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CPL Aircraft General Knowledge practice questions

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Question 1Aircraft general knowledge (airframe, systems and powerplants)

On an aircraft with a constant-speed propeller, what is the primary function of the propeller governor?

  1. It feathers the blades automatically after every shutdown
  2. It synchronises the engine-driven fuel pump with throttle movement
  3. It limits manifold pressure during descent
  4. It maintains the selected RPM by varying oil pressure to the propeller hub Correct answer.

Explanation

The governor senses engine RPM and meters oil pressure to the propeller hub, changing blade angle so that RPM stays at the value selected with the propeller control. It does not govern manifold pressure or fuel flow, and feathering is normally commanded by the pilot.

Question 2Aircraft general knowledge (airframe, systems and powerplants)

In a semi-monocoque wing structure, what is the main role of the wing skin?

  1. It carries a large share of the bending and torsional loads together with the internal structure Correct answer.
  2. It acts solely as a fuel tank boundary
  3. It only provides an aerodynamic fairing and carries no structural load
  4. It transfers all loads directly to the spar caps through the ribs

Explanation

Semi-monocoque construction relies on the skin working with stringers, ribs and spars to resist bending and torsion, which is why skin thickness and fastener integrity are structurally significant. A pure fairing role would describe non-structural or fabric covering.

Question 3Aircraft general knowledge (airframe, systems and powerplants)

What is the purpose of the bypass ratio in a turbofan engine?

  1. It expresses the fuel flow compared with the airflow through the combustor
  2. It expresses the fan pressure ratio compared with the compressor pressure ratio
  3. It expresses the turbine inlet temperature compared with the compressor outlet temperature
  4. It expresses the mass flow through the fan duct compared with the mass flow through the core Correct answer.

Explanation

Bypass ratio is the ratio of air mass flow passing through the bypass duct to that passing through the engine core. High bypass ratios improve propulsive efficiency and reduce specific fuel consumption at typical cruise speeds.

Question 4Aircraft general knowledge (airframe, systems and powerplants)

During a normal pre-flight inspection, hydraulic fluid in the reservoir sight glass should be checked with the system

  1. depressurised with all actuators manually stroked to their limits
  2. depressurised and the actuators in their normal at-rest position Correct answer.
  3. pressurised with the parking brake released and flight controls at full deflection
  4. fully pressurised with the gear retracted

Explanation

Reservoir level is checked with the system depressurised and components in their normal static position so that the reading can be compared with the marked servicing band. Pressurised or displaced actuators transfer fluid into the lines and give a misleadingly low indication.

Question 5Aircraft general knowledge (airframe, systems and powerplants)

What is the function of a fuel-oil heat exchanger on a turbine engine?

  1. It cools the fuel and warms the oil to reduce oil viscosity at altitude
  2. It pressurises the fuel to the burner nozzles
  3. It separates water from the fuel by centrifugal action
  4. It warms the fuel and cools the engine oil, helping to prevent fuel filter icing Correct answer.

Explanation

The fuel-oil heat exchanger uses hot engine oil to raise fuel temperature, which reduces the risk of ice blocking the fuel filter, while simultaneously cooling the oil. Water separation and fuel pressurisation are handled by other components.

Question 6Aircraft general knowledge (airframe, systems and powerplants)

Which statement correctly describes the effect of dihedral on lateral static stability?

  1. It produces a rolling moment that increases an existing sideslip, giving negative lateral static stability
  2. It produces a rolling moment that opposes a sideslip, giving positive lateral static stability Correct answer.
  3. It increases longitudinal stability but destabilises the aircraft directionally
  4. It has no effect on lateral stability and only changes the stall speed

Explanation

When the aircraft sideslips, the lower wing meets the airflow at a higher effective angle of attack than the raised wing, so it produces more lift and the resulting roll tends to level the wings. This restoring moment is positive lateral static stability.

Question 7Aircraft general knowledge (airframe, systems and powerplants)

What does the red radial line on an engine tachometer indicate?

