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100+ Free EASA ATPL 021 AGK Practice Questions

Pass your EASA ATPL Theory - Aircraft General Knowledge: Airframe, Systems, Electrics and Powerplant (021) exam on the first try — instant access, no signup required.

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2026 Statistics

Key Facts: EASA ATPL 021 AGK Exam

80 questions

Exam length for subject 021

EASA AMC1 FCL.025 examination structure

2 hours

Time allowed for 021

EASA AMC1 FCL.025 examination structure

75%

Pass mark per ATPL subject

EASA Part-FCL

13 subjects

ATPL(A) theory exams after 090 Communications merge

EASA ED Decision 2019/017/R

18 months

Window to pass all ATPL theory subjects

EASA FCL.025

4 attempts / 6 sittings

Maximum attempts per subject and total sittings

EASA FCL.025

7 years

Validity of ATPL theory passes for licence issue

EASA Part-FCL

EASA ATPL 021 Aircraft General Knowledge (Airframe, Systems, Electrics, Powerplant) is one of 13 ATPL(A) theory exams. It is computer-based at a National Aviation Authority test centre: 80 single-best-answer multiple-choice questions in 2 hours, no negative marking, with a 75% pass mark. Questions come from the European Central Question Bank (current ECQB 2026 release, built on the 2020 syllabus). Content spans airframe structures, loads and the 1.5 safety factor, fail-safe and damage-tolerant design; hydraulics (3,000/5,000 psi, pumps, accumulators, PTU); landing gear, wheels, tyres and anti-skid brakes; primary/secondary flight controls and fly-by-wire control laws; pneumatics, air-cycle air conditioning and pressurisation; ice and rain protection; fuel systems; AC/DC electrics (115 V 400 Hz, IDG, TRU, batteries); piston engines (mixture, magnetos, propellers); turbine engines (EPR, EGT, N1/N2, compressor stall, thrust reverser, FADEC); the APU; and emergency equipment including oxygen, fire detection/extinguishing and GPWS. Under FCL.025, candidates have up to 4 attempts per subject, 6 sittings, and must pass all subjects within 18 months.

Sample EASA ATPL 021 AGK Practice Questions

Try these sample questions to test your EASA ATPL 021 AGK exam readiness. Each question includes a detailed explanation. Start the interactive quiz above for the full 100+ question experience with AI tutoring.

