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NZ CAA PPL Aircraft Technical study materials
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NZ CAA PPL Aircraft Technical practice questions

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Question 1Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a four-stroke aircraft reciprocating engine, during which stroke does the piston move upward with both valves closed, compressing the fuel-air mixture?

  1. Exhaust stroke
  2. Compression stroke Correct answer.
  3. Induction stroke
  4. Power stroke

Explanation

The compression stroke begins with the piston at the bottom of its travel and both valves seated, so the trapped mixture is squeezed into a smaller volume as the piston rises. This raises pressure and temperature before ignition, which occurs near the top of the stroke. The other three strokes each involve at least one valve being open.

Question 2Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The purpose of the magneto in a light aircraft ignition system is to:

  1. Advance and retard ignition timing automatically as altitude changes
  2. Convert low-voltage battery current into high-voltage pulses for the spark plugs
  3. Provide a self-contained source of high-tension current without relying on the aircraft battery Correct answer.
  4. Supply low-voltage current to the starter motor during engine cranking

Explanation

A magneto is a self-exciting generator: a rotating magnet induces current in a primary coil, and the opening of the primary circuit induces a high voltage in the secondary winding that fires the plug. Because it generates its own electricity, the engine keeps running even if the aircraft electrical system fails. Two magnetos are normally fitted so each cylinder has a dual ignition source.

Question 3Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

During a magneto check before takeoff, selecting the LEFT magneto position causes the engine to run rough and the RPM drop is excessive. What is the most likely interpretation?

  1. The engine primer is unlocked and enriching the mixture
  2. The right magneto is faulty and the engine is running on the left magneto alone
  3. Both magnetos are operating normally but the mixture is too rich
  4. The left magneto is faulty or its plug lead is grounding, so the engine is running on the right magneto alone Correct answer.

Explanation

Selecting LEFT grounds the right magneto, so the engine runs only on the left magneto. An excessive drop or rough running therefore points to a fault in the left magneto circuit or its associated spark plugs. A normal drop is small and smooth, typically under about 150 RPM with a difference between the two of no more than about 50 RPM.

Question 4Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A fixed-pitch propeller is described as having a pitch of 60 inches. This means the propeller would:

  1. Advance 60 inches through the air in one revolution if there were no slip Correct answer.
  2. Have a blade length of 60 inches from hub centre to tip
  3. Produce 60 inches of manifold pressure at full throttle
  4. Turn at 60 revolutions per second at cruise power

Explanation

Geometric pitch is the theoretical forward distance a propeller would travel in one revolution if it screwed through the air like a bolt through a solid medium. In practice the aircraft moves less than this because air is not rigid, and the difference is called slip. Pitch is a geometric property and is unrelated to blade length or engine power.

Question 5Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A constant-speed propeller unit uses a governor to maintain a selected RPM. If the aircraft accelerates in a descent with the throttle unchanged, the governor will:

  1. Increase blade angle to absorb the extra power and hold RPM constant Correct answer.
  2. Decrease blade angle to prevent an overspeed
  3. Allow RPM to rise because the governor only acts at low power
  4. Feather the blades to limit drag

Explanation

In a descent the propeller tends to speed up as the aircraft accelerates and the blade angle of attack falls. The governor senses the RPM rise and directs oil to increase blade angle, which increases the load on the engine and restores the selected RPM. This keeps RPM constant while manifold pressure falls, so the pilot must manage power to avoid exceeding limits.

Question 6Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The function of the carburettor heat control in a float-type carburettor installation is to:

  1. Direct heated air into the induction system to melt or prevent ice in the carburettor Correct answer.
  2. Warm the fuel before it reaches the float chamber to improve vaporisation
  3. Raise the temperature of the cabin air supply
  4. Heat the engine oil during cold starts

Explanation

Carburettor heat takes air from around an exhaust-heated muff and ducts it into the carburettor intake. This raises the temperature in the venturi and throttle area, melting existing ice and preventing further formation. Because heated air is less dense, applying carburettor heat normally causes a small RPM drop.

Question 7Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

Carburettor ice is most likely to form when the outside air temperature is:

  1. Well below freezing, around -20 degrees Celsius
  2. Between roughly -7 and +21 degrees Celsius with high humidity Correct answer.
  3. Above 30 degrees Celsius with low humidity
  4. Below -30 degrees Celsius in clear dry air

Explanation

Vaporisation of fuel and the pressure drop in the venturi cool the mixture substantially, so ice can form at outside temperatures well above freezing. The classic danger zone is roughly -7 to +21 degrees Celsius when relative humidity is high. Very cold, dry air is less favourable because there is little moisture to freeze.

Question 8Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a fuel-injected light aircraft engine, the mixture control is used primarily to:

  1. Select between the main and auxiliary fuel tanks
  2. Adjust the ratio of fuel to air reaching the cylinders as altitude changes Correct answer.
  3. Set the idle speed of the engine on the ground
  4. Control the amount of boost produced by the turbocharger

Explanation

As altitude increases, air density falls and the fuel-air mixture becomes richer unless fuel flow is reduced. The mixture control leans the mixture by reducing fuel flow, restoring the correct ratio for efficient combustion. It is also used to enrich for high power and to cut off fuel at shutdown.