  1. The idle RPM for the engine
  2. The RPM at which the propeller governor engages
  3. The maximum permissible continuous RPM Correct answer.
  4. The RPM for best economy cruise

Explanation

The red radial line marks the maximum RPM approved for continuous operation; exceeding it risks overspeed damage. Other markings such as the green arc and yellow arc show the normal and caution ranges.

Question 8Aircraft general knowledge (airframe, systems and powerplants)

In a light aircraft electrical system, what is the purpose of the voltage regulator in the charging circuit?

  1. It disconnects the battery from the bus during engine start
  2. It limits the current drawn by the starter motor
  3. It converts alternating current to direct current
  4. It controls alternator field current to hold charging voltage within limits Correct answer.

Explanation

The voltage regulator varies the field current of the alternator so that system voltage stays within a safe band, protecting the battery and avionics from over-voltage. Rectification is done by the alternator diodes and starting current is controlled by the starter circuit.

Question 9Aircraft general knowledge (airframe, systems and powerplants)

An aircraft is cruising at a constant altitude when the pilot selects a higher propeller RPM. Assuming the throttle is unchanged, what happens to manifold pressure?

  1. It decreases because the engine breathes more air per unit time at higher RPM Correct answer.
  2. It increases because the governor opens the wastegate
  3. It increases because the propeller loads the engine more heavily
  4. It remains exactly constant because the throttle position is fixed

Explanation

At a fixed throttle setting, increasing RPM increases the volume of air drawn through the induction system each minute, which lowers manifold pressure. This is why manifold pressure must be re-set after an RPM change.

Question 10Aircraft general knowledge (airframe, systems and powerplants)

Why is a turbine engine typically more tolerant of a sudden full-throttle acceleration than a reciprocating engine?

  1. The fuel is injected directly into the turbine rather than the combustor
  2. The compressor is driven by the propeller rather than by the turbine
  3. The fuel control schedules acceleration to stay within compressor surge and turbine temperature limits Correct answer.
  4. The turbine has no moving parts that can be damaged by rapid acceleration

Explanation

Turbine fuel controls incorporate acceleration scheduling so that fuel flow increases in step with compressor speed, avoiding surge and excessive turbine gas temperature. Uncontrolled fuel delivery during a slam acceleration could cause a surge or a hot start.

Question 11Aircraft general knowledge (airframe, systems and powerplants)

A landing gear shock strut is found to have insufficient extension after servicing. Which condition best explains this?

  1. The strut has been under-serviced with hydraulic fluid and has excessive nitrogen pressure
  2. The strut has been over-serviced with hydraulic fluid and has insufficient nitrogen charge Correct answer.
  3. The brake lines have been bled with the gear retracted
  4. The torque links have been over-tightened, preventing extension

Explanation

Correct servicing requires the strut to be filled with fluid to the specified level and then charged with nitrogen to the correct pressure. Too much fluid and too little gas leave insufficient gas volume to support the aircraft, so the strut sits compressed.

Question 12Aircraft general knowledge (airframe, systems and powerplants)

During a climb at a constant indicated airspeed with full throttle, the pilot observes that the mixture must be leaned progressively. What is the main reason?

  1. The carburettor heat valve opens automatically as altitude increases
  2. The engine oil becomes thinner, increasing fuel flow through the fuel pump
  3. Fuel density decreases with altitude, so more fuel volume is needed for the same mass
  4. Air density decreases with altitude, so the fuel-air mixture becomes richer unless fuel flow is reduced Correct answer.

Explanation

As altitude increases, air density falls faster than fuel density, so a carburettor or fuel control set for sea level delivers an over-rich mixture. Leaning restores the correct fuel-air ratio and improves combustion efficiency.

Question 13Aircraft general knowledge (airframe, systems and powerplants)

What is the purpose of the torque links (scissors) on a nose landing gear assembly?

  1. They provide the main structural attachment of the gear to the airframe
  2. They transmit braking torque to the wheel axle
  3. They damp shimmy oscillations during taxi
  4. They keep the wheel aligned with the strut while allowing the strut to compress and extend Correct answer.