1A structure designed so that, after the failure of a single principal structural member, the remaining structure can carry the limit load without catastrophic failure, is described as:
A.Safe-life
B.Damage-tolerant
C.Fail-safe
D.Stiffness-critical
Explanation: A fail-safe structure has multiple or redundant load paths so that after the failure of one principal member, the remaining structure still carries limit load until the damage is detected and repaired.
2The limit load of an aircraft structure is defined as:
A.The load at which the structure fails completely
B.The maximum load expected in normal service operation
C.The limit load multiplied by the safety factor
D.The load that produces 50% permanent deformation
Explanation: Limit load is the maximum load anticipated in normal operation; the structure must withstand it without detrimental permanent deformation. Ultimate load (limit x 1.5 safety factor) is the load it must carry for at least 3 seconds without failure.
3In a semi-monocoque fuselage construction, the primary purpose of the longerons and stringers is to:
A.Carry torsional loads only
B.Provide the aerodynamic skin shape only
C.Carry pressurisation hoop stress
D.Carry bending and longitudinal (axial) loads
Explanation: In a semi-monocoque structure the stringers and longerons carry the longitudinal bending and axial loads, the frames maintain shape, and the skin carries shear and pressurisation hoop loads.
4Aircraft fatigue life is most directly affected by:
A.Steady cruise loads only
B.The number and magnitude of cyclic (fluctuating) loads
C.The static ultimate load applied once
D.Outside air temperature during cruise
Explanation: Fatigue is the progressive cracking caused by repeated cyclic loading well below the static strength; both the number of cycles and their amplitude determine fatigue life. Pressurisation cycles are a major contributor for the fuselage.
5In a hydraulic system, the component that converts hydraulic pressure into linear mechanical motion to move a flight control or landing gear is the:
A.Accumulator
B.Actuator (jack)
C.Reservoir
D.Filter
Explanation: An actuator (hydraulic jack) converts fluid pressure into linear (or rotary) mechanical movement, driving services such as flight controls, landing gear and flaps.
6The main purpose of a hydraulic accumulator is to:
A.Cool the hydraulic fluid
B.Remove air from the fluid
C.Store fluid under pressure, dampen pressure surges and provide an emergency reserve
D.Indicate fluid quantity in the reservoir
Explanation: An accumulator stores hydraulic fluid under pressure (against a gas charge, typically nitrogen), dampens pressure pulsations and surges from the pump, and can supply a short-term emergency reserve of pressurised fluid.
7A large modern transport aircraft hydraulic system typically operates at a nominal pressure of:
A.300 psi
B.3,000 psi
C.1,000 psi
D.10,000 psi
Explanation: Most large transport aircraft hydraulic systems operate at a nominal 3,000 psi (about 207 bar); some newer types (e.g. A380, B787) use 5,000 psi to reduce component size and weight.
8Which type of hydraulic fluid is most commonly used in large transport aircraft because of its fire resistance?
A.Mineral-based (red)
B.Vegetable-based (blue)
C.Phosphate-ester synthetic (e.g. Skydrol)
D.Silicone-based
Explanation: Large transport aircraft use phosphate-ester synthetic fluids (such as Skydrol) chiefly for their fire resistance and high-temperature stability. They are corrosive to paint and skin, so handling precautions are required.
9An anti-skid braking system protects against a locked wheel by:
A.Increasing brake pressure continuously until the wheel stops
B.Applying full brake pressure only on the upwind wheel
C.Disabling the brakes above 100 kt
D.Sensing impending wheel lock from wheel-speed deceleration and momentarily releasing brake pressure
Explanation: Anti-skid (anti-lock) systems monitor wheel-speed deceleration; when a wheel is about to skid (decelerating too rapidly relative to ground speed), pressure to that brake is momentarily released to restore rotation, maximising braking near the optimum slip ratio.
10A fusible plug fitted in a wheel hub is designed to:
A.Indicate tyre pressure electronically
B.Lock the wheel during parking
C.Melt and deflate the tyre if the wheel/brake overheats, preventing a burst
D.Detect a skidding wheel
Explanation: Thermal (fusible) plugs are made of a low-melting-point alloy; if brake heat raises the wheel temperature excessively, the plug melts and releases tyre pressure in a controlled way, preventing an explosive tyre burst.

About the EASA ATPL 021 AGK Exam

EASA ATPL(A) subject 021, Aircraft General Knowledge - Airframe, Systems, Electrics and Powerplant, is one of the 13 theoretical knowledge examinations required for the Airline Transport Pilot Licence (Aeroplanes). It is a computer-based multiple-choice exam of 80 questions in 2 hours, drawn from the European Central Question Bank (current release ECQB 2026). The subject covers aircraft structures and loads, hydraulics, landing gear and brakes, flight controls including fly-by-wire, pneumatics, air conditioning and pressurisation, ice and rain protection, fuel, electrics, piston and turbine engines, the APU and emergency equipment. A score of 75% is required to pass, with no negative marking.

Questions

80 scored questions

Time Limit

2 hours

Passing Score

75% per subject

Exam Fee

Varies by National Aviation Authority, approx EUR 60-130 per subject sitting (EASA via National Aviation Authorities (computer-based testing, commonly LPLUS TestStudio))

EASA ATPL 021 AGK Exam Content Outline

16%

Airframe, Structures, Loads & Materials

System design, limit and ultimate loads with the 1.5 safety factor, semi-monocoque construction with stringers carrying axial loads and skin carrying shear and hoop stress, fatigue and pressurisation cycles, fail-safe, safe-life and damage-tolerant design philosophies, and aluminium alloys versus carbon composites

20%

Hydraulics, Pneumatics, Air Conditioning & Pressurisation

3,000 and 5,000 psi hydraulic systems, variable-displacement pumps, accumulators and pre-charge, actuators, PTU and phosphate-ester (Skydrol) fluid, engine bleed air, air-cycle machine packs and water separators, outflow valve control, maximum differential pressure limits, negative pressure relief and the cabin altitude warning near 10,000 ft

20%

Landing Gear, Wheels, Tyres, Brakes & Flight Controls

Oleo-pneumatic shock struts, sequence valves, hydraulic nosewheel steering, weight-on-wheels (squat) switches, anti-skid braking, fusible plugs and carbon multi-disc brakes, primary controls (aileron/elevator/rudder), secondary controls (flaps, slats, spoilers, trimmable stabiliser), mass balance and flutter, and fly-by-wire control laws and protections

