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EASA Part-66 Module 17 Cats A1 · A2 · B1.1 · B1.2 · B1.E · B3

Propeller EASA Part-66 — Module 17 Practice Questions

Module 17 covers propeller theory, construction, pitch control, synchronising, ice protection and maintenance — sat by piston-aeroplane and turboprop candidates (A1/A2, B1.1, B1.2, B3). Below: what's covered, exam format, and seven sample questions in the same style you'll meet on exam day.

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803
Questions in bank
5
Syllabus sections
40 min
Exam time (B1/B2)
75 %
EASA pass mark

Syllabus at a glance

Full Module 17 syllabus

Practise one chapter at a time. Module 17 breaks into 7 syllabus chapters, and subscribers can drill any one of them on its own — ten questions from that chapter and nothing else. Useful when you have just studied a single topic and want to know whether it went in, rather than sitting a whole-module quiz. Open the module and choose By chapter.

Section 17.1-17.2
Fundamentals & Construction
  • Blade element theory, angle of attack & relative airflow
  • Aerodynamic, centrifugal & thrust forces (CTM, ATM)
  • Wooden, composite & metal propeller construction
  • Fixed, controllable & constant-speed types
Section 17.3
Pitch Control
  • Mechanical & electrical pitch-change methods
  • Constant-speed unit (CSU) operation & governing
  • Feathering, reverse pitch & beta range
  • Overspeed protection & pitch stops
Section 17.4
Synchronising
  • Master/slave engine RPM matching
  • Synchrophasing & blade phase angle
  • Pulse probes & actuator-driven trim
Section 17.5
Ice Protection
  • Fluid anti-icing — slinger rings & isopropyl alcohol
  • Electrical de-icing boots & slip rings
  • Cyclic timers & fast/slow icing modes
Section 17.6-17.7
Maintenance & Storage
  • Static & dynamic balancing, blade tracking
  • Blending damage, erosion, corrosion & delamination
  • Cropping limits & repair schemes (Level 3 for B1.1/B1.2/B3)
  • Preservation & storage requirements

Three classic exam-day traps

CTM vs ATM direction

Centrifugal Turning Moment drives blades to fine pitch; Aerodynamic Turning Moment drives them to coarse. Windmilling reverses the picture — ATM then assists CTM rather than opposing it.

Left-handed propeller viewpoint

Rotation is always defined from behind the engine looking forward. A left-handed prop turns anticlockwise from the rear — which means clockwise when viewed from the front, the reverse of intuition.

Anti-icing vs de-icing fluid

Propeller fluid systems use isopropyl alcohol, not ethylene glycol (that's wing/tail) and not ethyl alcohol. Candidates often pick the wrong alcohol because all three sound interchangeable.

What Module 17 covers — in plain English

Module 17 of the EASA Part-66 syllabus covers everything the licensed engineer needs to know about propellers — from the blade-element aerodynamics that produce thrust through to the constant-speed units, governors, ice-protection systems and balancing procedures that keep them serviceable. It is one of the more practical modules: most of the failure modes you study here have a direct, visible counterpart on the flight line, which is why section 17.6 (Maintenance) is examined at knowledge level 3 for B1.1, B1.2 and B3 candidates while everything else sits at level 2. Static and dynamic balancing, blade tracking, blending damage and cropping limits all appear regularly in the question bank, and unlike the more theoretical modules the wrong answers tend to look very plausible to anyone who hasn't spent time on a hangar floor.

The bulk of the exam pressure comes from pitch control — speeder springs, flyweights, on-speed/under-speed/overspeed conditions, feathering circuits, reverse pitch and the beta range. Many questions hinge on small details: which way CTM and ATM try to move the blade, what holds the prop on the fine-pitch stop, how the CSU governor reacts to a change in TAS, and which oil supply feeds the pitch servo in single-acting versus double-acting designs. The synchronising and synchrophasing sections add a second layer — distinguishing matched RPM from matched phase angle, and remembering that synchrophasing uses pulse probes feeding a single phase-angle controller while basic synchronising only trims a slave engine's governor to match the master. Ice-protection questions are simpler but catch candidates out on the alcohol type (isopropyl, not ethyl or glycol) and on fast/slow cycle timing.