Explanation

The torque links connect the lower axle assembly to the upper strut so that steering inputs are transmitted while the strut remains free to slide in and out. Shimmy damping is provided by a separate damper, and the gear attachments carry the primary loads.

Question 14Aircraft general knowledge (airframe, systems and powerplants)

A pilot selects carburettor heat during cruise and the RPM rises slightly. What does this indicate?

  1. The engine is detonating and heat is reducing the detonation
  2. The throttle valve has been opened further by the heat control linkage
  3. The carburettor was icing and the heat melted the ice
  4. The mixture was over-rich and carburettor heat leaned it towards a more efficient ratio Correct answer.

Explanation

Carburettor heat warms and expands the incoming air, which enriches the mixture; a slight RPM rise therefore suggests the engine was running lean of the optimum rather than rich. A rough-running engine that smooths with heat is the classic sign of carburettor icing.

Question 15Aircraft general knowledge (airframe, systems and powerplants)

In a pressurised aircraft, what is the function of the outflow valve?

  1. It modulates the rate at which cabin air leaves the aircraft to control cabin altitude and differential pressure Correct answer.
  2. It controls the temperature of the bleed air entering the cabin
  3. It admits fresh air from the engine bleed system into the cabin
  4. It relieves excessive pressure in the hydraulic reservoir

Explanation

Cabin pressure is regulated by controlling how fast air escapes through the outflow valve while bleed air flows in continuously. The valve therefore sets both cabin altitude and the pressure differential across the fuselage.

Question 16Aircraft general knowledge (airframe, systems and powerplants)

Why does an aircraft with a swept wing tend to have a lower critical Mach number penalty than a straight wing?

  1. The sweep reduces the chordwise component of the free-stream velocity over the wing Correct answer.
  2. The sweep lowers the wing loading at high speed
  3. The sweep removes the need for a supercritical aerofoil
  4. The sweep increases the wing area exposed to the free stream

Explanation

Only the component of airflow perpendicular to the leading edge is effective in generating lift, so sweeping the wing reduces the chordwise velocity and delays the onset of local supersonic flow. This raises the critical Mach number and postpones drag rise.

Question 17Aircraft general knowledge (airframe, systems and powerplants)

What is the purpose of a compressor bleed valve on a gas turbine engine?

  1. It cools the turbine blades during take-off
  2. It drains fuel from the combustor after shutdown
  3. It releases excess air from the compressor during low-speed operation to prevent compressor surge Correct answer.
  4. It supplies air to the cabin pressurisation system at all power settings

Explanation

At low rotational speeds the rear compressor stages cannot accept the air delivered by the front stages, so a bleed valve vents some air to keep the compressor within its stable operating range. Closing the valve at higher speed allows full airflow through the engine.

Question 18Aircraft general knowledge (airframe, systems and powerplants)

An aircraft with a tricycle landing gear is being taxied on a slope. Which statement about the nosewheel steering is correct?

  1. Steering authority increases as weight is transferred off the nosewheel
  2. Nosewheel steering is only effective when the parking brake is set
  3. Steering authority is reduced when weight is transferred off the nosewheel Correct answer.
  4. Nosewheel steering remains independent of nosewheel loading

Explanation

Steering force depends on the friction between the nosewheel tyre and the surface, which is proportional to the load on that wheel. On a slope or during acceleration the nosewheel unloads, so steering authority falls.

Question 19Aircraft general knowledge (airframe, systems and powerplants)

What is the primary purpose of a firewall in an engine compartment?

  1. It forms the aerodynamic cowling around the engine
  2. It isolates the engine compartment from the rest of the aircraft to contain a fire Correct answer.
  3. It reduces engine noise transmitted to the cabin
  4. It provides structural support for the engine mounts

Explanation

The firewall is a fire-resistant bulkhead that prevents flames and hot gases from reaching the cabin or other vulnerable areas. It may also carry engine mountings, but its defining function is fire containment.

