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PPL Aircraft General Knowledge practice questions

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Question 1Airframe, systems and powerplant

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

  1. It controls the pitch of the propeller blades directly by mechanical linkage
  2. It synchronises engine RPM with the electrical generator frequency
  3. It meters fuel flow to match the selected power setting
  4. It regulates oil pressure to the propeller hub to hold the selected RPM Correct answer.

Explanation

The governor senses engine RPM and varies the oil pressure supplied to the propeller hub, which drives the blade angle and therefore keeps RPM at the value selected by the pilot. It does not meter fuel, mechanically move the blades itself, or tie RPM to generator frequency.

Question 2Airframe, systems and powerplant

Which component converts the reciprocating motion of the piston into rotary motion of the crankshaft?

  1. The magneto
  2. The camshaft
  3. The valve lifter
  4. The connecting rod Correct answer.

Explanation

The connecting rod links the piston to the crankshaft journal and swings through an arc as the piston reciprocates, thereby turning the crankshaft. The camshaft operates the valves, the lifter transfers cam motion to the pushrod, and the magneto produces ignition voltage.

Question 3Airframe, systems and powerplant

In a four-stroke reciprocating engine, what occurs during the compression stroke?

  1. The exhaust valve is open and the piston moves toward the crankshaft
  2. Both valves are open and the piston passes top dead centre
  3. The intake valve is open and the piston moves toward the crankshaft
  4. Both valves are closed and the piston moves toward the cylinder head Correct answer.

Explanation

Compression begins after the intake valve closes, with both valves seated, and the rising piston reduces the trapped mixture volume. The intake stroke is the one with the intake valve open and piston descending, while the exhaust stroke has the exhaust valve open.

Question 4Airframe, systems and powerplant

What is the purpose of the magneto in a piston engine ignition system?

  1. It advances ignition timing automatically with altitude
  2. It provides the current for the engine starter motor
  3. It steps up battery voltage to fire the spark plugs
  4. It generates its own high-tension voltage independently of the aircraft battery Correct answer.

Explanation

A magneto is a self-contained generator driven by the engine that produces its own electrical energy and steps it up to fire the plugs, so ignition continues even if the aircraft electrical system fails. It does not rely on battery voltage, and it does not supply the starter motor.

Question 5Airframe, systems and powerplant

Why do most light aircraft have two independent magnetos?

  1. To provide redundancy and improve combustion through dual ignition Correct answer.
  2. To double the spark intensity at high altitude
  3. To reduce the weight of the ignition harness
  4. To allow one magneto to drive the starter and the other the plugs

Explanation

Dual magnetos give a backup in case one fails and fire two plugs per cylinder, which improves combustion and gives a small power gain. The arrangement does not increase spark intensity, drive the starter, or reduce harness weight.

Question 6Airframe, systems and powerplant

What is the function of the voltage regulator in a light aircraft charging system?

  1. It regulates the current drawn by the avionics bus
  2. It limits alternator or generator output voltage to a safe value Correct answer.
  3. It converts alternating current to direct current
  4. It protects the battery from over-discharge on the ground

Explanation

The voltage regulator controls the field current so that the generator or alternator output stays within a safe voltage band, protecting the battery and equipment. Rectification is done by diodes, and the regulator does not manage avionics load or prevent ground discharge.

Question 7Airframe, systems and powerplant

What does the term 'dihedral' describe on an aircraft wing?

  1. The taper of the wing from root to tip
  2. The upward angle of the wings relative to the lateral axis Correct answer.
  3. The rearward sweep of the leading edge
  4. The angle between the wing chord and the fuselage centreline

Explanation

Dihedral is the upward angle of the wing panels measured from the lateral axis, and it contributes to roll stability. Angle to the fuselage centreline is the angle of incidence, rearward sweep is sweepback, and root-to-tip reduction is taper.

Question 8Airframe, systems and powerplant

Which structural member carries the main bending loads along the span of a wing?

