, and one with more than 180 minutes into three. Each part must cover complementary content, take a similar time, have a number of questions that is a multiple of four, be passed at 75% on its own and be taken at the same organisation. That means the B1.1 11A paper (175 minutes), the A1 paper (135 minutes) and the B1.2 11B paper (125 minutes) can each be split into two, if your exam organisation offers it. The 11C and A2 papers are 90 minutes or less, so they are sat in one go.

The retained UK Appendix II has no equivalent general rule. If you sit 11A with the CAA or a UK Part-147 organisation, ask how they schedule it before you book.

Key fact: A split exam is still one module. Each part has to reach 75% on its own, so a strong first half does not carry a weak second half.

What Module 11 covers, sub-module by sub-module

Knowledge levels are from Appendix I: 1 is familiarisation, 2 general working knowledge, 3 detailed knowledge. B1.1 and B1.2 work at level 3 on most systems, which is why their papers are long. Category A works mostly at level 1, and B3 at level 1 or 2. Question numbers in brackets are EASA's suggested figures for the B1.1 paper from AMC1 to Appendix II; exam setters may deviate.

11.1 Theory of flight (about 4 questions)

Aeroplane aerodynamics and flight controls: roll, pitch and yaw, elevons and ruddervators, high-lift devices, slots, slats and flaps, spoilers and lift dumpers, vortex generators, trim tabs, balance and servo tabs, and the effects of ice on lift. It builds on Module 8. The free Module 11A theory of flight note covers it.

11.2 and 11.3 Airframe structures (ATA 51 to 57)

General concepts (stress, strain, fatigue, fail-safe and damage-tolerant design, zonal identification, bonding and lightning protection), construction methods, then fuselage, doors and windows, wings, stabilisers, control surfaces and nacelles and pylons. Expect questions on load paths, the difference between primary and secondary structure, and pressurisation loads on doors.

11.4 Air conditioning and cabin pressurisation (ATA 21)

For 11A: air supply from engine bleed, APU and ground carts; air cycle and vapour cycle machines; distribution, temperature control, pressure controllers, outflow and safety valves, and warnings. Know cabin altitude versus aircraft altitude and differential pressure. 11B and 11C cover heating and ventilation in a simpler form.

11.5 Instruments and avionic systems (ATA 31, 22, 23, 34)

Instrument systems (pitot-static, gyroscopic, compasses, angle of attack, stall warning, glass cockpit) at level 2, and avionics (autoflight, communications, navigation) only at level 1: what each system does and where it sits, not how to troubleshoot it. That depth difference is a good example of how B1 and B2 split the work; B2 gets these at level 3 in Module 13.

11.6 Electrical power (ATA 24)

Batteries, DC and AC generation, emergency power, voltage regulation, power distribution, inverters, transformers, rectifiers, circuit protection and external power. Level 3 for B1, so expect system-level questions on bus switching and generator control units. Module 3 theory comes back here in aircraft form.

11.7 and 11.8 Equipment, furnishings and fire protection (ATA 25, 26)

Emergency equipment requirements, seats, harnesses and belts, cabin and cargo layout, then fire and smoke detection, extinguishing systems and system tests, and portable extinguishers. Detector types (thermal switches, continuous loops, smoke detectors) are a favourite.

11.9 Flight controls (ATA 27)

Primary and secondary controls, trim, active load control, high-lift devices, lift dump and speed brakes, actuation (manual, hydraulic, pneumatic, electrical, fly-by-wire), artificial feel, yaw damper, Mach trim, rudder limiter, gust locks, stall protection, and balancing and rigging. B1.1 sits all of it at level 3. This is one of the heaviest sub-modules.

11.10 Fuel systems (ATA 28, 47)

System layout, tanks, supply, dumping, venting and draining, cross-feed and transfer, indications and warnings, refuelling and defuelling, longitudinal balance fuel systems, and inerting (ATA 47) for 11A. Fuel quantity indication and centre-of-gravity control are common question areas.

11.11 Hydraulic power (ATA 29)

System layout, fluids, reservoirs and accumulators, pressure generation (engine-driven, electric, air-driven and ram air turbine pumps), pressure control, power distribution, indication and warning, and interfaces with other systems. Our hydraulic power drill (Pro) focuses on this sub-module.

Exam tip: Hydraulic questions often turn on what happens when one component fails: a precharge lost from an accumulator, a relief valve stuck, a pump case drain blocked. Follow the fluid around the system in your head.

11.12 Ice and rain protection (ATA 30)

Ice formation and detection, anti-icing and de-icing (thermal, electrical, chemical, pneumatic boots), probe and drain heating, wipers and rain repellent. Know the difference between preventing ice (anti-icing) and removing it (de-icing).