Module 17 only applies to candidates whose licence scope includes propeller-driven aircraft: A1 and A2 (piston aeroplanes), B1.1 (turbine aeroplanes), B1.2 (piston aeroplanes) and B3 (piston aeroplanes ≤ 2000 kg). B2 avionics and B1.3/B1.4 helicopter candidates do not sit this paper under the 2023/989 amendment (B1.3 was removed entirely, and the small B2 carve-out for 17.1/17.2 at level 1 was dropped). Candidates renewing from a pre-2024 licence should pay particular attention to the new category split — A2 and B1.2 now sit at level 2 across all sections (previously level 1), so the question style aimed at those candidates has shifted from pure recognition towards applied understanding of the systems. The full per-section knowledge-level breakdown, including the level-3 Maintenance carve-out and the storage/preservation section that's often skipped in revision, is on our Module 17 syllabus page.

These samples are drawn from our live Module 17 question bank of 803 questions. The full timed practice quiz draws 32 questions per attempt (or 20 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 Fundamentals · Blade Theory

The primary purpose of propeller is to

  1. A change engine horsepower to thrust.
  2. B provide static and dynamic stability to aircraft.
  3. C create lift on the fixed aerofoils of an aircraft.
Reveal answer + explanation Hide answer
Correct answer: A — change engine horsepower to thrust.
A propeller is an aerofoil that converts the rotational shaft power produced by the engine into forward thrust. It contributes nothing to aircraft stability, and the lift on fixed aerofoils (wings, tailplane) comes from forward airspeed, not the propeller itself.
Q2 Construction · Blade Geometry

The thrust face of a propeller blade is the

  1. A root to which the gear segment is fitted.
  2. B blade face or flat side.
  3. C blade back or curved side.
Reveal answer + explanation Hide answer
Correct answer: B — blade face or flat side.
The thrust face (or pressure face) is the flat side of the blade, facing aft in normal rotation. The cambered side facing forward is the blade back, analogous to the upper surface of a wing — same Bernoulli pressure differential, just rotated 90°.
Q3 Pitch Control · Reverse Pitch

The purpose of using reverse pitch propellers is to

  1. A provide aerodynamic breaking.
  2. B allow aircraft to taxi backwards.
  3. C reverse the direction of rotation of the propeller.
Reveal answer + explanation Hide answer
Correct answer: A — provide aerodynamic breaking.
Reverse pitch swings the blade angle through zero into a negative angle so the propeller produces rearward thrust — used as aerodynamic braking on landing roll. The shaft still rotates the same way; only the blade angle reverses. Taxiing backwards is a side-effect, not the design purpose.
Q4 Pitch Control · Pitch Stops

The purpose of fine pitch stop is to

  1. A maintain constant speed in flight.
  2. B prevent the propeller moving below flight fine pitch in flight.
  3. C maintain maximum RPM at takeoff.
Reveal answer + explanation Hide answer
Correct answer: B — prevent the propeller moving below flight fine pitch in flight.
The flight fine-pitch stop blocks the blade from going finer than the minimum in-flight angle. Without it, a CSU failure could let the blade drive to ground-fine in cruise — overspeeding the engine. The stop is mechanically withdrawn on the ground to allow reverse/ground-fine selection.
Q5 Synchronising · Synchrophasing

A propeller synchrophasing system allows a pilot to reduce noise and vibration by

  1. A setting the RPM of all propellers exactly the same.
  2. B adjusting the plane of rotation of all propellers.
  3. C adjusting the phase angle between the propellers.
Reveal answer + explanation Hide answer
Correct answer: C — adjusting the phase angle between the propellers.
Synchronising matches RPM; synchrophasing goes one step further by setting a fixed angular offset between corresponding blades on each engine. The offset is tuned so the pressure peaks from each propeller don't arrive at the cabin in phase, cutting cabin drum noise significantly.
Q6 Ice Protection · Fluid Systems

Propeller fluid anti-icing systems generally use which of the following?