  1. The rib
  2. The leading edge skin
  3. The aileron
  4. The spar Correct answer.

Explanation

The spar runs spanwise and is the principal bending member of the wing, with the skin and stringers contributing to shear and torsion. Ribs give the wing its aerofoil shape, the leading edge skin is non-structural covering, and the aileron is a control surface.

Question 9Airframe, systems and powerplant

What is the purpose of an oil cooler bypass valve in a piston engine lubrication system?

  1. It filters metal particles from the oil before it reaches the cooler
  2. It increases oil pressure when the engine is at high RPM
  3. It vents crankcase pressure to the atmosphere
  4. It prevents oil from entering the cooler when the oil is too cold to flow properly Correct answer.

Explanation

When oil is cold and viscous, the bypass valve routes it around the cooler so that it can circulate and warm up, avoiding excessive pressure and starvation. Filtration is done by the oil filter or screen, and crankcase venting is a separate function.

Question 10Airframe, systems and powerplant

During a run-up, the pilot selects each magneto in turn. What does a large RPM drop on one magneto indicate?

  1. That the selected magneto or its associated plugs are faulty Correct answer.
  2. That the engine is running too rich at idle
  3. That the propeller governor is out of adjustment
  4. That the fuel pump is delivering insufficient pressure

Explanation

Selecting one magneto means that magneto alone fires its plugs; an excessive drop points to a weak magneto, a fouled plug, or a fault in that circuit. Mixture, propeller governor, and fuel pressure do not produce a magneto-specific drop.

Question 11Airframe, systems and powerplant

A pilot notices the ammeter shows a discharge in cruise flight after a period of normal charging. Which interpretation is most appropriate?

  1. The voltage regulator is overcharging the battery
  2. The alternator or generator may have failed and the battery is supplying the electrical load Correct answer.
  3. The starter relay has remained engaged
  4. The battery is being charged normally and no action is needed

Explanation

A sustained discharge indicates the generating source is no longer supplying current, so the battery is carrying the load and will eventually run down. Normal charging shows a positive indication, overcharging would show excessive charge, and a stuck starter relay would show a large discharge on the ground mainly.

Question 12Airframe, systems and powerplant

What is the primary consequence of an excessively lean mixture at high power settings?

  1. Excessive oil consumption from cylinder washdown
  2. Detonation and possible damage from high cylinder head temperatures Correct answer.
  3. Fouled spark plugs from unburned fuel
  4. A rich cut at low altitude

Explanation

A lean mixture at high power raises combustion temperatures and pressures, which can lead to detonation and overheating of the cylinders. Fouling and cylinder washdown are associated with an overly rich mixture, and a rich cut is not a lean-mixture phenomenon.

Question 13Airframe, systems and powerplant

Why is carburettor icing a greater risk when the outside air temperature is between about -10°C and +10°C with high humidity?

  1. The throttle valve freezes because it is electrically heated
  2. The air filter becomes blocked with ice at these temperatures
  3. The fuel is more volatile at these temperatures
  4. The venturi pressure drop and fuel vaporisation cool the mixture below freezing Correct answer.

Explanation

In the venturi, the pressure drop and the latent heat absorbed by vaporising fuel can cool the mixture by roughly 20°C or more, dropping it below 0°C even in mild ambient conditions. Humidity supplies the moisture that freezes on the throttle and venturi surfaces.

Question 14Airframe, systems and powerplant

What is the function of the mixture control in a float-type carburettor fuel system?

  1. It adjusts the fuel flow to maintain the correct fuel-to-air ratio as altitude changes Correct answer.
  2. It controls the fuel pressure delivered by the engine-driven pump
  3. It sets the idle RPM of the engine
  4. It adjusts the ignition timing for the selected power

Explanation

As altitude increases, air density falls, and the mixture control reduces fuel flow to keep the fuel-to-air ratio appropriate. Idle RPM is set by the throttle stop, fuel pressure is regulated by the pump and pressure relief, and ignition timing is fixed by the magneto.

Question 15Airframe, systems and powerplant

In a constant-speed propeller system, what happens when the pilot moves the propeller control toward high RPM?