11.13 Landing gear (ATA 32)

Construction and shock absorbing, extension and retraction (normal and emergency), indications and warnings, wheels, brakes, anti-skid and autobraking, tyres, steering, air-ground sensing and tail protection.

11.14 to 11.17 Lights, oxygen, pneumatics, water and waste (ATA 33, 35, 36, 38)

External and internal lighting, emergency lighting; oxygen system layout, sources, storage, charging, distribution, regulation and warnings; pneumatic systems and vacuum pumps; and water and waste systems including corrosion. Oxygen safety and handling questions appear regularly.

11.18 to 11.21 (11A only)

On-board maintenance systems (ATA 45: central maintenance computers, data loading, electronic library, printing, structure monitoring), integrated modular avionics (ATA 42), cabin systems (ATA 44) and information systems (ATA 46). These appear only in 11A because they belong to large modern turbine aeroplanes. Each is at level 2 for B1.1 and gets only a few questions.

How 11A, 11B and 11C differ in content

The three versions share the same chapter headings, but piston aeroplanes are simpler, so 11B and 11C drop whole topics. From the Appendix I columns:

Topic 11A (A1, B1.1) 11B (A2, B1.2) 11C (B3)
Pressurisation Yes (B1.1 level 3) Yes (B1.2 level 3) No
Bleed air supply and air conditioning packs Yes No No
Heating and ventilation No (covered by air conditioning) Yes Yes
Flight control actuation, protection and fly-by-wire operation Yes No No
Fuel special systems and balance fuel Yes No No
Hydraulic system operation (2) Yes No No
Anti-icing systems Yes No No
Air-ground sensing Yes No No
Fire and smoke detection and fixed extinguishing Yes Yes Portable extinguishers only
Doors, cabin and cargo layout Yes Yes No
Maintenance systems, IMA, cabin and information systems Yes No No

So 11B is not just a shorter 11A: a B1.2 candidate spends more of the paper on the systems a light piston twin really has, such as heating, vacuum pumps for instruments and simpler fuel systems. 11C goes further, concentrating on the single-engine and light twin aeroplanes a B3 licence covers. If you move from B1.2 to B1.1 later, expect to sit 11A in full; the authority decides whether any 11B credit applies, so ask before you plan.

Exam tip: If you study from a general aircraft systems textbook, check each topic against the column for your version. Time spent on bleed air packs is wasted for 11B and 11C.

Practising Module 11 with exam-style papers

The sample questions on this page come from our 11A bank, which holds 1,509 original three-option questions, 218 of them free. 11B and 11C have their own banks and their own papers. Free, without an account:

Free study notes open each version: 11A theory of flight, 11B theory and structures and 11C theory and structures. Papers 2 to 10 for each, the ATA-chapter drills and the remaining notes come with Pro. As with every module, these are exam-style papers written for the app; neither EASA nor the CAA publishes past papers.

How Module 11 fits into the B1 licence

B1.1 candidates sit 11A alongside Module 15 gas turbine engine and Module 17A propeller. B1.2 sits 11B with Module 16 piston engine and 17A. B3 sits 11C, Module 16 and 17B, which the B3 licence guide covers. Helicopter subcategories sit Module 12 instead.

Most people leave Module 11 until after Modules 1 to 10, because it draws on Module 3 electrics, Module 6 materials, Module 7 practices and Module 8 aerodynamics. Practical experience helps more here than in any other module: if you work on aircraft, read the system description in the maintenance manual for your type alongside each sub-module. The Part-66 B1 licence guide sets out the full B1 module plan.

Your study plan

  1. Take the free B1.1 diagnostic to see whether Modules 1 to 10 are solid before you start Module 11.
  2. Read the free 11A theory of flight note, then work through the ATA chapters in order, giving most time to flight controls, electrical power, hydraulics, fuel and landing gear.
  3. After each chapter, do a short set of questions on it. Use the free quick practice for mixed revision.
  4. Sit the full 11A paper 1 in one sitting to build stamina, even if you plan to take the real exam in two parts.
  5. Book when you score 85% or more on three different full papers, and check with your exam organisation whether it splits the paper.

20 free Part-66 Module 11A Turbine aeroplane aerodynamics, structures and systems practice questions with answers

Try each one, then open the answer. For the timed experience use the free exam-style paper or the printable version.

  1. 1. Before charging an oxygen cylinder, the technician must allow for temperature because:

    1. A. oxygen freezes at room temperature
    2. B. colder cylinders always hold less gas
    3. C. gas pressure rises as the gas warms
    Show answer

    C. gas pressure rises as the gas warms

    Filling heats the gas, so the pressure read immediately is higher than when cool. Charts give the correct fill pressure for the ambient temperature. Filling slowly reduces heating.

