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Part-66 Module 8 Basic Aerodynamics Questions

Part-66 Module 8 is the basic aerodynamics exam, and it is the same size for every licence category. Under EASA rules it is 24 multiple-choice questions in 30 minutes; under UK CAA rules it is 20 questions in 25 minutes. You need 75%, so 18 correct under EASA or 15 under UK rules. It covers the atmosphere, lift and drag, flight forces and stability.

Updated 2026-10-19 · 9 min read · Checked against official sources

Part-66 Module 8 questions cover basic aerodynamics: how the atmosphere behaves, how a wing makes lift, what the four forces do in a climb, glide or turn, and what keeps an aircraft stable. It is the one paper that is identical in size for every category, and one of the shortest you will sit. This page explains the EASA and UK paper sizes and why they differ, goes through each sub-module and its traps, and shows how to prepare so the small margin does not catch you out.

Part-66 Prep is an independent study aid, not EASA, the UK CAA or a Part-147 organisation. The syllabus is Appendix I and the paper sizes are in Appendix II of Part-66: the EU text is in the EASA Easy Access Rules for Continuing Airworthiness, with the 2024 standard set by Regulation (EU) 2023/989, and the UK text is UK Part-66 on legislation.gov.uk. The Part-66 modules guide shows Module 8 alongside the others.

Part-66 Module 8 exam: EASA vs UK paper size

Category EASA questions / minutes UK CAA questions / minutes Correct answers needed (75%)
A (A1 to A4) 24 / 30 20 / 25 18 (EASA) / 15 (UK)
B1.1, B1.2, B1.3 24 / 30 20 / 25 18 (EASA) / 15 (UK)
B2 and B2L 24 / 30 20 / 25 18 (EASA) / 15 (UK)
B3 24 / 30 20 / 25 18 (EASA) / 15 (UK)

No essays, no negative marking, three options per question.

Why the two systems differ

When Regulation (EU) 2023/989 replaced the EU syllabus from 12 June 2024, it gave Module 8 a separate high-speed airflow sub-module (8.4) and moved stability and dynamics to 8.5, and the paper grew from 20 to 24 questions. The UK did not adopt the regulation. The UK syllabus still has four sub-modules, ending with 8.4 flight stability and dynamics, and the paper stays at 20 questions. The EASA vs UK CAA comparison covers the other differences.

So if you sit under UK rules, high-speed airflow is not a Module 8 topic for you. If you sit under EASA rules, budget time for Mach number, shock waves and sweepback.

Key fact: On a 24-question EASA paper each question is worth about 4%; on a 20-question UK paper each is worth 5%. Six wrong (EASA) or five wrong (UK) is still a pass; one more is a fail.

Depth by category

Every category sits every Module 8 sub-module, but at different levels. Level 1 means familiarity with the basic elements; level 2 means understanding the theory and being able to apply it.

Sub-module (EASA numbering) A B1 B2 / B2L B3
8.1 Physics of the atmosphere (ISA) 1 2 2 1
8.2 Aerodynamics 1 2 2 1
8.3 Theory of flight 1 2 2 1
8.4 High-speed airflow (EASA only) 1 2 2 1
8.5 Flight stability and dynamics 1 2 2 1

B1 and B2 sit the same paper at the same depth, so avionics candidates cannot treat Module 8 as a lighter version. Practise the paper for your category: B1.1 Module 8 paper 1, B2 Module 8 paper 1, or the hubs for category A and B3.

Module 8 sub-modules and what examiners test

8.1 Physics of the atmosphere

The International Standard Atmosphere and how it is applied to aerodynamics: the composition of air, how pressure, temperature and density change with altitude, and the standard values.

Values worth knowing by heart:

ISA quantity Value
Sea-level temperature +15 °C (288 K)
Sea-level pressure 1013.25 hPa, about 14.7 psi, 29.92 inHg
Sea-level density 1.225 kg/m³
Lapse rate in the troposphere about 2 °C per 1,000 ft (6.5 °C per 1,000 m)
Tropopause 11,000 m, about 36,000 ft
Temperature above the tropopause constant at −56.5 °C (to 20 km)

What examiners like: what happens to density as temperature or humidity rises (it falls), the difference between pressure altitude and density altitude, and finding the ISA temperature at a given height. Trap: humid air is less dense than dry air, not more, because water vapour is lighter than the nitrogen and oxygen it displaces. Our free atmosphere and aerodynamics note covers 8.1 and 8.2.