  1. The governor increases oil pressure to the hub, coarsening the blade angle
  2. The propeller blades move to the feathered position
  3. The engine RPM is limited by the wastegate
  4. The governor reduces oil pressure, allowing the blades to move toward fine pitch Correct answer.

Explanation

For most light aircraft installations, selecting a higher RPM causes the governor to reduce oil pressure to the hub so that the blades move to a finer pitch. Fine pitch reduces blade load and allows higher RPM. Feathering is a separate selection, and the wastegate controls turbocharger boost.

Question 16Airframe, systems and powerplant

What is the purpose of a turbocharger's wastegate?

  1. It meters fuel to match the increased manifold pressure
  2. It drives the propeller governor at high altitude
  3. It regulates exhaust gas flow to the turbine to control boost pressure Correct answer.
  4. It cools the compressed air before it reaches the throttle body

Explanation

The wastegate bypasses exhaust gas around the turbine, so opening or closing it controls the turbine speed and therefore the boost delivered by the compressor. Intercooling handles charge cooling, fuel metering is the fuel servo's job, and the governor is independent of the turbocharger.

Question 17Airframe, systems and powerplant

What is the function of the hydraulic system's pressure relief valve?

  1. It maintains a constant flow to the actuators regardless of demand
  2. It filters contaminants from the hydraulic fluid
  3. It stores pressure energy for emergency gear extension
  4. It limits system pressure by returning excess fluid to the reservoir Correct answer.

Explanation

The relief valve opens when pressure exceeds a set value, bypassing or returning fluid to the reservoir so that hoses and components are protected. Flow control is handled by selector and priority valves, filtration by filters, and energy storage by the accumulator.

Question 18Airframe, systems and powerplant

A pilot observes that the manifold pressure gauge reads near ambient with the engine stopped, and the reading rises slightly when the throttle is opened on the ground. What does the gauge measure?

  1. Cabin differential pressure
  2. Pressure difference across the air filter
  3. Absolute pressure in the induction manifold Correct answer.
  4. Fuel pressure at the carburettor inlet

Explanation

The manifold pressure gauge displays absolute pressure in the induction system, referenced to a vacuum, so it reads approximately ambient when the engine is stopped. Fuel pressure and cabin differential are shown on separate gauges.

Question 19Airframe, systems and powerplant

During a preflight inspection, a pilot finds a small amount of fuel staining at a wing skin joint but no visible crack. Which action is correct?

  1. Ignore it because a small stain is normal for integral tanks
  2. Have the area inspected by maintenance before flight Correct answer.
  3. Drain the tank completely and refuel to the tabs
  4. Wipe the stain and depart, monitoring fuel quantity in flight

Explanation

Fuel staining at a joint may indicate a seeping integral tank or a developing leak that could worsen, so it must be assessed by maintenance before flight. Wiping and departing, ignoring it, or simply refuelling does not address the possible structural or sealing defect.

Question 20Airframe, systems and powerplant

Why is the engine oil changed at specified intervals rather than only when the level is low?

  1. The oil filter cannot be replaced without draining the sump
  2. Oil viscosity increases permanently with use and must be replaced
  3. Oil accumulates contaminants and its additive package depletes over time Correct answer.
  4. Oil quantity decreases only through leaks, so intervals are arbitrary

Explanation

In service, oil collects combustion by-products, metal particles, and moisture, and its anti-wear and dispersant additives are consumed, so scheduled changes maintain protection. Viscosity does not simply rise permanently, and the filter can be changed separately.

Question 21Airframe, systems and powerplant

What is the purpose of the vacuum system in a light aircraft equipped with gyroscopic instruments?

  1. It supplies air for cabin pressurisation
  2. It drives the gyros of the attitude and heading indicators Correct answer.
  3. It operates the landing gear retraction mechanism
  4. It provides pressure for the altimeter and airspeed indicator

Explanation

Engine-driven vacuum pumps supply suction that spins the gyros in vacuum-driven attitude and heading indicators. The altimeter and airspeed indicator are pitot-static instruments, gear retraction is hydraulic or electric, and cabin pressurisation uses bleed air.

