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100+ Free EASA Module 16 Practice Questions

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2026 Statistics

Key Facts: EASA Module 16 Exam

76 questions

Module 16 exam (B1.2/B1.4/B3)

EASA Part-66 examination standard

95 minutes

Time allowed (B1.2/B1.4/B3)

EASA Part-66 examination standard

75%

Pass mark per module

EASA Part-66

3 options

Real exam multiple-choice format

EASA Part-66 examination standard

100LL is blue

AVGAS grade colour code

ASTM D910 / industry standard

12 June 2024

Regulation (EU) 2023/989 applicable date

Commission Implementing Regulation (EU) 2023/989

EASA Part-66 Module 16 (Piston Engine) is sat by aircraft maintenance licence candidates on the A2/A4, B1.2, B1.4 and B3 paths. The B1.2/B1.4/B3 paper is 76 three-option multiple-choice questions in 95 minutes (A2/A4: 52 questions, 65 minutes), with a 75% pass mark per module and roughly 75 seconds per question - no essays in Module 16. Content spans fundamentals (Otto four-stroke, two-stroke and diesel principles, compression ratio, displacement, efficiencies, firing order), engine performance (power, mixtures, leaning, detonation versus pre-ignition, altitude effects), construction (crankcase, crankshaft, camshaft, cylinders, pistons, valves, reduction gearbox), fuel systems (carburettors, icing, injection, FADEC), starting and ignition (magnetos, timing, plugs, impulse coupling), induction/exhaust/cooling, supercharging and turbocharging (wastegate, critical altitude), lubricants and fuels (AVGAS grades, oils), lubrication systems, engine indication, installation, ground operation and storage preservation. The syllabus follows Regulation (EU) 2023/989, applicable 12 June 2024; pre-2024 courses must finish under the old standard by 12 June 2026.

Sample EASA Module 16 Practice Questions

Try these sample questions to test your EASA Module 16 exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1In the four-stroke Otto cycle, during which stroke does the inlet valve open to admit the fuel/air charge into the cylinder?
A.Compression stroke
B.Induction (intake) stroke
C.Power (expansion) stroke
D.Exhaust stroke
Explanation: The Otto four-stroke sequence is induction, compression, power, exhaust. During the induction (intake) stroke the piston moves down and the inlet valve is open to draw the fuel/air charge into the cylinder.
2A cylinder has a total volume of 1000 cm3 with the piston at BDC and a clearance (combustion chamber) volume of 100 cm3 with the piston at TDC. What is the compression ratio?
A.9:1
B.10:1
C.11:1
D.100:1
Explanation: Compression ratio = total volume at BDC / clearance volume at TDC = 1000 / 100 = 10:1.
3Which efficiency expresses the ratio of brake horsepower delivered at the propeller shaft to the indicated horsepower developed in the cylinders?
A.Thermal efficiency
B.Volumetric efficiency
C.Combustion efficiency
D.Mechanical efficiency
Explanation: Mechanical efficiency = brake power / indicated power. It accounts for the power lost to friction and to driving accessories, typically 80-90% in a piston aero-engine.
4What is the firing order of a typical horizontally-opposed six-cylinder Lycoming aircraft engine (cylinders numbered 1-2-3-4-5-6)?
A.1-6-3-2-5-4
B.1-2-3-4-5-6
C.1-4-5-2-3-6
D.1-5-3-6-2-4
Explanation: The Lycoming horizontally-opposed six-cylinder firing order is 1-4-5-2-3-6. The 1-6-3-2-5-4 sequence is the Continental flat-six order; the two differ because Lycoming numbers its cylinders from the propeller end while Continental numbers from the accessory/rear end.
5In a two-stroke engine, one complete power cycle is produced for every:
A.Two revolutions of the crankshaft
B.Four revolutions of the crankshaft
C.One revolution of the crankshaft
D.Half a revolution of the crankshaft
Explanation: A two-stroke engine completes the full cycle (compression/ignition then power/exhaust) in one crankshaft revolution, giving one power stroke per revolution, unlike the four-stroke which needs two revolutions.
6Compared with the petrol Otto engine, the aircraft compression-ignition (diesel) engine ignites its fuel by:
A.A spark from a magneto-fired plug
B.A glow plug energised throughout running
C.The heat of air compressed to a high compression ratio
D.Pre-mixing fuel and air in a carburettor
Explanation: Compression-ignition (diesel) engines compress air to a high ratio (typically 16:1 or more), raising its temperature so that fuel injected near TDC ignites spontaneously without a spark.
7Volumetric efficiency of a normally-aspirated piston engine is best described as the:
A.Ratio of actual charge mass induced to the mass that would fill the swept volume at ambient conditions
B.Ratio of swept volume to clearance volume
C.Ratio of power output to fuel heat energy
D.Percentage of fuel completely burned in the cylinder
Explanation: Volumetric efficiency compares the actual mass (or volume) of charge drawn into the cylinder with the theoretical mass that would fill the swept volume at ambient density. It falls with altitude and high RPM due to flow restriction.
8The swept (piston displacement) volume of a single cylinder is calculated from:
A.Bore area multiplied by clearance height
B.Bore circumference multiplied by stroke
C.Bore area multiplied by stroke length
D.Total cylinder volume minus bore diameter
Explanation: Piston displacement (swept volume) = cross-sectional area of the bore (pi x r^2) multiplied by the stroke (distance from TDC to BDC). Total engine displacement multiplies this by the number of cylinders.
9During the valve overlap period of a four-stroke engine, near top dead centre at the end of the exhaust stroke:
A.The inlet valve has opened before the exhaust valve has closed
B.Both valves are fully closed
C.Only the exhaust valve is open
D.The ignition occurs to start combustion
Explanation: Valve overlap is the brief period around TDC between exhaust and induction when the inlet valve has already opened while the exhaust valve has not yet fully closed. It improves cylinder scavenging and charging at higher speeds.
10Thermal efficiency of a piston engine is most strongly increased by:
A.Reducing the compression ratio
B.Enriching the mixture well beyond stoichiometric
C.Lowering the cylinder operating temperature as far as possible
D.Increasing the compression ratio within detonation limits
Explanation: The ideal Otto-cycle thermal efficiency increases with compression ratio. Raising the compression ratio (up to the point where detonation occurs) extracts more work from each unit of fuel heat energy.