  2. 2. During a duplicate inspection, the technician moves the control wheel to the right. The correct surface response is:

    1. A. right aileron down, left aileron up
    2. B. right aileron up, left aileron down
    3. C. both ailerons down
    Show answer

    B. right aileron up, left aileron down

    Turning right must roll the aircraft right, so the right wing's lift must fall (aileron up) and the left wing's rise (aileron down). Checking the sense of movement is a key part of any flight control independent inspection.

  3. 3. Wing stations (WS) on most aircraft are measured:

    1. A. outboard from the centre line or a wing reference line
    2. B. vertically upward from the cabin floor level
    3. C. forward from the wing rear spar, along the chord
    Show answer

    A. outboard from the centre line or a wing reference line

    Wing stations are spanwise locations. They are usually measured outboard from the fuselage centre line (the butt line zero) or from a defined wing root reference, and are used to locate wing ribs and fittings.

  4. 4. A trimmable horizontal stabiliser is attached to the rear fuselage by:

    1. A. fixed bolts at both the front and rear spars
    2. B. rear-spar pivots and a front-spar jackscrew
    3. C. the elevator hinge brackets and actuators only
    Show answer

    B. rear-spar pivots and a front-spar jackscrew

    The stabiliser pivots about hinge fittings near the rear spar. Its leading edge is moved up and down by a jackscrew (ballscrew) actuator attached near the front spar, which changes its angle of incidence for pitch trim.

  5. 5. Heated drain masts and water lines are provided to:

    1. A. increase water pressure in the galley
    2. B. provide heating for the rear cabin
    3. C. stop waste and water lines freezing
    Show answer

    C. stop waste and water lines freezing

    Drain masts discharge grey water overboard. Heaters stop the water freezing in the mast and lines, which would block drainage or damage the lines.

  6. 6. Emergency brakes on many transport aircraft are powered by:

    1. A. the rudder pedals alone, with no hydraulics
    2. B. a brake accumulator or alternate hydraulic system
    3. C. the engine thrust reversers
    Show answer

    B. a brake accumulator or alternate hydraulic system

    If normal brake pressure is lost, an alternate hydraulic system or a nitrogen-charged brake accumulator supplies pressure for a limited number of applications.

  7. 7. Why must pneumatic ducts be checked for insulation damage?

    1. A. Insulation increases the airflow
    2. B. Insulation prevents icing of the ducts
    3. C. Hot ducts can damage nearby items
    Show answer

    C. Hot ducts can damage nearby items

    Insulation protects surrounding items from duct heat and helps leak detection. Damaged insulation must be repaired.

  8. 8. The cabin intercommunication data system (CIDS) controls functions such as:

    1. A. engine start and fuel control
    2. B. flight control laws and protections
    3. C. PA, interphone, lights and signs
    Show answer

    C. PA, interphone, lights and signs

    CIDS is a digital system linking the flight deck and cabin crew with cabin functions: PA, interphone, passenger call, cabin lighting, signs (seat belt/no smoking), lavatory smoke indication and evacuation signalling.

  9. 9. Vortex generators are often seen near the ailerons of jet aircraft because they:

    1. A. keep flow attached over them at high Mach
    2. B. mass-balance the ailerons in flight
    3. C. act as static dischargers for the wing
    Show answer

    A. keep flow attached over them at high Mach

    At high Mach numbers shock-induced separation can reduce aileron effectiveness. Vortex generators mix energy into the boundary layer ahead of the aileron.

  10. 10. In a typical twin-engine jet, each engine is normally fed from:

    1. A. the centre tank only, all the time
    2. B. its own main tank, crossfeed closed
    3. C. the vent surge tank at the tip
    Show answer

    B. its own main tank, crossfeed closed

    Normally each engine draws from its own side, with the crossfeed valve closed, keeping the systems independent. Centre tank fuel is often used first via its own pumps.

  11. 11. A door-mounted escape slide must be automatically deployed and erected within about:

    1. A. 90 seconds
    2. B. 30 seconds
    3. C. 6 seconds
    Show answer

    C. 6 seconds

    CS 25.810 requires the slide to be erected within 6 seconds after deployment begins. This keeps the evacuation within the 90-second demonstration limit.

  12. 12. A ring laser gyro detects rotation by:

    1. A. sensing the precession of a spinning rotor
    2. B. comparing the frequencies of two opposed beams
    3. C. using a pendulous erection mechanism
    Show answer

    B. comparing the frequencies of two opposed beams

    Two laser beams travel in opposite directions around a closed path. When the unit rotates, one path appears longer, causing a frequency difference (Sagnac effect). This is measured to give rotation rate with no moving parts.

  13. 13. A continuous-loop fire detector gives a false fire warning after heavy rain. A likely cause is:

    1. A. a correctly working element
    2. B. a low fire bottle pressure
    3. C. moisture in a loop connector
    Show answer

    C. moisture in a loop connector

    Water in connectors or damaged elements can reduce resistance and trigger false warnings. Connectors are inspected, dried and resealed.