Question 22Airframe, systems and powerplant

An engine with a fixed-pitch propeller is operating at full throttle at sea level. As the aircraft climbs, what happens to manifold pressure and engine power if the throttle is not adjusted?

  1. Manifold pressure decreases and power decreases Correct answer.
  2. Manifold pressure increases and power increases
  3. Manifold pressure decreases but power increases
  4. Manifold pressure stays constant and power stays constant

Explanation

As altitude increases, ambient pressure falls, so the absolute pressure in the induction manifold falls and the engine produces less power at a fixed throttle setting. This is why normally aspirated engines require leaning and why turbocharging is used for altitude performance.

Question 23Airframe, systems and powerplant

A normally aspirated engine with a constant-speed propeller is leaned in cruise. Which combination best explains why the pilot monitors cylinder head temperature and exhaust gas temperature together?

  1. EGT indicates oil temperature while CHT indicates fuel flow
  2. CHT peaks at best-power mixture while EGT stays constant across the mixture range
  3. EGT peaks near best-power mixture, while CHT reflects the heat load on the cylinder and rises toward the lean side Correct answer.
  4. Both gauges measure the same quantity and are provided for redundancy

Explanation

Exhaust gas temperature peaks near the best-power mixture and falls on either side, so it is used to locate a target mixture. Cylinder head temperature responds to the overall heat rejected to the cylinder and tends to rise as the mixture is leaned past peak, making it the limiting indication for engine protection.

Question 24Airframe, systems and powerplant

An aircraft has a 28-volt electrical system and the ammeter shows a high charge rate immediately after engine start that slowly decreases. Which explanation is most accurate?

  1. The battery is recharging after the energy used for starting, and the regulator reduces the charge rate as it reaches full charge Correct answer.
  2. The alternator is undersized and cannot supply the bus
  3. The voltage regulator has failed and is overcharging the battery
  4. The starter relay is stuck closed and drawing current

Explanation

After start, the battery accepts a high charge current because it has been partly discharged, and the regulator tapers the rate as terminal voltage rises. A failed regulator would overcharge persistently, an undersized alternator would show a discharge with load, and a stuck starter relay would show a large continuous drain.

Question 25Airframe, systems and powerplant

In a fuel-injected engine, what is the function of the fuel manifold valve (spider)?

  1. It distributes metered fuel equally to the individual cylinder injector lines Correct answer.
  2. It returns unused fuel to the tank
  3. It regulates the fuel pressure delivered by the engine-driven pump
  4. It controls the mixture by bleeding air into the fuel lines

Explanation

The manifold valve receives metered fuel from the fuel control unit and divides it among the lines to the individual cylinder injectors. Pressure regulation is done by the fuel pump relief valve, mixture is set in the fuel control unit, and continuous-flow systems do not return unused fuel from the spider.

Question 26Airframe, systems and powerplant

In a light aircraft's piston engine, what is the function of the exhaust valve?

  1. It seals the combustion chamber during compression and opens to release burnt gases after the power stroke Correct answer.
  2. It provides a pressure seal between the cylinder barrel and the crankcase
  3. It admits the fuel-air charge into the cylinder during the intake stroke
  4. It regulates the flow of cooling air around the cylinder fins

Explanation

The exhaust valve is held closed by its spring during intake, compression and power, sealing the combustion chamber. It is opened by the camshaft at the end of the power stroke so burnt gases can be expelled during the exhaust stroke.

Question 27Airframe, systems and powerplant

What does the 'angle of attack' of a propeller blade refer to?

  1. The angle through which the blade twists from root to tip
  2. The angle between the blade's chord line and the propeller axis of rotation
  3. The angle between the blade's chord line and the relative airflow Correct answer.
  4. The angle between the direction of rotation and the aircraft's longitudinal axis

Explanation

Blade angle of attack is measured between the blade chord line and the relative airflow, which is the vector sum of rotational speed and forward speed. It changes with airspeed and RPM even when the blade is fixed in the hub.

Question 28Airframe, systems and powerplant

Which statement correctly describes the purpose of the fuel strainer or gascolator in a light aircraft fuel system?