8.2 Aerodynamics

Airflow around a body, the boundary layer (laminar and turbulent), free-stream flow, relative airflow, upwash and downwash, vortices, stagnation, and the terms that describe an aerofoil: camber, chord, mean aerodynamic chord, angle of attack, angle of incidence, washout and washin. Then lift and drag, profile (parasite) and induced drag, the centre of pressure, the lift and drag coefficients, wing loading, aspect ratio, and the effect of ice and contamination.

What examiners like: the difference between angle of attack and angle of incidence, how induced drag changes with speed (it falls as speed rises) and with aspect ratio, and where the stagnation point moves as angle of attack increases. Trap: angle of incidence is fixed by the designer; angle of attack changes in flight. The Bernoulli background comes from Module 2 fluid dynamics.

Exam tip: Total drag is lowest where induced drag equals profile drag. That speed gives the best lift-to-drag ratio, which is also the best glide speed. One fact, three possible questions.

8.3 Theory of flight

The relationship between lift, weight, thrust and drag; glide ratio; steady-state flight and performance; the theory of the turn; load factor, stall, the flight envelope and structural limits; and lift augmentation (flaps, slats, slots and other high-lift devices).

What examiners like: the force balance in a climb (lift is slightly less than weight), glide ratio equal to lift over drag (and independent of weight), load factor in a level turn equal to 1 / cos of the bank angle (2 at 60°), stall speed rising with the square root of load factor, and which high-lift devices change camber and which re-energise the boundary layer. Trap: a heavier aircraft glides the same distance at the best glide angle, just faster. Drill this sub-module with the theory of flight topic and read the theory of flight note.

8.4 High-speed airflow (EASA only)

The speed of sound, subsonic, transonic and supersonic flight, Mach number, critical Mach number, compressibility buffet, shock waves, aerodynamic heating, the area rule, intake airflow and sweepback.

What examiners like: that the speed of sound depends on temperature only, that Mach number rises as an aircraft climbs at constant true airspeed (colder air), what happens across a normal shock wave (velocity falls; pressure, temperature and density rise), and why sweepback raises the critical Mach number. Trap: options that link the speed of sound to pressure or density.

8.5 Flight stability and dynamics

Longitudinal, lateral and directional stability, active and passive. Static stability (the initial tendency to return after a disturbance) and dynamic stability (what the motion does over time).

What examiners like: the three axes and which control moves the aircraft about each, the effect of centre of gravity position (forward CG is more stable with heavier control forces), the role of dihedral and sweepback in lateral stability, the fin in directional stability, and the names of dynamic modes such as Dutch roll and spiral instability. Trap: an aircraft can be statically stable but dynamically unstable, if each oscillation grows. The high-speed and stability note covers 8.4 and 8.5.

Two worked examples done by hand

Module 8 calculations are short, and numbers are chosen so you can work them without a calculator. Two typical methods:

ISA temperature. What is the ISA temperature at 6,000 ft? Start at +15 °C and subtract about 2 °C per 1,000 ft: 15 − (2 × 6) = +3 °C. If the actual temperature at that height is +13 °C, the day is ISA +10, and density altitude is higher than pressure altitude. The trap option adds the lapse rate instead of subtracting it, giving +27 °C.

Load factor and stall speed. An aircraft stalls at 60 kt in level flight. What is its stall speed in a level 60° banked turn? Load factor is 1 / cos 60° = 2. Stall speed rises with the square root of load factor: 60 × √2 ≈ 85 kt. The trap answer is 120 kt, from multiplying by the load factor itself.

On Part-66 Prep, calculation questions get new numbers from the app's generator, so you practise the method rather than remember an answer.

Where the marks are in our bank

Neither authority publishes topic statistics for the official exams. In our Module 8 bank, aerodynamics (8.2) has the most questions, followed by theory of flight (8.3), then high-speed airflow, the atmosphere and stability. Papers on the site spread questions across the sub-modules in proportions modelled on the AMC to Appendix II, so no single topic decides a paper, but a weak 8.2 or 8.3 will show.

Why the short paper needs careful preparation

Candidates often treat Module 8 as a quick win and under-prepare. The size works against you: with 24 or 20 questions, two or three unknown topics are enough to fail. Some patterns that cost marks:

  1. Mixing up angle of attack and pitch attitude. An aircraft descending in a nose-up attitude can have a high angle of attack.
  2. Getting the direction of a change wrong. "Increases" and "decreases" options are the distractors Appendix II asks examiners to use: the right relationship applied the wrong way.
  3. Forgetting the square root. Stall speed scales with the square root of load factor, not load factor itself.
  4. Treating the UK and EASA syllabuses as one. If your study material includes Mach number and shock waves and you are on UK rules, you are revising outside your Module 8 syllabus. Pre-2024 textbooks show the reverse problem for EASA candidates, who need high-speed airflow.

