EASA Part-66 Powerplant Exam FAQ: Modules 14, 15, 16 & 17
The propulsion modules are the engine core of the EASA Part-66 B1 licence: Module 14 (Propulsion), Module 15 (Gas Turbine Engine), Module 16 (Piston Engine), and Module 17 (Propeller). They cover the theory, construction, operation, and maintenance of aircraft engines — both turbine and piston — along with their supporting systems and propellers. This FAQ addresses the most common questions about module content, exam format, study strategies, and how Skylicence Europe can accelerate your preparation.
Skylicence Europe Team
EASA Part-66 exam preparation specialists — helping engineers earn their Part-66 licence since 2025
Overview of the EASA Part-66 Propulsion Modules
The propulsion modules are the engine knowledge requirements of the EASA Part-66 licence, defined in Annex III to Regulation (EU) No 1321/2014. Together with the airframe modules, they form the technical foundation of the B1 (mechanical) licence categories. Module 14 provides the core propulsion overview for all B1 categories, while Modules 15, 16 and 17 deepen the turbine, piston, and propeller knowledge required by the specific category — with depth levels 1, 2 and 3 defined in Appendix I of Part-66.
One of the unique aspects of the propulsion syllabus is its dual-engine-type requirement. A B1.1 candidate must master turbine engine theory in depth while still passing the piston engine module, and a B1.2 candidate focused on piston aircraft must still master turbine engine theory at the required level. A candidate headed toward a career on light piston aircraft must still understand turbine hot-section inspections, and an engineer focused on turbine airline maintenance must still understand magneto timing and carburettor icing. This breadth makes comprehensive study essential. Skylicence Europe addresses this by providing separate adaptive tracking for turbine and piston content, ensuring balanced proficiency across both engine types.
The real-world importance of the propulsion modules cannot be overstated. Engines are among the most critical systems on any aircraft from a safety perspective, and engine maintenance forms a large portion of a certifying engineer's daily work. The knowledge tested here — from cylinder compression check procedures to turbine engine hot section inspection limits — is knowledge you will use throughout your career. Skylicence Europe reinforces this practical connection by including scenario-based questions that describe actual maintenance situations and ask you to apply your propulsion knowledge, not just recall facts.
Turbine vs. Piston: A Balanced Curriculum
The propulsion modules divide content between turbine and piston engines. Piston engine topics in Module 16 include engine theory (four-stroke Otto cycle operation), construction (crankcase, cylinders, pistons, rings, valves, camshaft), ignition systems (magnetos, spark plugs, leads), fuel metering systems (carburettors, fuel injection), lubrication, cooling, and engine storage. Turbine engine topics in Module 15 include engine theory (Brayton cycle, gas generator), construction (compressor types — axial and centrifugal, combustion chambers, turbine sections), fuel control systems, ignition (exciters, igniters), lubrication, and thrust management (reverse thrust, thrust augmentation). Module 17 propeller systems — which bridge both engine types — form their own significant exam with a dedicated quota.
Frequently Asked Questions
What is the EASA Part-66 powerplant content and which modules cover it?
Under Regulation (EU) No 1321/2014, Annex III (Part-66), engine and propeller knowledge is examined through four modules defined in Appendix I. Module 14 (Propulsion) provides the core overview for all B1 categories. Module 15 (Gas Turbine Engine) covers turbine engine theory, construction, and maintenance in depth — required for B1.1 (aeroplane turbine) applicants at level 3. Module 16 (Piston Engine) covers reciprocating engines in depth for B1.2 (aeroplane piston), B1.3 and B1.4 (helicopter) applicants. Module 17 (Propeller) covers propeller theory, construction, and maintenance for B1.1 and B1.2. Skylicence Europe covers every Appendix I subject area for these modules with practice questions organised by engine type and system.
How many questions are on the propulsion module exams and what is the pass mark?
Each Part-66 module has a set question quota and time limit, and every module exam has a 75 percent pass mark (66.A.25). For the propulsion modules: Module 14 has 60 questions in 75 minutes, Module 15 has 108 questions in 135 minutes, Module 16 has 60 questions in 75 minutes, and Module 17 has 48 questions in 60 minutes. Module exams are computer-based and administered by approved maintenance training organisations (MTOs). Skylicence Europe offers timed practice exams that match the exact quota and duration of each module, with adaptive difficulty that adjusts as your skills improve.
What are the most important topics in the propulsion modules?
The most heavily tested topics include: turbine engine theory and operation (Brayton cycle, gas generator sections, thrust production); turbine engine construction (compressor types — axial and centrifugal, combustion chambers, turbine sections, exhaust systems); reciprocating engine theory and operation (four-stroke cycle, valve timing, ignition timing, power calculations); reciprocating engine construction (crankcase, crankshaft, connecting rods, pistons, rings, valves, camshaft); engine fuel metering systems (carburettors and fuel injection for piston engines, fuel control units for turbines); ignition systems (magneto-based for piston engines, exciter/igniter for turbines); lubrication systems (wet sump, dry sump, oil types, oil analysis); and propellers (fixed-pitch, constant-speed, feathering, reversing) in Module 17.
Do I need to know both piston and turbine engines equally?
It depends on your licence category. A B1.1 (aeroplane turbine) candidate must master Module 15 in depth and also pass Module 16 (piston) and Module 17 (propeller) at the required depth levels, because the Part-66 licence is issued for the whole category. A B1.2 (aeroplane piston) candidate must master Module 16 in depth and still pass Module 15. Many engineers with experience on one engine type neglect the other during study — a common mistake, since the exams for your category cover both. Skylicence Europe divides the engine content into turbine and piston sections with separate adaptive difficulty tracking so you can build proficiency in both at your own pace.