  1. It shuts off fuel supply when the engine stops
  2. It traps water and coarse particles before fuel reaches the carburettor or engine-driven pump Correct answer.
  3. It measures the rate of fuel flow to the engine for the fuel flow gauge
  4. It maintains a constant fuel pressure at the carburettor inlet

Explanation

The gascolator is normally the lowest point in the fuel system, where water and sediment collect and can be drained during preflight. It protects downstream components and the engine from contamination.

Question 29Airframe, systems and powerplant

A pilot notices the cylinder head temperature rising steadily in a climb while oil temperature remains normal. Which interpretation is most appropriate?

  1. The oil cooler is blocked and the oil system must be inspected before further flight
  2. Cooling airflow over the cylinder fins is inadequate and the climb attitude or airspeed should be adjusted Correct answer.
  3. The mixture is too rich and should be leaned to reduce combustion temperature
  4. The engine is being over-cooled and the cowl flaps should be closed further

Explanation

Cylinder head temperature responds mainly to airflow through the cylinder fins and to power setting. A high CHT with normal oil temperature in a climb usually means the cooling airflow is insufficient, so lowering the nose or reducing power restores the margin.

Question 30Airframe, systems and powerplant

Why does an aircraft battery compartment normally have a vent or drain arrangement?

  1. To equalise pressure between the battery cells and the cabin
  2. To allow the battery to be removed without disconnecting the cables
  3. To keep the battery warm in cold weather
  4. To carry away gases and electrolyte that may escape from the battery Correct answer.

Explanation

Lead-acid batteries can vent hydrogen and can spill electrolyte if they are overcharged or damaged. Venting and a drain prevent corrosive fluid and flammable gas from accumulating in the structure.

Question 31Airframe, systems and powerplant

An aircraft has a fixed-pitch propeller and the pilot applies carburettor heat in cruise. What immediate change in engine indications should be expected?

  1. RPM falls slightly and manifold pressure may rise a little because warmer, less dense air enters the engine Correct answer.
  2. Manifold pressure rises and RPM increases slightly
  3. Both RPM and manifold pressure fall sharply and remain low
  4. Oil pressure falls as the heated air thins the oil

Explanation

Carburettor heat routes air through a heat exchanger, so the charge becomes warmer and less dense. With a fixed-pitch propeller the engine typically loses a little RPM, and the throttle plate position means manifold pressure may read slightly higher.

Question 32Airframe, systems and powerplant

What is the primary function of the propeller governor in a constant-speed system?

  1. It limits maximum engine RPM by throttling the fuel supply
  2. It converts engine torque into thrust by changing blade shape
  3. It synchronises the RPM of twin engines automatically
  4. It meters engine oil pressure to the propeller hub to hold the selected RPM Correct answer.

Explanation

The governor senses engine RPM and directs oil to or from the propeller hub, changing blade angle to keep RPM at the value selected with the cockpit control. It acts as a closed-loop speed controller.

Question 33Airframe, systems and powerplant

During a magneto check the engine continues to run when the ignition switch is placed in the OFF position. Which conclusion is most defensible?

  1. The engine is running on the auxiliary magneto only and the check may continue
  2. The spark plugs are fouled and the engine will stop once they clear
  3. The ignition switch is faulty only in the START position
  4. The magneto ground circuit is open and the engine may keep running, so the aircraft should not be flown until rectified Correct answer.

Explanation

Magnetos generate their own current and are stopped only when the P-lead grounds them. If the engine runs with the switch OFF, the ground path is broken and the propeller remains live, presenting a serious hazard that must be fixed before flight.

Question 34Airframe, systems and powerplant

An aircraft with a 24-volt system shows the ammeter reading near zero in cruise with all equipment on, and the battery is found flat after several flights. Which explanation best fits these observations?