Question 20Aircraft general knowledge (airframe, systems and powerplants)

A constant-speed propeller is set to a low RPM for descent and the aircraft accelerates. What does the governor do to maintain the selected RPM?

  1. It decreases blade angle to reduce drag and prevent overspeed
  2. It increases blade angle to absorb more power and prevent overspeed Correct answer.
  3. It feathers the blades to limit RPM
  4. It opens the throttle automatically to match the RPM

Explanation

As airspeed rises the propeller tends to windmill faster, so the governor increases blade angle to raise the load on the engine and hold RPM at the selected value. Decreasing blade angle would increase RPM further.

Question 21Aircraft general knowledge (airframe, systems and powerplants)

Why must the fuel selector be positioned so that both tanks feed in some light twin-engine aircraft during certain phases of flight?

  1. To ensure fuel is available to both engines if one tank becomes unusable Correct answer.
  2. To equalise fuel temperature between the tanks
  3. To increase the octane rating of the fuel
  4. To reduce the fuel pressure at the injectors

Explanation

With a crossfeed or both-tanks selection, a failure or blockage affecting one tank does not starve both engines as long as the surviving tank can supply them. This improves the reliability of the fuel supply in critical phases.

Question 22Aircraft general knowledge (airframe, systems and powerplants)

An aircraft is in a steady level turn at a bank angle of 60 degrees. By what factor is the load factor increased compared with straight-and-level flight?

  1. 1.41
  2. 2.0 Correct answer.
  3. 3.0
  4. 1.15

Explanation

Load factor in a level turn equals one divided by the cosine of the bank angle. For 60 degrees, cosine is 0.5, so the load factor is 2.0, meaning the wing must produce twice the lift to maintain altitude.

Question 23Aircraft general knowledge (airframe, systems and powerplants)

In a turbocharged reciprocating engine, what is the function of the wastegate?

  1. It vents excess fuel back to the tank when boost is high
  2. It limits oil flow to the turbocharger bearings
  3. It regulates exhaust gas flow through the turbocharger turbine to control boost pressure Correct answer.
  4. It bypasses the intercooler at low power settings

Explanation

The wastegate is a valve in the exhaust path that bypasses the turbine. By opening or closing it, the controller varies the energy extracted by the turbine and therefore the boost produced by the compressor.

Question 24Aircraft general knowledge (airframe, systems and powerplants)

An aircraft suffers a complete alternator failure in flight with a serviceable battery. Which electrical load management is most appropriate?

  1. Leave all equipment on and rely on the battery until landing
  2. Shed non-essential loads and keep navigation, communication and essential instruments powered Correct answer.
  3. Reset the alternator field repeatedly to restore output
  4. Turn off all electrical equipment to preserve the battery completely

Explanation

With the battery as the only source, endurance is limited, so non-essential loads are switched off to extend the time available for essential avionics and lighting. Repeated field resets are inappropriate for a failed alternator and may worsen the fault.

Question 25Aircraft general knowledge (airframe, systems and powerplants)

Why is a supercritical aerofoil able to delay drag rise at high subsonic Mach numbers?

  1. It reduces the wing thickness ratio to zero at the tip
  2. It increases the camber to raise the local velocity over the wing
  3. It flattens the upper-surface pressure distribution to weaken the shock wave that forms Correct answer.
  4. It removes the need for wing sweep on high-speed aircraft

Explanation

A supercritical section uses an extended region of favourable pressure and aft camber to reduce peak local velocity, which weakens and moves the shock wave rearward. The result is a higher drag-rise Mach number for a given thickness ratio.

Question 26Aircraft general knowledge (airframe, systems and powerplants)

On a light aircraft with a fixed-pitch propeller, what happens to engine RPM when the aircraft enters a prolonged climb at full throttle compared with level flight?