  14. 14. To make the cabin altitude climb (cabin pressure decrease), the outflow valve must:

    1. A. open further
    2. B. close further
    3. C. stay in its current position
    Show answer

    A. open further

    With a constant inflow, opening the outflow valve lets more air escape so cabin pressure falls and cabin altitude rises. Closing it keeps more air in and lowers cabin altitude.

  15. 15. Software updates on information systems are recorded so that:

    1. A. the aircraft configuration is known
    2. B. the server performance improves
    3. C. cabin crew can use the new version
    Show answer

    A. the aircraft configuration is known

    Traceability supports airworthiness. Traceable records show which software is installed, supporting airworthiness.

  16. 16. Remote data concentrators (RDCs) in an IMA architecture:

    1. A. generate electrical power for the modules
    2. B. convert sensor signals to network data
    3. C. store the navigation database
    Show answer

    B. convert sensor signals to network data

    RDCs (or remote interface units) are placed near sensors and actuators. They convert analogue and discrete signals into digital data on the network, reducing wiring weight.

  17. 17. A constant displacement pump requires a device to:

    1. A. regulate the engine gearbox speed
    2. B. unload the flow when pressure is reached
    3. C. sense any change in the fluid colour
    Show answer

    B. unload the flow when pressure is reached

    A constant displacement pump always delivers the same volume per revolution. A pressure regulator or unloading valve diverts flow to return when system pressure is reached, so the pump works at low pressure.

  18. 18. Passenger reading lights and call lights are part of the:

    1. A. emergency lighting system
    2. B. anti-collision system
    3. C. passenger service units (PSUs)
    Show answer

    C. passenger service units (PSUs)

    The PSU above each seat row includes reading lights, attendant call button, gasper outlets, signs and often oxygen masks and generators.

  19. 19. A potable water quantity indicator reads zero after filling. A likely cause is:

    1. A. the tank being overfilled with water
    2. B. a faulty quantity transmitter
    3. C. a high cabin altitude on the ground
    Show answer

    B. a faulty quantity transmitter

    If the tank has been filled (overflow seen) but the indication is zero, the fault is in the sensing system.

  20. 20. Structural health monitoring can reduce maintenance cost mainly by:

    1. A. strengthening the structure with sensors
    2. B. monitoring hidden areas without opening them
    3. C. removing the need for any structural inspection
    Show answer

    B. monitoring hidden areas without opening them

    Sensors fixed to hard-to-reach areas can be read from a connector. This avoids removing panels or interiors for routine checks. Inspections are still required when a sensor shows damage.

Frequently asked questions

+How many questions are in Part-66 Module 11A?

B1.1 sits 140 multiple-choice questions in 175 minutes and category A1 sits 108 questions in 135 minutes. The figures are the same under EASA and UK CAA rules, and the pass mark is 75%.

+What is the difference between Module 11A, 11B and 11C?

11A is turbine aeroplanes (for A1 and B1.1), 11B is piston aeroplanes (A2 and B1.2) and 11C is piston aeroplanes at B3 level. The UK keeps these as three separate modules; EASA now has one Module 11 with a column for each category, but the papers are still category-specific.

+Which categories sit Module 11?

A1 and B1.1 sit the turbine content, A2 and B1.2 the piston content, and B3 the light piston aeroplane content. Helicopter categories sit Module 12 instead, and B2 and B2L sit Module 13.

+Is Module 11A the longest Part-66 exam for B1?

Yes. At 140 questions and 175 minutes it is the longest paper any B1 subcategory sits. Only the B2 Module 13 paper is longer across all categories.

+Can Module 11A be split into partial exams?

Under EASA rules a module exam over 90 minutes may be split into two partial exams, so the 175-minute B1.1 paper can be taken in two parts if the exam organisation offers it. UK Part-66 has no general partial-exam rule, so ask the CAA or your Part-147 organisation how they run it.

+What ATA chapters are in Module 11?

Module 11 follows ATA chapters: 21 air conditioning, 22, 23 and 34 avionics overview, 24 electrical power, 25 equipment, 26 fire protection, 27 flight controls, 28 and 47 fuel, 29 hydraulics, 30 ice and rain, 31 instruments, 32 landing gear, 33 lights, 35 oxygen, 36 pneumatics, 38 water and waste, plus 51 to 57 for structures. 11A adds 42, 44, 45 and 46.

+How long should I study for Module 11A?

There is no official figure, and it depends heavily on your hangar experience. Because the paper is so long, many candidates give it two to four months of steady study. Book when you pass several full-length timed papers comfortably.

Study offline on your phone too

The Part-66 Prep: EASA & UK CAA app has the same questions plus a module board, essay coach, units drill and an attempt tracker for resit dates.

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