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EASA Part-66 Module 12 Cats A3 · A4 · B1.3 · B1.4

Helicopter Aerodynamics, Structures & Systems EASA Part-66 — Module 12 Practice Questions

Module 12 is the helicopter-specific counterpart to Module 11, sat only by rotary-wing licence candidates. It covers rotor aerodynamics, swashplate and tail-rotor control, main gearbox and freewheel units, airframe construction and the systems that keep a helicopter airborne. Seven sample questions sit below.

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Every question comes with a worked, EASA-grounded explanation — understand why, don't just memorise.
1 279
Questions in bank
5
Syllabus sections
160 min
Exam time (B1/B2)
75 %
EASA pass mark

Syllabus at a glance

Full Module 12 syllabus
Section 12.1
Rotary Wing Aerodynamics
  • Rotor disc, tip path plane, advancing & retreating blade
  • Torque reaction, dissymmetry of lift & gyroscopic precession
  • Ground effect, translational lift & autorotation
  • Vortex ring state, blade stall & Coriolis effect
Section 12.2
Flight Control Systems
  • Swashplate: rotating & non-rotating stars
  • Collective, cyclic & tail-rotor pitch control
  • Mixing units, servo & hydraulic boost
  • SAS, autopilot, AFCS & trim systems (B1.3/B1.4)
Section 12.4
Transmissions
  • Main, intermediate & tail rotor gearboxes
  • Freewheel units — sprag & roller clutches
  • Rotor brakes, drive shafts, couplings & hangers
  • Chip detectors, HUMS & over-torque procedures
Section 12.5
Airframe Structures
  • Fuselage, tailboom & pylon construction
  • Rotor head — hub, grips, dampers, elastomeric bearings
  • Rotor blade construction (spars, skins, honeycomb)
  • Damage tolerance, safe-life & fatigue concepts
Section 12.12
Hydraulic Power
  • Single, dual & utility/flight system architecture
  • Pumps, reservoirs, accumulators & filters
  • Servo actuators for flight controls
  • Manual reversion & system monitoring

Three classic exam-day traps

Gyroscopic precession — 90° phase lag

Candidates know the rotor disc tilts but forget the input must be applied 90° before the desired reaction. Cyclic pitch peaks one quarter-turn ahead of where the blade actually flaps.

Articulated rotor head hinges

A fully articulated head has flapping, drag (lead-lag) and feathering hinges. Delta hinges belong on semi-rigid heads; mixing them into the articulated list is a classic distractor.

Collective vs cyclic confusion

Collective changes all blade pitch equally for vertical thrust; cyclic changes pitch once per revolution to tilt the disc. Swap them under exam pressure and the answer is always wrong.

What Module 12 covers — in plain English

Module 12 of the EASA Part-66 syllabus is the helicopter-only sister of Module 11 and is examined exclusively for the rotary-wing licence categories: A3, A4, B1.3 and B1.4. Candidates working towards a fixed-wing licence (A1, A2, B1.1, B1.2, B2) do not sit this paper. The module is large — covering rotor aerodynamics, swashplate control, main and tail gearboxes, airframe construction, and every aircraft system from hydraulics and fuel to fire protection, electrical power and avionics — which is why the B1 exam runs to 128 questions over 160 minutes.

The hardest sections at first sitting tend to be the aerodynamics theory (12.1) and the transmission and rotor head chapters (12.4 and 12.5). Rotary-wing physics has no equivalent in fixed-wing training, so candidates often arrive without intuition for gyroscopic precession, dissymmetry of lift, translational lift, autorotation or vortex ring state. Add the mechanical complexity of a freewheel unit, sprag clutch, elastomeric rotor head bearings and a multi-stage main gearbox, and the volume of new vocabulary alone catches many candidates out.

Category A3/A4 candidates sit a shorter paper (100 questions, 125 minutes) at knowledge level 1 or 2 across most sections — broadly recognition and basic explanation. B1.3 and B1.4 candidates sit the full knowledge level 3 paper on the bulk of the systems (flight controls, transmissions, hydraulics, fuel, fire, electrical, instruments, landing gear and lights), meaning they must be able to diagnose, apply and describe operation in detail. The full per-section knowledge level breakdown is on our Module 12 syllabus page.

These samples are drawn from our live Module 12 question bank of 1 279 questions. The full timed practice quiz draws 128 questions per attempt (or 100 for Cat A), scored against the official EASA 75 % pass mark, with weak-area tracking across attempts.

7 free sample questions

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Q1 Rotary Wing Aerodynamics · Lift

Helicopter rotor blades create lift by

  1. A pushing the air down.
  2. B working like a screw.
  3. C creating low pressure above the blades.
Reveal answer + explanation Hide answer
Correct answer: C — creating low pressure above the blades.
A rotor blade is an aerofoil — the pressure differential between the lower surface (higher static pressure) and the upper surface (lower static pressure) generates lift, exactly as on a fixed wing. Mass-flow downwash is a consequence of that lift, not its cause.
Q2 Rotary Wing Aerodynamics · Lift

Lift generated by a blade is proportional to the

  1. A relative airflow and the angle of attack.
  2. B aircraft airspeed and angle of attack.
  3. C relative airflow and the pitch.
Reveal answer + explanation Hide answer
Correct answer: A — relative airflow and the angle of attack.
Lift depends on the relative airflow seen by the blade (a combination of rotational speed and induced/translational components) and the angle of attack — the angle between that relative airflow and the chord line. Pitch is the geometric blade angle and only equals AoA in a vacuum.
Q3 Flight Control Systems · Swashplate

What is the swash plate on a helicopter used for?