  1. RPM increases because the thinner air reduces drag on the propeller blades at altitude
  2. RPM remains exactly constant because the propeller pitch is fixed and cannot change
  3. RPM decreases because the propeller load increases as the aircraft slows and the blade angle of attack rises Correct answer.
  4. RPM decreases only if the mixture is leaned, otherwise it stays constant

Explanation

With a fixed-pitch propeller the blade angle is constant, so when airspeed falls in a climb the propeller's angle of attack and therefore its load increase. The engine cannot reach the same RPM at full throttle, so RPM decreases as the aircraft slows. This is why climb performance is limited compared with level flight.

Question 27Aircraft general knowledge (airframe, systems and powerplants)

Which component transmits the engine's torque to the wheels of a light aircraft during ground operation through a reduction gear arrangement?

  1. The propeller shaft directly to the wheels
  2. The vacuum pump drive pad
  3. The engine crankshaft via the reduction gearbox and drive train Correct answer.
  4. The starter motor through the flywheel ring gear

Explanation

Engine power reaches the propeller through the crankshaft, and in many light aircraft a separate drive train with a reduction gearbox transmits torque to the wheels for taxiing. The crankshaft is the source of torque, with gearing used to match speed and torque to the wheels. Accessory drives such as the vacuum pump pad do not transmit propulsion torque.

Question 28Aircraft general knowledge (airframe, systems and powerplants)

What is the primary function of the empennage in a conventional light aircraft?

  1. To house the fuel tanks for the engine
  2. To provide longitudinal and directional stability and control Correct answer.
  3. To reduce the aircraft's empty weight by replacing fuselage structure
  4. To increase the wing aspect ratio for better climb

Explanation

The empennage comprises the horizontal and vertical stabilisers plus their control surfaces. It provides pitch (longitudinal) and yaw (directional) stability and carries the elevator and rudder for control. It does not store fuel or replace fuselage structure.

Question 29Aircraft general knowledge (airframe, systems and powerplants)

In a light aircraft fuel system, what is the purpose of the fuel strainer or filter fitted between the tank and the carburettor?

  1. To increase fuel pressure before the carburettor
  2. To separate water from the fuel by centrifugal action
  3. To measure the fuel flow for the cockpit gauge
  4. To trap contaminants and prevent them reaching the carburettor jets Correct answer.

Explanation

The fuel strainer or filter is placed in the supply line to trap dirt, rust and other debris before it can block the small carburettor jets. Blocked jets would cause a lean mixture and possible engine stoppage. Water separation is normally handled by a separate drainable sump.

Question 30Aircraft general knowledge (airframe, systems and powerplants)

Which statement best describes the purpose of the engine cowling on a light aircraft?

  1. To increase the engine's compression ratio at high altitude
  2. To act as the primary structural member carrying wing loads
  3. To store lubricating oil for the engine
  4. To streamline the engine installation and direct cooling air over the cylinders Correct answer.

Explanation

The cowling smooths airflow around the engine, reducing drag, and shapes and directs cooling air through the cylinder fins. It also protects the engine from the elements. It is not a primary load-bearing structure and does not store oil.

Question 31Aircraft general knowledge (airframe, systems and powerplants)

What does the green arc on an engine tachometer typically indicate?

  1. The range in which takeoff power may be used
  2. The normal operating range for continuous cruising Correct answer.
  3. The range in which the engine must be shut down
  4. The idle range below which the engine may stall

Explanation

Colour coding on engine tachometers follows a standard convention. The green arc marks the normal operating range for continuous operation, while a red line marks the maximum permitted RPM and a yellow arc may mark a caution range. Takeoff power is normally limited by time, not by a separate arc.

Question 32Aircraft general knowledge (airframe, systems and powerplants)

In a reciprocating engine, what is the function of the magneto?

  1. To supply a high-voltage spark to the spark plugs at the correct time Correct answer.
  2. To regulate the fuel-air mixture delivered to the cylinders
  3. To generate the low-voltage current used to charge the battery
  4. To drive the oil pump through the accessory gear train

Explanation

A magneto is a self-contained ignition device that generates high voltage and distributes it to the spark plugs at the correct point in the engine cycle. Because it generates its own current, the engine can continue to run without the aircraft's electrical system. It does not charge the battery or meter fuel.