Where Module 8 fits in your plan

Module 8 is a natural early module. It needs only the Module 2 physics of pressure and Bernoulli, and it is short enough to prepare alongside a longer module. Many candidates pair it with Module 9 human factors or Module 10 for a few early passes while they work on the long papers.

Module 8 also sets up the aircraft modules. The aerodynamics in Module 11 (aeroplanes), Module 12 (helicopters) and Module 13 (B2) start where Module 8 stops: flight controls, high-lift systems and, for aeroplanes, high-speed flight. A solid Module 8 makes the first sub-module of those long papers much easier.

How to prepare for Module 8

Free and Pro practice

  • Free Module 8 quick practice: 20 questions with explanations, no account needed.
  • B1.1 Module 8 paper 1: the full timed paper, free. Choose EASA (24 questions) or UK CAA rules (20 questions) on the start screen.
  • Printable Module 8 sheet: 50 questions with an answer key to print or save as PDF. These are exam-style questions written for the app; EASA and the CAA do not publish past papers.
  • Pro, listed on the pricing page, adds papers 2 to 10, sub-module drills and all study notes for every category, with no pass guarantee.

Booking and retakes

You can sit Module 8 at a Part-147 organisation or, in the UK, book it directly with the CAA through the process on the CAA engineer licensing pages. After a fail you wait 90 days, or 30 days after tailored Part-147 retraining. EASA allows three attempts in any 12 months; the UK allows three consecutive attempts and then a one-year wait. A pass counts towards a licence application for 10 years.

For extra explanations with diagrams, the free FAA Aviation Maintenance Technician Handbook – General has a basic aerodynamics chapter. It is written for US mechanics and uses US units, so use it as background, not as your syllabus.

Your study plan

  1. Take the B1.1 diagnostic or the B2 diagnostic to see where Module 8 sits among your modules.
  2. Learn the ISA table above and read the free atmosphere and aerodynamics note.
  3. Do the free Module 8 quick practice and list the sub-modules you missed.
  4. Work through theory of flight, then stability, then (EASA only) high-speed airflow.
  5. Sit Module 8 paper 1 timed, on the rules that match your exam.
  6. Book when you score 85% on three different papers.

20 free Part-66 Module 8 Basic aerodynamics 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. Ground effect becomes significant when the aircraft is within approximately:

    1. A. Ten wingspans of the ground
    2. B. One wingspan of the ground
    3. C. The height of the landing gear only
    Show answer

    B. One wingspan of the ground

    Ground effect is noticeable within a height of about one wingspan and becomes large at heights below about one tenth of the span, where induced drag can be reduced by nearly half.

  2. 2. According to the ISA, how does the speed of sound change with altitude up to the tropopause?

    1. A. It decreases, because the temperature decreases
    2. B. It increases, because the density decreases
    3. C. It stays constant, because it depends only on pressure
    Show answer

    A. It decreases, because the temperature decreases

    The speed of sound a = √(γ·R·T) depends only on absolute temperature. In ISA it falls from about 340 m/s (661 kt) at sea level to about 295 m/s (573 kt) at the tropopause, then stays constant.

  3. 3. What device is fitted to many swept-wing jet aircraft to counteract Dutch roll?

    1. A. A yaw damper
    2. B. A Mach trimmer
    3. C. A stick shaker
    Show answer

    A. A yaw damper

    The yaw damper senses yaw rate and applies small rudder inputs automatically to damp the oscillation. It is an example of active (artificial) stability augmentation.

  4. 4. For an aeroplane certified in the normal category (CS-23), the positive limit load factor is typically:

    1. A. 6.0 g
    2. B. 3.8 g
    3. C. 2.5 g
    Show answer

    B. 3.8 g

    Typical limit load factors are: normal category +3.8 g / −1.52 g, utility +4.4 g / −1.76 g, aerobatic +6.0 g / −3.0 g. Large transports (CS-25) typically +2.5 g / −1.0 g.

  5. 5. Sweepback raises the critical Mach number because:

    1. A. It increases the thickness/chord ratio of the wing section
    2. B. It increases the aspect ratio of the wing for the same area
    3. C. It reduces the velocity component normal to the leading edge
    Show answer

    C. It reduces the velocity component normal to the leading edge

    With sweep angle Λ the effective Mach number normal to the leading edge is M × cos Λ. The aircraft can therefore fly faster before the flow over the wing reaches Mach 1.