About the EASA Module 16 Exam

EASA Part-66 Module 16 (Piston Engine) is the powerplant knowledge module for aircraft maintenance engineers seeking a Category A2/A4, B1.2, B1.4 or B3 licence. It tests piston-engine fundamentals, construction and supporting systems - from the Otto four-stroke cycle and compression ratio through carburettors, fuel injection, magneto ignition, cooling, supercharging, lubrication, AVGAS, engine indication and ground operation. Examinations are three-option multiple-choice with a 75% pass mark per module, sat at a National Aviation Authority or an approved Part-147 organisation. The current syllabus follows Commission Implementing Regulation (EU) 2023/989, applicable from 12 June 2024.

Questions

76 scored questions

Time Limit

95 minutes (B1.2/B1.4/B3); 65 minutes for A2/A4

Passing Score

75% per module

Exam Fee

Approx. EUR 50-230 per module sitting (varies by NAA / Part-147 organisation) (EASA - examinations sat at National Aviation Authorities or approved Part-147 maintenance training organisations)

EASA Module 16 Exam Content Outline

22%

Fundamentals, Cycles & Performance

Otto four-stroke and two-stroke/diesel principles, compression ratio and piston displacement, mechanical/thermal/volumetric efficiency, firing order, mixtures and leaning, detonation versus pre-ignition, and altitude and manifold-pressure effects

18%

Engine Construction

Crankcase, crankshaft and counterweights/dampers, camshaft and valve mechanism with overlap and tappet clearance, cylinders, pistons and rings, connecting rods and plain bearings, accessory gearbox and propeller reduction gearbox

16%

Fuel Systems

Float and pressure carburettors, venturi and float chamber, accelerator pump and economiser, carburettor refrigeration icing and carb heat, continuous-flow and pressure fuel injection, flow divider, mixture/idle cut-off and piston FADEC