  1. The voltage regulator is allowing an excessive charge rate that boils the battery
  2. The starter relay is stuck closed and drains the battery in flight
  3. The alternator is not producing enough output to carry the electrical load, so the battery supplies the deficit Correct answer.
  4. The ammeter is reading correctly and the battery is simply old

Explanation

A near-zero ammeter with all loads on can mean the charging source is only just balancing demand, or is failing to supply it, so the battery quietly discharges. A flat battery after repeated flights supports an inadequate charging output rather than a normal indication.

Question 35Mass and balance

In mass and balance terminology, what does the abbreviation MTOM represent?

  1. Mean Take-Off Moment
  2. Maximum Take-Off Mass Correct answer.
  3. Minimum Transport Operating Mass
  4. Maximum Taxi Operating Mass

Explanation

MTOM stands for Maximum Take-Off Mass, the maximum mass at which the aircraft is certified to begin the take-off run. It is a structural and certification limit that must never be exceeded, and it includes the aircraft, fuel, crew, payload and baggage.

Question 36Mass and balance

Which mass is defined as the aircraft mass with all operating items aboard but excluding usable fuel and traffic load?

  1. Zero Fuel Mass
  2. Basic Empty Mass
  3. Landing Mass
  4. Dry Operating Mass Correct answer.

Explanation

Dry Operating Mass is the basic empty mass plus crew, crew baggage, catering, potable water and other operational items, but excluding usable fuel and traffic load. It is the starting point from which fuel and payload are added to determine the take-off mass.

Question 37Mass and balance

Which of the following items is classified as traffic load rather than part of the dry operating mass?

  1. Crew baggage
  2. Potable water
  3. Catering supplies
  4. Passengers and cargo Correct answer.

Explanation

Traffic load consists of passengers, baggage, cargo and mail that generate revenue, and it is added to the dry operating mass to obtain the zero fuel mass. Crew baggage, catering and potable water are operational items already contained in the dry operating mass.

Question 38Mass and balance

An aircraft has a dry operating mass of 40 000 kg, a take-off fuel of 8 000 kg and a traffic load of 12 000 kg. What is the take-off mass?

  1. 48 000 kg
  2. 52 000 kg
  3. 60 000 kg Correct answer.
  4. 40 000 kg

Explanation

Take-off mass equals dry operating mass plus take-off fuel plus traffic load: 40 000 + 8 000 + 12 000 = 60 000 kg. All three components must be summed, since the dry operating mass alone excludes both fuel and payload.

Question 39Mass and balance

What is the definition of the centre of gravity of an aircraft?

  1. The point on the wing where lift is assumed to be concentrated
  2. The location of the main landing gear axle
  3. The geometric midpoint of the fuselage between nose and tail
  4. The point at which the total weight of the aircraft is considered to act Correct answer.

Explanation

The centre of gravity is the point through which the total weight of the aircraft acts, and it is the balance point of the whole mass. Its position determines the moment arm of weight about the datum and therefore affects stability and control.

Question 40Mass and balance

In mass and balance calculations, what is a moment?

  1. The time taken for the aircraft to rotate on take-off
  2. A mass multiplied by its distance from the datum Correct answer.
  3. A force divided by the wing area
  4. The total mass of the aircraft divided by its length

Explanation

A moment is the product of a mass and its arm, the distance measured from the reference datum. Moments are summed and divided by total mass to find the centre of gravity position.

Question 41Mass and balance

Where is the datum located on most aircraft used for mass and balance purposes?

  1. At the nose of the aircraft in every case
  2. At the trailing edge of the wing root
  3. At a specified reference point defined in the aircraft documentation Correct answer.
  4. At the main landing gear

Explanation

The datum is an arbitrary but specified reference point chosen by the manufacturer and stated in the aircraft documentation. All arms are measured from it, so it may lie ahead of, behind or within the aircraft.

Question 42Mass and balance

What does the abbreviation MAC mean in aircraft mass and balance?

  1. Mean Aerodynamic Chord Correct answer.
  2. Maximum Allowable Cargo
  3. Mean Aerodynamic Centre
  4. Minimum Aft Centre

Explanation

MAC stands for Mean Aerodynamic Chord, the average chord of the wing and the reference against which the longitudinal centre of gravity is often expressed as a percentage. This allows a common measure of CG position across different aircraft types.

