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100+ Free PPL Aircraft General Knowledge Practice Questions

Pass your Sri Lanka CAA Private Pilot Licence (PPL) Aircraft General Knowledge & Principles of Flight Examination exam on the first try — instant access, no signup required.

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Sample PPL Aircraft General Knowledge Practice Questions

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

1Which structural loading type is characterized by forces that act to twist a structural member along its longitudinal axis?
A.Torsion
B.Compression
C.Shear
D.Tension
Explanation: Torsion occurs when a body is subjected to twisting forces, creating internal shear stresses. This loading is common in propeller shafts, engine drives, and control surfaces during aerodynamic deflection. The structural design must account for this to prevent twisting failures.
2In a semi-monocoque fuselage design, which components primary function is to resist the bending loads exerted on the structure?
A.Longerons and stringers
B.Formers and bulkheads
C.The stressed metal skin alone
D.Ribs and spars
Explanation: In semi-monocoque construction, longerons and stringers are longitudinal members that reinforce the skin and carry primary bending stresses. The skin is then attached to these members, sharing the loads rather than carrying them entirely on its own. Bulkheads and formers provide shape and resist vertical/transverse loads.
3How is the aerodynamic lift load distributed from the wing skin to the main wing spar in a conventional metal aircraft wing?
A.From the skin to the wing ribs, which then transfer the load to the wing spar
B.Directly from the skin to the spar via tension bolts, bypassing the ribs
C.Directly from the spar to the skin through compression struts
D.From the ribs directly to the longerons, bypassing the spar
Explanation: Aerodynamic lift acts directly on the wing skin. The skin transfers this pressure to the chordwise wing ribs, which maintain the wing profile, and the ribs then transfer these concentrated aerodynamic loads directly into the spanwise spar, which is the primary load-bearing member.
4What is the primary function of a shimmy damper installed on the nose landing gear assembly of a light aircraft?
A.To suppress high-frequency swiveling oscillations of the nosewheel during ground operations
B.To absorb vertical impact loads during hard landings and taxiing on rough terrain
C.To automatically center the nosewheel when the strut is fully compressed
D.To assist the pilot in steering the nosewheel through rudder pedal inputs
Explanation: A shimmy damper is a hydraulic shock absorber or friction device that dampens the rapid, destructive side-to-side oscillation (shimmy) of the nosewheel assembly during takeoff, landing, and taxiing. This ensures stable directional tracking and protects the nosegear structure from fatigue.
5If a hydraulic brake system has air bubbles trapped in the brake lines, what will be the symptom experienced by the pilot during braking?
A.A spongy brake pedal feel and reduced braking effectiveness
B.A rigid, unyielding brake pedal requiring excessive force to depress
C.An immediate lockup of the brakes upon slight pedal pressure
D.Brake fluid leaking directly from the master cylinder reservoir venting port
Explanation: Air is highly compressible, whereas hydraulic fluid is virtually incompressible. When air enters the brake lines, a portion of the pedal stroke is wasted in compressing the air bubble, resulting in a spongy or soft pedal feel and requiring pump-action or deeper travel to generate effective braking pressure.
6During the four-stroke cycle of a reciprocating piston engine, what is the valve overlap period?
A.The time when both the intake and exhaust valves are open simultaneously near top dead center
B.The duration when both valves are closed during the power and compression strokes
C.The overlap in timing between the ignition spark and the opening of the exhaust valve
D.The time window when two pistons are on the compression stroke at the same time
Explanation: Valve overlap is the brief period at the end of the exhaust stroke and the beginning of the intake stroke when both the intake and exhaust valves are open at the same time. This utilizes the inertia of the exiting exhaust gases to help pull in the fresh fuel-air charge (scavenging) and cool the cylinder.
7Which atmospheric conditions pose the highest risk for carburetor icing in a naturally aspirated light aircraft engine?
A.Ambient temperatures between -5°C and +20°C with high relative humidity
B.Dry air with ambient temperatures below -15°C at high altitudes
C.Ambient temperatures above +35°C with a relative humidity below 20%
D.Extremely cold ambient temperatures between -30°C and -20°C in clear air
Explanation: Carburetors are highly susceptible to icing when the relative humidity is high (above 50%) and the ambient temperature is between -5°C and +20°C. The adiabatic cooling of the air as it passes through the venturi, combined with the evaporation of fuel, can lower the internal temperature by up to 30°C, freezing any moisture present.
8What physical principles describe the flow of air through the venturi throat of a float-type carburetor?
A.Air velocity increases, causing a drop in static pressure and temperature
B.Air velocity decreases, causing an increase in static pressure and temperature
C.Air density increases, causing static pressure to rise and velocity to drop
D.Air velocity increases, causing static pressure to rise and temperature to drop
Explanation: According to Bernoulli's principle, as a fluid passes through a restriction (venturi throat), its velocity increases, which causes a corresponding decrease in static pressure. The pressure drop draws fuel from the discharge nozzle, and the expansion of the air causes an adiabatic temperature drop, which can freeze water vapor.
9What is the initial engine response when carburetor heat is applied to a light aircraft equipped with a fixed-pitch propeller, assuming carburetor ice is present?
A.An initial drop in RPM, followed by a gradual increase in RPM as the ice melts
B.An immediate, rapid surge in engine RPM followed by a sharp drop
C.No change in RPM initially, followed by a steady drop in cylinder head temperature
D.A continuous drop in RPM and severe engine roughness that persists until carburetor heat is turned off
Explanation: Applying carburetor heat routes hot, less-dense air from around the exhaust manifold into the engine, which immediately causes a slight drop in RPM due to the richer mixture. If ice is present, it melts and passes through the engine as water, causing temporary roughness, after which the RPM rises as normal airflow is restored.
10How does leaning the fuel-air mixture during a cruise flight affect the exhaust gas temperature (EGT) and cylinder head temperature (CHT)?
A.Both EGT and CHT will rise initially until reaching peak EGT, after which further leaning causes them to decrease
B.Both EGT and CHT will decrease continuously as the mixture is leaned
C.EGT will decrease immediately while CHT increases to its structural limit
D.EGT will rise continuously while CHT remains constant due to air cooling
Explanation: Leaning the mixture from a rich state increases the combustion temperature because there is less excess fuel to absorb heat, causing both EGT and CHT to rise. The temperatures reach a peak at the stoichiometric ratio (complete combustion), and leaning beyond this point (lean of peak) causes temperatures to fall because excess air acts as a cooling medium.