16%

Starting & Ignition

Magneto principle and E-gap, dual ignition and spark-plug heat range, ignition timing before TDC, impulse coupling for starting, P-lead earthing and the live-magneto hazard, magneto-to-engine timing and starter motor drives

16%

Induction, Exhaust, Cooling & Supercharging

Induction and alternate/hot air, air and liquid cooling with baffles, cowl flaps and thermostat, exhaust heat-exchanger and carbon-monoxide risk, backfire/afterfire, superchargers, turbochargers, wastegate, critical altitude and intercoolers

12%

Lubrication, Fuels, Indication & Operation

Wet and dry sump systems, pressure relief valve and oil-cooler thermostat, chip detectors, AVGAS grades and octane rating, multigrade oils, RPM/MAP/CHT/EGT and oil gauges, differential compression tests, run-up checks, trend monitoring and storage preservation

How to Pass the EASA Module 16 Exam

What You Need to Know

  • Passing score: 75% per module
  • Exam length: 76 questions
  • Time limit: 95 minutes (B1.2/B1.4/B3); 65 minutes for A2/A4
  • Exam fee: Approx. EUR 50-230 per module sitting (varies by NAA / Part-147 organisation)

Keys to Passing

  • Complete 500+ practice questions
  • Score 80%+ consistently before scheduling
  • Focus on highest-weighted sections
  • Use our AI tutor for tough concepts

EASA Module 16 Study Tips from Top Performers

1Memorise the four-stroke Otto order (induction, compression, power, exhaust) and practise compression-ratio calculations: ratio = total cylinder volume at BDC divided by clearance volume at TDC, not swept volume
2Learn to distinguish detonation (spontaneous explosion of end-gas after the spark) from pre-ignition (a hot spot igniting the charge before the spark) - exam distractors deliberately swap these
3Know the carburettor-icing envelope (about -7 C to +21 C with humid air, charge cooling of roughly 20-30 C) and the carb-heat check: a slight RPM drop then recovery confirms ice was present
4Understand the magneto P-lead safety logic: a broken earthing lead leaves the magneto live, so the engine may not stop and the propeller must always be treated as live unless P-leads are confirmed earthed
5Remember AVGAS colours and octane meaning: 100LL is blue, 100 is green, octane number rates anti-knock (detonation) resistance, not energy content
6For turbocharging, fix the key terms: the wastegate diverts exhaust around the turbine to set boost, and critical altitude is the highest altitude that still maintains rated manifold pressure

Frequently Asked Questions

What does EASA Part-66 Module 16 cover?

Module 16 (Piston Engine) covers piston-engine fundamentals, performance, construction and supporting systems: the Otto four-stroke cycle, compression ratio and displacement, carburettors and fuel injection, magneto ignition, induction, exhaust, cooling, supercharging and turbocharging, lubrication, AVGAS and oils, engine indication, installation, ground operation and storage preservation.

How many questions are on the Module 16 exam and how long is it?

For Category B1.2, B1.4 and B3 the Module 16 examination is 76 multiple-choice questions in 95 minutes. For Category A2 and A4 it is 52 questions in 65 minutes. Each question allows roughly 75 seconds. The pass mark is 75% per module.

Are the real EASA exam questions multiple-choice?

Yes. EASA Part-66 module examinations use three-option multiple-choice questions, each with a single correct answer. Essays were retained only in Module 7 after the June 2024 changes. This practice bank uses four options to add learning depth.

What is the pass mark and how many attempts are allowed?

The pass mark is 75% for the module. Candidates may sit a module up to three consecutive attempts, with a 90-day waiting period after three failed attempts, in line with EASA Part-66 examination rules at the approved organisation or NAA.

Which syllabus edition should I study for 2026?

Study to Commission Implementing Regulation (EU) 2023/989, applicable from 12 June 2024. Pre-2024 courses must be completed under the old standard by 12 June 2026. Note that the UK CAA has diverged post-Brexit, so keep your study EASA-specific.

Why does carburettor icing happen even on warm days?

Fuel vaporisation and the venturi pressure drop can cool the induction charge by roughly 20-30 C. With humid air at ambient temperatures from about -7 C to +21 C, this cooling can freeze moisture into ice in the carburettor, reducing power even on a warm, humid day.