  6. 6. Drag is defined as the component of the total aerodynamic reaction that:

    1. A. Acts perpendicular to the relative airflow direction
    2. B. Acts parallel to the relative airflow, opposing motion
    3. C. Acts along the chord line towards the trailing edge
    Show answer

    B. Acts parallel to the relative airflow, opposing motion

    Drag acts parallel to, and in the same direction as, the relative airflow; that is, it opposes the aircraft's motion through the air.

  7. 7. Which combination of conditions gives the HIGHEST density altitude?

    1. A. Low elevation, low temperature, low humidity
    2. B. High elevation, low temperature, low humidity
    3. C. High elevation, high temperature, high humidity
    Show answer

    C. High elevation, high temperature, high humidity

    Density falls with lower pressure, higher temperature and higher humidity. All three together produce thin air (high density altitude), which reduces lift, thrust and engine power.

  8. 8. A 'Dutch roll' is a combined:

    1. A. rolling and pitching oscillation
    2. B. yawing oscillation with no roll
    3. C. yawing and rolling oscillation
    Show answer

    C. yawing and rolling oscillation

    Dutch roll occurs when lateral stability is strong relative to directional stability; yaw dampers suppress it.

  9. 9. The best angle-of-climb speed (VX) is the speed that gives:

    1. A. The greatest height gain in the shortest time
    2. B. The lowest fuel consumption per kilometre
    3. C. The greatest height gain in the shortest horizontal distance
    Show answer

    C. The greatest height gain in the shortest horizontal distance

    VX is flown at the speed of greatest excess thrust (thrust available minus drag). It is used for clearing obstacles after take-off.

  10. 10. Transonic flight is the speed range in which:

    1. A. The airflow over the aircraft is partly subsonic and partly supersonic
    2. B. All the airflow around the aircraft is supersonic, including the wake
    3. C. All the airflow is subsonic and can be treated as incompressible
    Show answer

    A. The airflow over the aircraft is partly subsonic and partly supersonic

    The transonic range extends roughly from Mcrit (about 0.75–0.8) to about 1.2. It is the most difficult regime, with shock waves, separation, buffet and trim changes.

  11. 11. Increasing the camber of an aerofoil will generally:

    1. A. Increase the lift coefficient at a given angle of attack
    2. B. Reduce the lift coefficient at a given angle of attack
    3. C. Increase the stalling angle of attack
    Show answer

    A. Increase the lift coefficient at a given angle of attack

    Camber increases the curvature of the flow and the pressure difference at a given angle of attack, raising CL and CLmax. This is how trailing-edge flaps work, although the stall then occurs at a lower angle of attack.

  12. 12. At constant temperature, if the pressure of a mass of air is doubled, its density:

    1. A. Halves
    2. B. Doubles
    3. C. Stays the same
    Show answer

    B. Doubles

    From the gas law ρ = p/(R·T), density is directly proportional to pressure at constant temperature and inversely proportional to absolute temperature at constant pressure.

  13. 13. A high-wing aeroplane has greater lateral stability than a similar low-wing aeroplane mainly because of:

    1. A. The higher aspect ratio of a high-mounted wing
    2. B. The keel (pendulum) effect of the weight below the wing
    3. C. The more rearward centre of gravity of high-wing types
    Show answer

    B. The keel (pendulum) effect of the weight below the wing

    With the CG below the wing, the weight produces a restoring moment in a sideslip. The wing-fuselage interference in a sideslip also adds a dihedral effect on high-wing designs.

  14. 14. In a steady climb, which statement about the forces is correct?

    1. A. Lift is greater than weight, as the aircraft is climbing
    2. B. Thrust exceeds drag, as it also balances a component of weight
    3. C. Thrust equals drag and lift equals weight, as in level flight
    Show answer

    B. Thrust exceeds drag, as it also balances a component of weight

    In a steady climb at angle γ, the weight has a component W·sin γ acting rearward along the flight path. Thrust must equal drag + W·sin γ, while lift equals W·cos γ, which is slightly less than the weight.

  15. 15. A supercritical aerofoil is designed to:

    1. A. Increase the maximum lift coefficient for take-off and landing
    2. B. Weaken and delay the shock, raising the drag-divergence Mach number
    3. C. Produce stronger shocks to improve control at high Mach numbers
    Show answer

    B. Weaken and delay the shock, raising the drag-divergence Mach number

    A supercritical section has a flatter upper surface and more aft camber. The supersonic region is larger but ends in a weaker shock, raising the drag-divergence Mach number.