About the PPL Aircraft General Knowledge Exam

The Civil Aviation Authority of Sri Lanka (CAASL) Private Pilot Licence (PPL) Aircraft General Knowledge & Principles of Flight examination is a combined ground school assessment. It evaluates a candidate's understanding of aircraft structures, electrical and mechanical systems, engines, flight instruments, and the aerodynamic forces governing flight. The syllabus is closely aligned with EASA Part-FCL requirements, adapted for the Sri Lankan aviation regulatory environment. The examination is conducted as a computer-based test at the CAASL examination center located in Katunayake. It comprises 40 multiple-choice questions with a time limit of 1 hour and 15 minutes. To pass, candidates must achieve a score of at least 75%. Booking is done online through the CAASL licensing portal, and candidates must obtain a recommendation from their Approved Training Organization (ATO) prior to sitting the exam. Effective preparation requires a balance of mechanical system theory and aerodynamics. Candidates should focus on the operation of four-stroke engines, fuel and electrical systems, and pitot-static instruments, while also mastering flight stability, lift-producing devices, and stall characteristics. Utilizing practice question banks to simulate the exam format is highly recommended for building confidence and timing.

Questions

40 scored questions

Time Limit

1 hour and 15 minutes

Passing Score

75%

Exam Fee

LKR 1,000 (Civil Aviation Authority of Sri Lanka (CAASL) Examination Center)

PPL Aircraft General Knowledge Exam Content Outline

50%

Aircraft General Knowledge

Airframe structure, piston engines, electrical and fuel systems, instrumentation (pressure-sensitive, gyroscopic, magnetic).

50%

Principles of Flight

Subsonic aerodynamics, aerodynamic forces (lift, drag, thrust, weight), flight controls, stability, stalling and spinning.

How to Pass the PPL Aircraft General Knowledge Exam

What You Need to Know

  • Passing score: 75%
  • Exam length: 40 questions
  • Time limit: 1 hour and 15 minutes
  • Exam fee: LKR 1,000

Keys to Passing

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

PPL Aircraft General Knowledge Study Tips from Top Performers

1Master the operation and malfunctions of basic piston engine systems, including carburetor icing causes, magneto systems, and fuel-air mixture controls.
2Understand the mechanics of flight instruments: practice how pressure blocks affect altimeters, airspeed indicators, and vertical speed indicators.
3Thoroughly study aerodynamic stability: distinguish between static and dynamic stability, and know how the center of gravity limits affect both stall recovery and cruise efficiency.
4Review the forces acting on an aircraft during climbs, glides, turns, and stalls. Pay special attention to load factor changes in steep turns.

Frequently Asked Questions

What is the format and duration of the CAASL PPL Aircraft General Knowledge & Principles of Flight exam?

The exam is computer-based, consisting of 40 multiple-choice questions. Candidates are allocated 1 hour and 15 minutes to complete the combined paper.

Where is the CAASL examination conducted and how do I book it?

The CAASL examinations are conducted at the CAASL head office examination center in Katunayake, Sri Lanka. You can book the exam online through the CAASL licensing portal after receiving a recommendation from your CAASL-approved flying school.

What is the pass mark for the CAASL PPL exams?

The pass mark is 75%. For this 40-question exam, you must answer at least 30 questions correctly to pass.

How much does the CAASL PPL exam cost?

The exam fee is LKR 1,000 per subject sitting.

What happens if I fail a CAASL theoretical exam?

If you fail an exam, you must undergo further theoretical instruction at your Approved Training Organization (ATO) and obtain a new recommendation before registering to retake the exam.