Question 33Aircraft general knowledge (airframe, systems and powerplants)

What is the purpose of the dihedral angle incorporated into the wings of many light aircraft?

  1. To reduce the wing bending moment in turbulence
  2. To increase the maximum cruise speed
  3. To improve lateral static stability in a sideslip Correct answer.
  4. To allow the wing to be built with fewer ribs

Explanation

Dihedral gives the wing a positive angle relative to the lateral axis, so a sideslip produces a rolling moment that tends to level the wings. This improves lateral static stability. It does not increase cruise speed or reduce bending loads.

Question 34Aircraft general knowledge (airframe, systems and powerplants)

During a pre-flight inspection a pilot finds that the tyre on the main landing gear is worn so that the fabric is visible through the tread. What is the correct action?

  1. The tyre may be used provided the pressure is increased
  2. The aircraft must not be flown until the tyre is replaced Correct answer.
  3. The tyre may be used if the wear is on the outboard side only
  4. The aircraft may be flown if the flight is short and at low speed

Explanation

Exposed fabric indicates that the tread has worn through, so the tyre no longer meets airworthiness requirements and could fail under load. The aircraft must not be dispatched until the tyre is replaced. Increased pressure or a short flight does not restore the tyre's structural integrity.

Question 35Aircraft general knowledge (airframe, systems and powerplants)

A pilot notices that the ammeter shows a constant discharge in flight after start. Which condition most likely explains this?

  1. The battery is fully charged and the charging current has dropped to zero
  2. The voltage regulator is limiting the charging rate correctly
  3. The starter relay has remained engaged after start
  4. The alternator has failed and the battery is supplying the electrical loads Correct answer.

Explanation

A continuous discharge with the engine running indicates that the charging source is not supplying current, so the battery is carrying the loads and will eventually be depleted. This is typical of an alternator or generator failure. A fully charged battery would show a near-zero charge, not a discharge.

Question 36Aircraft general knowledge (airframe, systems and powerplants)

In a fuel-injected reciprocating engine, what is the function of the fuel distributor?

  1. To separate air bubbles from the fuel supply
  2. To cool the fuel before it reaches the injectors
  3. To meter fuel to each cylinder in sequence and in the correct quantity Correct answer.
  4. To pressurise the fuel tank for positive feed

Explanation

The distributor receives metered fuel from the fuel control unit and divides it among the individual cylinder injectors in the correct firing sequence. It does not cool the fuel, pressurise the tank or remove air bubbles. Proper distribution ensures each cylinder receives the correct mixture.

Question 37Aircraft general knowledge (airframe, systems and powerplants)

An aircraft is descending with the throttle closed and the engine at low power. What is the main reason carburettor ice is more likely in this condition?

  1. The mixture is rich, which lowers the freezing point of the fuel
  2. The fuel flow is high, which cools the fuel further
  3. The throttle butterfly causes a large pressure drop and strong cooling of the air Correct answer.
  4. The engine oil is cooler so the carburettor body is colder

Explanation

With a partly or fully closed throttle the pressure drop across the butterfly is large, which sharply cools the air and promotes ice formation from moisture in it. Fuel vaporisation adds further cooling. Carburettor ice is therefore most likely at low power settings such as descent.

Question 38Aircraft general knowledge (airframe, systems and powerplants)

What is the purpose of the constant-speed propeller governor's pilot valve?

  1. To measure the manifold pressure for the cockpit gauge
  2. To feather the propeller automatically on engine failure
  3. To direct oil flow to or from the propeller hub to change blade angle Correct answer.
  4. To limit the maximum engine RPM mechanically

Explanation

The pilot valve is the control element of the governor. It senses flyweight force against a speeder spring and directs oil to or from the propeller hub so that blade angle changes to hold the selected RPM. It does not measure manifold pressure or feather the propeller automatically.