14%

Ice & Rain Protection and Fuel Systems

Thermal bleed-air leading-edge anti-ice versus pneumatic de-icing boots, electrical pitot/probe and windshield heat (also for bird-strike resistance), ice detectors, fuel tanks, centrifugal boost pumps, cross-feed, wing-bending relief fuel sequencing, the EU basic fuel scheme, fuel-tank inerting and water-contamination control

14%

Electrics

AC and DC generation, 115 V 400 Hz, integrated drive generators and constant speed drives, transformer rectifier units, nickel-cadmium and lead-acid batteries with thermal-runaway awareness, essential/hot busbars and load shedding, circuit breakers, semiconductors and diodes, static inverter, ram air turbine and bonding/static dischargers

16%

Piston & Turbine Powerplant

Four-stroke Otto cycle, mixture and altitude leaning, carburettor icing, magneto ignition, constant-speed and feathering propellers, gas-turbine architecture and twin-spool engines, high-bypass turbofan thrust, EPR, EGT, N1/N2, compressor stall/surge and variable vanes, thrust reverser, FADEC, oil systems and the APU

How to Pass the EASA ATPL 021 AGK Exam

What You Need to Know

  • Passing score: 75% per subject
  • Exam length: 80 questions
  • Time limit: 2 hours
  • Exam fee: Varies by National Aviation Authority, approx EUR 60-130 per subject sitting

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 ATPL 021 AGK Study Tips from Top Performers

1Memorise the 021 exam logistics: 80 questions in 2 hours, 75% pass mark, no negative marking, so attempt every question and pace yourself at about 90 seconds each
2Understand limit versus ultimate load and the 1.5 safety factor, and be able to distinguish fail-safe, safe-life and damage-tolerant structural design philosophies
3Know standard system numbers: transport hydraulics at 3,000 psi (5,000 psi on A380/B787), AC at 115 V 400 Hz, and the cabin altitude warning near 10,000 ft
4Be clear on anti-ice versus de-ice: thermal bleed-air anti-ice runs continuously, while pneumatic boots cyclically inflate to shed accreted ice on turboprops
5Drill turbine parameters: EPR is turbine-discharge over inlet total pressure, EGT approximates turbine gas temperature, N1 is the LP (fan) spool and N2 the HP spool
6Learn why centre-tank fuel is burned first to keep wing fuel for wing-bending relief, and how cross-feed and boost pumps maintain engine supply

Frequently Asked Questions

How many questions are on the EASA ATPL 021 exam and how long is it?

Subject 021 Aircraft General Knowledge (Airframe, Systems, Electrics, Powerplant) has 80 single-best-answer multiple-choice questions and a time allowance of 2 hours. There is no negative marking, so it is best to answer every question.

What is the pass mark for ATPL 021?

The pass mark is 75%, the same as for all EASA ATPL theoretical knowledge subjects. You must achieve at least 75% in each of the 13 ATPL(A) theory subjects to complete the theory requirement.

What topics does ATPL 021 cover?

It covers airframe and structures, hydraulics, landing gear, wheels, tyres and brakes, flight controls including fly-by-wire, pneumatics, air conditioning and pressurisation, ice and rain protection, fuel systems, electrics, piston and turbine engines, the APU, and emergency equipment such as oxygen and fire protection. Instrumentation is a separate subject (022).

Is 021 the same as the Instrumentation exam (022)?

No. Aircraft General Knowledge is split into two separate exams: 021 covers airframe, systems, electrics and powerplant, while 022 covers instrumentation, automatic flight and electronic displays. They are sat as distinct papers.

How many attempts and how much time do I have to pass the ATPL theory exams?

Under FCL.025 you are allowed a maximum of 4 attempts per subject and 6 examination sittings overall, and you must pass all subjects within 18 months from the end of the calendar month of your first attempt.

How long are ATPL theory passes valid?

A completed set of ATPL(A) theoretical knowledge passes is valid for 7 years for the issue of an ATPL, counted from the validity of an instrument rating or the relevant licence as defined in Part-FCL.

What is the ECQB and which edition applies in 2026?

The European Central Question Bank (ECQB) is the common pool of exam questions used across EASA states. The current release is ECQB 2026, a content refresh built on the 2020 ATPL learning-objective syllabus, so question counts and durations are unchanged.