Question 43Mass and balance

An item of mass 150 kg is loaded 12 m aft of the datum. What is its moment about the datum?

  1. 12.5 kg·m
  2. 162 kg·m
  3. 1 800 kg·m Correct answer.
  4. 0.08 kg·m

Explanation

The moment is the mass multiplied by its arm: 150 kg × 12 m = 1 800 kg·m. The result is positive because the arm is measured aft of the datum.

Question 44Mass and balance

An aircraft has a total mass of 2 500 kg and a total moment of 21 250 kg·m about the datum. Where is the centre of gravity?

  1. 8.5 m aft of the datum Correct answer.
  2. 23 750 m aft of the datum
  3. 0.118 m aft of the datum
  4. 21 250 m aft of the datum

Explanation

The CG position is found by dividing the total moment by the total mass: 21 250 ÷ 2 500 = 8.5 m aft of the datum. The result is expressed as a distance from the datum, not as a moment.

Question 45Mass and balance

Why must the centre of gravity be kept within the forward limit?

  1. To increase the cruise speed of the aircraft
  2. To ensure sufficient elevator authority for rotation and to avoid excessive nose-down tendency Correct answer.
  3. To reduce the structural weight of the wing
  4. To lower the fuel consumption at high altitude

Explanation

A CG too far forward creates a large nose-down moment that requires more elevator force to counter, reducing the authority available for rotation and flare. Keeping the CG aft of the forward limit ensures adequate control and prevents excessive stick forces.

Question 46Mass and balance

What is the principal hazard of operating with the centre of gravity behind the aft limit?

  1. Increased take-off distance
  2. Higher engine oil consumption
  3. Shorter landing roll
  4. Reduced longitudinal stability and possible loss of control Correct answer.

Explanation

An aft centre of gravity reduces the static margin between the CG and the aerodynamic centre, decreasing longitudinal stability. The aircraft may become unstable in pitch, and recovery from a stall or upset can become difficult or impossible.

Question 47Mass and balance

An aircraft has a basic empty mass of 1 000 kg at an arm of 2.0 m and a pilot of 80 kg at an arm of 1.5 m. What is the CG position?

  1. 1.75 m
  2. 1.90 m
  3. 2.04 m
  4. 1.96 m Correct answer.

Explanation

Total moment = 1 000 × 2.0 + 80 × 1.5 = 2 000 + 120 = 2 120 kg·m, and total mass = 1 080 kg. Dividing gives 2 120 ÷ 1 080 = 1.96 m from the datum.

Question 48Mass and balance

An aircraft has a maximum zero fuel mass of 50 000 kg. With a dry operating mass of 38 000 kg, what is the maximum traffic load that can be carried?

  1. 88 000 kg
  2. 12 000 kg Correct answer.
  3. 38 000 kg
  4. 50 000 kg

Explanation

Maximum traffic load is the maximum zero fuel mass minus the dry operating mass: 50 000 − 38 000 = 12 000 kg. This payload also has to be checked against the take-off and landing mass limits with the fuel required.

Question 49Mass and balance

What does a negative arm in a mass and balance calculation indicate?

  1. The moment of the item is zero
  2. The item is located forward of the datum Correct answer.
  3. The item is loaded above the floor line
  4. The item has no mass

Explanation

Arms are measured from the datum, and a negative sign means the item lies forward of that reference point. The resulting moment is also negative and must be subtracted when the total moment is summed.

Question 50Mass and balance

Which of the following correctly expresses the relationship between zero fuel mass and take-off mass?

  1. Take-off mass equals zero fuel mass plus take-off fuel Correct answer.
  2. Zero fuel mass equals take-off mass plus trip fuel
  3. Take-off mass equals zero fuel mass minus fuel
  4. Zero fuel mass equals take-off mass plus reserve fuel

Explanation

Take-off mass is the zero fuel mass plus the take-off fuel, since the zero fuel mass already contains the dry operating mass and traffic load but no usable fuel. Adding the fuel aboard at brake release gives the take-off mass.