  1. A Control of the pitch of the rotor blades.
  2. B Control of the speed of the rotor blades.
  3. C Control of the flap of the rotor blades.
Reveal answer + explanation Hide answer
Correct answer: A — Control of the pitch of the rotor blades.
The swashplate translates non-rotating cyclic and collective inputs from the pilot into rotating pitch changes at each blade via pitch links. It does not control rotor speed (that is the engine/governor) nor flap (that is the natural response of the disc to dissymmetry of lift).
Q4 Flight Control Systems · Collective

Movement of the collective control will

  1. A increase the pitch of the main rotor blades.
  2. B increase the pitch of the tail rotor.
  3. C tilt the disc and increase engine power.
Reveal answer + explanation Hide answer
Correct answer: A — increase the pitch of the main rotor blades.
The collective lever raises the entire swashplate, applying an equal pitch change to all main rotor blades simultaneously. That changes total rotor thrust for climb or descent. Cyclic, by contrast, tilts the swashplate to vary blade pitch once per revolution and tilt the disc.
Q5 Transmissions · Clutch & Freewheel

The clutch on a piston helicopter is positioned

  1. A between the engine and the engine reduction gearbox.
  2. B between the engine reduction gearbox and the main rotor gearbox.
  3. C between the main rotor gearbox and the rotor head.
Reveal answer + explanation Hide answer
Correct answer: B — between the engine reduction gearbox and the main rotor gearbox.
On a piston helicopter the clutch sits between the engine reduction gearbox and the main rotor gearbox so the engine can be started and warmed without driving the rotors, then engaged smoothly. The freewheel unit downstream lets the rotor keep turning if the engine stops, enabling autorotation.
Q6 Airframe Structures · Rotor Head

A fully articulated rotor head would incorporate

  1. A flapping hinges, feathering hinges and delta hinges.
  2. B flapping hinges, delta hinges and drag hinges.
  3. C feathering hinges, drag hinges and flapping hinges.
Reveal answer + explanation Hide answer
Correct answer: C — feathering hinges, drag hinges and flapping hinges.
A fully articulated head has three independent hinges per blade: flapping (vertical motion to relieve dissymmetry of lift), drag/lead-lag (in-plane motion to absorb Coriolis effect) and feathering (pitch change for cyclic and collective input). Delta hinges belong on semi-rigid heads.
Q7 Hydraulic Power · Manual Reversion

In the event of hydraulic failure in a power control system, a requirement of the manual reversion is that it must be

  1. A possible, but not recommended.
  2. B automatic and instantaneous.
  3. C operated by the standby hydraulic system.
Reveal answer + explanation Hide answer
Correct answer: B — automatic and instantaneous.
Reversion to manual control on hydraulic failure must be automatic and instantaneous — the pilot cannot be expected to perform a deliberate changeover while still flying the helicopter. The certification standards (CS-27/CS-29) require continuous controllability through the failure transient.
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Module 12 — frequently asked questions

How many questions are in the EASA Part-66 Module 12 exam?
The number depends on your licence category. Category A3/A4 candidates sit 100 multiple-choice questions, while Category B1.3/B1.4 candidates sit the fuller paper of 128 multiple-choice questions. The two papers differ because the B1 exam is tested at a higher knowledge level across the systems chapters.
What is the pass mark for EASA Part-66 Module 12?
The pass mark is 75%, the same threshold EASA sets for every Part-66 module. You must answer at least 75% of the questions correctly to pass, and there is no penalty deducted for a wrong answer, so it always pays to attempt every question rather than leave it blank.
How long is the Module 12 exam?
Category A3/A4 candidates are allowed 125 minutes for their 100-question paper, while Category B1.3/B1.4 candidates are allowed 160 minutes for their 128-question paper. Both work out to roughly one and a quarter minutes per question, so time is generous provided you keep a steady pace.
Which EASA licence categories require Module 12?
Module 12 is the helicopter-specific module and is sat only by the rotary-wing categories: A3, A4, B1.3 and B1.4. Fixed-wing candidates working towards A1, A2, B1.1, B1.2 or B2 do not take this paper — they sit Module 11 instead.
What does Module 12 cover, and what do students find hardest?
Module 12 covers rotary-wing aerodynamics, flight control systems including the swashplate, transmissions, airframe structures and hydraulic power. The aerodynamics theory catches many candidates out because rotary-wing physics has no fixed-wing equivalent — gyroscopic precession requires the cyclic input to be applied 90° before the desired disc reaction, which is easy to get wrong under exam pressure. The other classic traps are confusing collective (equal pitch change to all blades) with cyclic (pitch varied once per revolution), and mixing delta hinges into the fully articulated rotor head's flapping, drag and feathering hinges.
How should I revise for Module 12?
Focus first on the aerodynamics and rotor head chapters, since these carry the concepts with no fixed-wing parallel — be sure you can explain dissymmetry of lift, translational lift, autorotation and vortex ring state in your own words. Get the mechanical vocabulary straight too: a fully articulated head has flapping, drag (lead-lag) and feathering hinges, and the freewheel unit lets the rotor keep turning for autorotation if the engine stops. Working through practice questions on this page is the fastest way to expose the collective-versus-cyclic and precession phase-lag mistakes before exam day.

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Module 12 study resources

Module 12 detailed syllabus
Per Commission Regulation (EU) 2023/989
Module 12 study notes
Topic-by-topic explanations
Q&A forum
Ask about tricky Module 12 questions
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