  16. 16. Compared with a laminar boundary layer, a turbulent boundary layer:

    1. A. Has less skin-friction drag and separates more easily
    2. B. Has more skin-friction drag but resists separation better
    3. C. Has less skin-friction drag and resists separation better
    Show answer

    B. Has more skin-friction drag but resists separation better

    In a turbulent boundary layer the mixing brings high-energy air close to the surface. This raises skin friction but keeps the flow attached longer, which is why vortex generators deliberately energise the boundary layer.

  17. 17. Passive stability of an aircraft is stability provided by:

    1. A. Flight control computers that move the controls automatically
    2. B. Design features such as tailplane, fin, dihedral and CG position
    3. C. The pilot making corrective control inputs during the flight
    Show answer

    B. Design features such as tailplane, fin, dihedral and CG position

    Passive (inherent) stability comes from the aircraft's geometry and mass distribution, without any system acting. Active stability uses sensors, computers and actuators (for example yaw dampers or fly-by-wire) to provide or improve stability.

  18. 18. A split flap:

    1. A. Moves rearward on tracks, increasing the wing area
    2. B. Is hinged from the lower surface only, and adds much drag
    3. C. Opens a slot between itself and the wing trailing edge
    Show answer

    B. Is hinged from the lower surface only, and adds much drag

    The split flap deflects only the lower surface of the trailing edge. It gives slightly more lift than a plain flap but much more drag, because of the turbulent wake behind it.

  19. 19. Two identical wings are flying at the same true airspeed and angle of attack. One is at sea level and one at a density altitude where the air density is half that at sea level. The lift at altitude is:

    1. A. The same as at sea level
    2. B. Half of that at sea level
    3. C. A quarter of that at sea level
    Show answer

    B. Half of that at sea level

    L = CL × ½ρV² × S. With CL, V and S unchanged, lift is directly proportional to density, so halving ρ halves the lift. To maintain lift at altitude the aircraft must fly faster (higher TAS) or at a higher angle of attack.

  20. 20. Boundary-layer control devices such as vortex generators and blown flaps belong to which group?

    1. A. Trim devices
    2. B. Primary flight controls
    3. C. Lift-augmentation devices
    Show answer

    C. Lift-augmentation devices

    Lift augmentation includes flaps, slats, slots and boundary-layer control. They all delay separation or increase camber so that CLmax is raised and the aircraft can fly at lower speeds.

Frequently asked questions

+How many questions are in Part-66 Module 8?

Under EASA rules, 24 questions in 30 minutes for every category. Under UK CAA rules, 20 questions in 25 minutes for every category. There are no essays in either system, and the pass mark is 75%.

+Is Module 8 easy?

It is one of the shortest papers and the content is compact, so many candidates take it early. The catch is the margin: you can only get 6 wrong under EASA rules or 5 under UK rules, so a few careless answers on a formula or a definition can mean a fail.

+What is in Module 8 basic aerodynamics?

Under EASA rules: the physics of the atmosphere and the ISA, aerodynamics (airflow, lift, drag, aerofoil terms), theory of flight (forces, glide, turns, load factor, high-lift devices), high-speed airflow, and flight stability and dynamics. The UK syllabus has the same core topics but no high-speed airflow sub-module.

+Why is Module 8 24 questions under EASA and 20 under UK rules?

Regulation (EU) 2023/989 rewrote the EU syllabus and exam standard from 12 June 2024, adding a high-speed airflow sub-module to Module 8 and raising the paper to 24 questions. The UK did not adopt that regulation, so UK papers keep the earlier 20-question size.

+Is Module 8 the same for B1 and B2?

Yes. Every category sits the same size of paper. B1, B2 and B2L are examined at level 2 on every sub-module and categories A and B3 at level 1, so the A and B3 questions are more descriptive and less calculation-based.

+How long should I study for Module 8?

No authority publishes a figure, and it depends on your physics background. It is usually one of the quicker modules to prepare. Book it when you score 85% or more on three different full papers, which on a 24-question paper means no more than three or four wrong.

+Which Module 8 formulas should I learn?

Learn the lift and drag equations (in terms of dynamic pressure, wing area and coefficient), the load factor in a level turn (1 divided by the cosine of the bank angle), how stall speed rises with the square root of load factor, glide ratio equals lift over drag, and Mach number equals true airspeed over the local speed of sound.

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