Question 39Aircraft general knowledge (airframe, systems and powerplants)

During a run-up check, the pilot selects each magneto in turn and observes a normal small RPM drop on both. What does this confirm?

  1. The engine is developing full takeoff power
  2. The fuel mixture is set correctly for takeoff
  3. Both magnetos are functioning and the ignition timing is approximately correct Correct answer.
  4. The propeller governor is operating correctly

Explanation

The magneto check confirms that each magneto is producing a spark and that the engine continues to run on either one. A normal small drop shows both are serviceable and reasonably timed. It does not measure power output, mixture setting or propeller governor operation.

Question 40Aircraft general knowledge (airframe, systems and powerplants)

What is the function of the oil cooler bypass valve in a reciprocating engine lubrication system?

  1. To keep the oil at a suitable temperature by routing it around the cooler when cold Correct answer.
  2. To filter metal particles from the oil
  3. To supply oil to the propeller governor
  4. To increase oil pressure at high altitude

Explanation

The bypass valve opens when the oil is cold and viscous, routing oil around the cooler so that it warms up quickly and pressure is not excessive. As the oil warms, the valve closes and oil flows through the cooler. It does not filter the oil or supply the governor.

Question 41Aircraft general knowledge (airframe, systems and powerplants)

An aircraft with a turbocharged engine is climbing and the pilot observes that manifold pressure is falling below the selected value. Which action is appropriate?

  1. Reduce RPM to decrease the turbocharger speed
  2. Close the wastegate to increase exhaust flow to the turbine Correct answer.
  3. Lean the mixture to increase exhaust temperature
  4. Open the wastegate further to increase exhaust flow to the turbine

Explanation

If manifold pressure falls below the selected value, the turbocharger is not producing enough boost, so the wastegate should be closed to send more exhaust gas through the turbine. This increases turbine and compressor speed and restores boost. Opening the wastegate would reduce boost further.

Question 42Aircraft general knowledge (airframe, systems and powerplants)

What is the main purpose of the firewall-mounted shutoff valve in a fuel system?

  1. To balance fuel between the left and right tanks
  2. To allow the pilot to stop fuel flow to the engine in an emergency Correct answer.
  3. To drain water from the fuel tanks
  4. To regulate the fuel pressure at the carburettor

Explanation

A firewall shutoff valve lets the pilot cut off fuel to the engine, for example in the event of an engine fire or a fuel leak. It is a safety device, not a pressure regulator or water drain. Fuel balancing is done with the selector valve.

Question 43Aircraft general knowledge (airframe, systems and powerplants)

A pilot reports that the landing gear warning horn sounds when the throttle is retarded in flight. Which condition is the most likely cause?

  1. The gear warning circuit is isolated by the squat switch on the ground
  2. The gear is retracted and the throttle is below the warning threshold Correct answer.
  3. The gear horn is designed to sound only on the ground
  4. The gear is extended and locked down

Explanation

The landing gear warning system is designed to alert the pilot when the throttle is retarded towards idle with the gear not down and locked. A horn in flight with the throttle retarded therefore suggests the gear is retracted. With the gear down and locked the warning should be inhibited.

Question 44Aircraft general knowledge (airframe, systems and powerplants)

What is the purpose of the static dischargers fitted to the trailing edges of an aircraft's control surfaces?

  1. To provide a lightning path to the ground
  2. To reduce flutter by adding trailing-edge mass
  3. To reduce the accumulation of static electricity and improve radio reception Correct answer.
  4. To measure the aircraft's static pressure for the altimeter

Explanation

Static dischargers bleed off the static charge that builds up as the aircraft moves through the air, which would otherwise cause radio interference. They are not intended to conduct lightning strikes, which involve much larger currents. They do not affect flutter or measure pressure.

Question 45Aircraft general knowledge (airframe, systems and powerplants)

A pilot is planning a flight and the outside air temperature at the cruising level is well below standard. How does this affect the engine's ability to produce power compared with a standard day?