  1. A Ethyl alcohol.
  2. B Ethylene glycol.
  3. C Isopropyl alcohol.
Reveal answer + explanation Hide answer
Correct answer: C — Isopropyl alcohol.
Propeller fluid systems pump isopropyl alcohol (IPA) to a slinger ring on the hub; centrifugal force flings it down the leading edge of each blade. Ethylene glycol is used on wings and stabilisers but is too viscous and corrosive for propeller slinger rings.
Q7 Maintenance · Blade Repair

Removal of material from the propeller blade tips, resulting in a reduction in propeller diameter is called

  1. A tipping.
  2. B cropping.
  3. C topping.
Reveal answer + explanation Hide answer
Correct answer: B — cropping.
Cropping is the controlled removal of material at the tip to repair damage or restore a clean profile. Each propeller type has a maximum cropping limit published in its maintenance manual — cropping beyond that limit changes blade-element performance and renders the propeller unserviceable.
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Module 17 — frequently asked questions

How many questions are in the EASA Part-66 Module 17 exam?
The number of multiple-choice questions depends on your licence category. Category A candidates (A1/A2) answer 20 questions, while Category B1 candidates (B1.1/B1.2) answer 32 questions. The B1 paper is longer because it examines the propeller syllabus in greater depth, including the level-3 Maintenance section.
What is the pass mark for EASA Part-66 Module 17?
The pass mark is 75%, the same threshold that applies to every EASA Part-66 module. You must reach 75% correct on the multiple-choice paper to pass; each question has three options with a single correct answer. Aim comfortably above the line, because a handful of the plausible-looking distractors in this module — especially on pitch control and ice-protection fluids — are easy to pick by mistake.
How long is the Module 17 exam?
Category A candidates get 25 minutes for their 20-question paper, and Category B1 candidates get 40 minutes for their 32-question paper. Both work out to roughly 75 seconds per question, which is enough time to read each stem carefully and eliminate the distractors before answering.
Which EASA licence categories require Module 17?
Module 17 applies only to propeller-driven aircraft categories: A1, A2, B1.1, B1.2 and B3. B2 avionics and B1.3/B1.4 helicopter candidates do not sit this paper. If your licence scope does not include propeller aeroplanes, Module 17 is not part of your syllabus.
What does Module 17 cover, and what do students find hardest?
Module 17 covers propeller fundamentals and construction, pitch control (constant-speed units, feathering, reverse pitch and the beta range), synchronising and synchrophasing, ice protection, and maintenance and storage. The hardest area is pitch control, where candidates confuse the Centrifugal Turning Moment (which drives blades to fine pitch) with the Aerodynamic Turning Moment (which drives them to coarse). Two other classic traps catch people out: propeller rotation is always defined from behind the engine looking forward, and propeller fluid anti-icing uses isopropyl alcohol rather than ethyl alcohol or ethylene glycol. Because most failure modes here have a direct hangar-floor counterpart, the wrong answers look very plausible.
How should I revise for EASA Part-66 Module 17?
Focus your effort on pitch control, since that is where most of the exam pressure sits — work through CSU governing, feathering, reverse pitch and the fine-pitch stop until they are second nature, and drill the CTM-versus-ATM direction until you never hesitate. Learn the synchronising and synchrophasing distinction (matched RPM versus matched phase angle) and nail the ice-protection alcohol type. Do not skip the level-3 Maintenance section on balancing, blade tracking and cropping limits, which the B1 paper examines heavily. The best preparation is timed practice against exam-style questions so you get used to spotting the plausible distractors quickly.
Can I practise in a language other than English?

Yes. Every quiz question, all of its answer options and the written explanation can be read in 13 languages besides English — Chinese (Traditional), French, German, Greek, Hindi, Italian, Norwegian, Polish, Portuguese, Romanian, Russian, Spanish and Turkish. It is included for every signed-in member at no extra cost, and you can switch language in the middle of a quiz without losing your answers or your timer.

The English original stays one click away on every question, which is the point: the EASA Part-66 examination is sat in English, so you can read a question in your own language, answer it, then switch it back to English to check yourself against the wording you will actually meet.

Two caveats worth knowing. It is machine translation — checked so that no two answer options drift into meaning the same thing and that numerals and units survive intact, but it is not a human technical translation. And technical designations such as A320, LEAP-1A, Part-145, CS-25 and ATA chapter numbers are deliberately left in English, because those are the strings on the aircraft, in the manual and on the exam paper. Translation covers the quizzes; the study notes and reference pages are in English.

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Module 17 study resources

Module 17 detailed syllabus
Per Commission Regulation (EU) 2023/989
Module 17 study notes
Topic-by-topic explanations
Free Module 17 study notes: 17.1 Fundamentals
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Q&A Forum
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EASA licence categories
A · B1 · B2 · B2L · B3 overview

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