What specific engine systems are most heavily tested?
Engine fuel metering systems and ignition systems receive the most attention. For piston engines, you need to understand carburettor types (float-type, pressure-type), fuel injection systems (continuous flow, direct injection), and the effects of mixture control on engine performance. Magneto ignition — including magneto construction, timing, impulse couplings, and magneto-to-engine timing procedures — is a frequently tested topic. For turbine engines, you need to understand fuel control unit functions (hydromechanical and electronic), fuel manifolds and nozzles, and ignition systems (exciters, igniter plugs, high-energy versus low-energy ignition). Propeller systems — particularly constant-speed propellers, governors, feathering, reversing, and synchronising — are also heavily represented in Module 17.
How much engine instrument knowledge is required?
Engine instruments are a significant topic across the propulsion modules. You should understand the operating principles of the major engine instruments: tachometers (mechanical, electrical, electronic), manifold pressure gauges, oil temperature and pressure gauges, cylinder head temperature gauges, exhaust gas temperature gauges, fuel flow meters, and torque meters for turbine engines. For each instrument, know what it measures, how it works, normal operating ranges, and what abnormal readings indicate about engine condition. Turbine engine instruments — including EGT, N1, N2, and N3 indicators, fuel flow, vibration monitoring, and oil debris monitoring — are increasingly emphasised on modern module exams.
What should I know about propellers (Module 17)?
Module 17 (Propeller) is a distinct and important exam. You need to understand propeller theory (angle of attack, blade pitch, thrust, torque, efficiency), fixed-pitch propellers and their ground-adjustable variants, and constant-speed propellers — the most common type on exam questions. Constant-speed propeller operation, including the propeller governor, speeder spring, flyweights, pilot valve, and pitch change mechanism, is essential knowledge. You should also understand feathering and unfeathering systems, reversing propellers for turbine aircraft, propeller synchronising and synchrophasing, propeller ice protection, and propeller inspection criteria — including blade damage limits, track checks, and hub inspection requirements.
Are the propulsion modules harder than the airframe modules?
Opinions vary, but many engineers find the propulsion modules somewhat more focused than the airframe modules. While the airframe modules span dozens of subject areas covering many different aircraft systems, the propulsion modules concentrate on one primary system — the engine and its supporting systems — plus propellers. This narrower focus means less context-switching during study. However, the propulsion material is conceptually deeper: you need to understand thermodynamic cycles, combustion, and the detailed internal construction of engines. Candidates who struggle with theoretical concepts may find Module 15 particularly challenging. Skylicence Europe offers explanatory content and progressive difficulty to help you build understanding from fundamentals to advanced topics.
What types of lubrication systems are covered?
Lubrication systems are a core topic covering both wet-sump (oil in a sump integral to the engine) and dry-sump (oil stored in a separate tank) systems. For each type, you should understand the components — oil pumps (gear-type, gerotor), oil filters (full-flow, bypass, screen), oil coolers (air-cooled, fuel-cooled), oil pressure relief valves, and oil temperature regulation. You should know the properties of aviation oils (viscosity grades, additives, detergent versus non-detergent) and how to select the correct oil for different engine types and operating conditions. Oil analysis and the interpretation of oil consumption trends as diagnostic tools are also tested, along with lubrication system maintenance — oil changes, filter inspections, and identification of contamination such as fuel dilution and metal particles.
How should I study for the propulsion modules?
The most effective study strategy starts with mastering the theory of operation for the engine type at the heart of your category. Without a solid understanding of the four-stroke cycle or the Brayton cycle, you will struggle with system-level questions. Once you understand the basic engine cycles, study each supporting system individually — fuel, ignition, lubrication, cooling, and propeller. Focus on how each system interacts with the engine and with other systems. Finally, practise with integrated troubleshooting scenarios that require diagnosing problems across multiple systems. Use the Part-66 Appendix I syllabus as your checklist and approved EASA training material as your primary reference. Skylicence Europe supports this layered approach with topic-level adaptive difficulty and mixed-system mock exams.
Are there questions about specific engine models in the module exams?
The Part-66 module exams evaluate general propulsion knowledge, not model-specific details. You will not be asked about a specific fuel nozzle part number for a Pratt & Whitney PT6 versus a GE CF34. Instead, the exams cover principles that apply across engine types — how a turbine engine fuel control unit works in general, what happens during a hot start, how to inspect a propeller blade for damage, or what engine instruments indicate in various failure scenarios. However, you should be familiar with representative engines used across the European fleet, such as the Lycoming O-360, Continental IO-520 (piston), Pratt & Whitney PT6, and Honeywell TPE331 (turbine). Skylicence Europe questions reference these representative engines to connect general principles to real-world applications.
How does Skylicence Europe help me prepare for the propulsion modules?
Skylicence Europe offers 4,464 EASA Part-66 practice questions across all 17 modules, with dedicated engine coverage for Modules 14, 15, 16 and 17. Key features include AI-powered adaptive difficulty that adjusts to your performance for turbine and piston topics separately, detailed explanations for every answer choice, timed mock exams matching the real question quotas and time limits, and performance analytics that show your accuracy by engine type and system. The platform supports both focused subject study and integrated mock exams. One licence category is free on the FREE plan — start practising on your schedule.
For more information about the other EASA Part-66 module exams, check out our airframe module exam FAQ and the EASA Part-66 study guide. Visit the main Skylicence Europe FAQ for platform-related questions.
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