  1. Power output decreases because the fuel vaporises less readily
  2. Power output is unchanged because temperature does not affect density
  3. Power output decreases because cold air is less dense
  4. Power output increases because the denser air provides more oxygen for combustion Correct answer.

Explanation

Colder air is denser, so each intake stroke draws in a greater mass of air and therefore more oxygen. This allows more fuel to be burned and increases power output, although it may require leaning. Colder air does not reduce density or prevent vaporisation.

Question 46Aircraft general knowledge (airframe, systems and powerplants)

In a gas turbine engine, what is the function of the exhaust nozzle?

  1. To mix fuel with the exhaust for afterburning in all engines
  2. To drive the compressor through a mechanical linkage
  3. To accelerate the exhaust gases and produce thrust Correct answer.
  4. To cool the exhaust gases before they leave the engine

Explanation

The exhaust nozzle expands and accelerates the hot gases leaving the turbine, converting remaining pressure into velocity and producing thrust. It does not cool the gases or drive the compressor mechanically. Afterburning is fitted only to some engines.

Question 47Aircraft general knowledge (airframe, systems and powerplants)

An aircraft is fitted with a constant-speed propeller and the pilot selects a higher RPM in cruise without changing throttle. What is the immediate effect on manifold pressure?

  1. Manifold pressure decreases because the engine turns faster and consumes more air Correct answer.
  2. Manifold pressure decreases only if the mixture is leaned
  3. Manifold pressure is unaffected by propeller RPM
  4. Manifold pressure increases because the propeller load decreases

Explanation

Selecting a higher RPM increases engine speed, so the engine pumps more air through the intake. With the throttle unchanged the manifold pressure falls slightly because the throttle is a smaller restriction relative to the increased airflow. This is why RPM is set before manifold pressure in cruise.

Question 48Aircraft general knowledge (airframe, systems and powerplants)

A multi-engine aircraft has one engine fail in flight. Which statement best explains why the operating engine may be limited to a lower power setting than its maximum continuous rating?

  1. The fuel system automatically reduces flow to the operating engine
  2. The failed engine's propeller windmills and drives the operating engine
  3. The remaining engine must provide asymmetric thrust and the airframe is limited by the resulting yaw and control authority Correct answer.
  4. The operating engine's cooling is improved by the failure of the other engine

Explanation

With one engine failed, the operating engine produces asymmetric thrust that must be balanced by rudder. Control authority and structural limits mean the engine may be restricted to a lower setting than its maximum continuous rating. The failed engine's windmilling propeller adds drag but does not drive the operating engine.

Question 49Aircraft general knowledge (airframe, systems and powerplants)

During a descent a pilot closes the throttle and the engine begins to run roughly, then recovers when the throttle is opened. Which explanation is most consistent with these symptoms?

  1. The propeller governor has overspeeded the engine
  2. The mixture has become excessively lean at the closed throttle setting because the idle circuit is not adjusted correctly Correct answer.
  3. The magnetos have failed and only one is operating
  4. The fuel tanks have run dry

Explanation

At closed throttle the engine runs on the idle circuit, and if that circuit is incorrectly adjusted the mixture becomes excessively lean, causing rough running. Opening the throttle restores flow through the main metering system and the engine recovers. This pattern points to idle mixture adjustment rather than ignition or fuel exhaustion.

Question 50Aircraft general knowledge (airframe, systems and powerplants)

A pilot notices that the cylinder head temperature is rising abnormally during a climb at high power and low airspeed. Which combination of actions best addresses the cause?

  1. Lean the mixture and reduce airspeed to reduce drag
  2. Reduce oil pressure and increase manifold pressure
  3. Enrich the mixture and increase airspeed to improve cooling Correct answer.
  4. Increase RPM and close the cowl flaps

Explanation

High cylinder head temperature at high power and low airspeed results from high heat release combined with reduced cooling airflow. Enriching the mixture lowers combustion temperature and increasing airspeed improves cooling, so both address the cause. Leaning or reducing airspeed would worsen the condition.