Question 9Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

An aircraft engine oil system that uses a dry-sump arrangement is characterised by:

  1. Oil stored in a separate tank and pumped to and from the engine by pressure and scavenge pumps Correct answer.
  2. Oil that is cooled only by the airstream on the sump
  3. Oil that is used once and then discharged overboard
  4. Oil stored in the sump beneath the crankshaft and circulated by splash

Explanation

In a dry-sump system oil is carried in a separate tank, a pressure pump feeds it to the engine, and scavenge pumps return it to the tank. This allows a larger oil supply and better cooling, and it is common on aerobatic and higher-power engines. A wet-sump engine keeps its oil in the sump and uses a single pressure pump.

Question 10Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The primary purpose of the oil cooler in a light aircraft engine installation is to:

  1. Provide a reserve of oil for the propeller governor
  2. Warm the oil during cold starts
  3. Remove heat from the oil so it stays within its operating viscosity range Correct answer.
  4. Filter metal particles from the oil

Explanation

Oil absorbs heat from bearings and other components, and its temperature must be kept within limits so viscosity remains adequate. The oil cooler, usually an air-to-oil radiator, dissipates that heat to the airstream. A viscosity that is too low reduces the oil film's load-carrying ability.

Question 11Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The cylinder head temperature gauge in an air-cooled engine is most useful because it indicates:

  1. Whether the cylinders are being overheated by a lean mixture or inadequate cooling Correct answer.
  2. The temperature of the exhaust gas leaving the cylinder
  3. The temperature of the oil leaving the cooler
  4. The temperature of the outside air entering the cowling

Explanation

Cylinder head temperature responds to combustion heat and cooling airflow, so it warns of overheating from a lean mixture, high power, or blocked cooling. It is a key limit during climb and lean-of-peak operation. Oil temperature and exhaust gas temperature are separate indications.

Question 12Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a simple pitot-static system, the airspeed indicator uses:

  1. The difference between two static ports on opposite sides of the fuselage
  2. Pitot pressure only, compared with a sealed reference
  3. The difference between pitot (dynamic) pressure and static pressure Correct answer.
  4. Static pressure only, compared with a sealed reference

Explanation

The airspeed indicator is a differential pressure instrument: pitot pressure enters one side of the capsule and static pressure the other. The difference, dynamic pressure, is proportional to the square of the true airspeed and is displayed as indicated airspeed. Blocked or leaking pitot or static sources therefore cause characteristic errors.

Question 13Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

If the static source becomes blocked during a climb, the airspeed indicator will:

  1. Read correctly because only pitot pressure matters
  2. Read lower than actual airspeed because the trapped static pressure is higher than ambient Correct answer.
  3. Read higher than actual airspeed because the trapped static pressure is lower than ambient
  4. Read zero until the blockage clears

Explanation

With the static port blocked, the static pressure trapped in the instrument case stays at the value from the altitude where the blockage occurred. In a climb, ambient pressure falls below that trapped value, so the differential across the capsule is smaller than it should be and the instrument under-reads. The altimeter would also freeze at the blocked altitude.

Question 14Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The altimeter in an aircraft is essentially:

  1. A differential pressure gauge comparing pitot and static pressure
  2. An aneroid barometer calibrated to show altitude instead of pressure Correct answer.
  3. A gyroscopic instrument that senses rotation about the vertical axis
  4. A rate-of-change instrument that measures vertical speed

Explanation

The altimeter contains an evacuated capsule that expands and contracts as static pressure changes, and the linkage is calibrated so the pointer shows altitude. It is therefore a barometer reading in feet rather than pressure units. Setting the subscale to the correct pressure datum is essential for accuracy.

Question 15Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The vertical speed indicator indicates climb or descent by:

  1. Comparing pitot pressure with static pressure
  2. Measuring the rate of change of static pressure through a calibrated leak Correct answer.
  3. Sensing acceleration along the aircraft's longitudinal axis
  4. Detecting the rate of rotation about the lateral axis

Explanation

The VSI has a capsule connected to static pressure and a case connected through a calibrated orifice. When altitude changes, the pressure inside the case lags behind the capsule, and the resulting differential drives the pointer. The lag also explains the brief delay before the instrument settles after a change.

Question 16Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A turn coordinator differs from a turn and slip indicator in that the turn coordinator:

  1. Operates only when the vacuum system is selected on
  2. Senses both rate of turn and rate of roll, so it indicates roll into a turn as well as turn rate Correct answer.
  3. Uses a pendulous vane rather than a gyroscope
  4. Shows the aircraft's heading directly

Explanation

The turn coordinator's gyro is canted so that it responds to yaw and to roll, allowing it to show the aircraft banking into a turn and to indicate a standard rate turn after the bank is established. A turn and slip indicator responds only to yaw rate. Both use a slip-skid ball to show coordination.

Question 17Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The heading indicator must be periodically realigned with the magnetic compass because:

  1. It is a gyroscopic instrument that drifts due to precession and earth's rotation Correct answer.
  2. Its capsule is affected by changes in altitude
  3. Its magnet is affected by the aircraft's electrical system
  4. Its static source becomes blocked in flight

Explanation

The heading indicator is a free gyroscope and does not sense north; it maintains a fixed reference in space that slowly drifts because of bearing friction, precession and the earth's rotation. The pilot therefore resets it against the magnetic compass at intervals. It is unaffected by magnetic deviation during normal operation because it has no magnet.

Question 18Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The suction gauge in a light aircraft with vacuum-driven gyroscopic instruments indicates:

  1. The cabin differential pressure
  2. The vacuum available to drive the gyroscopes Correct answer.
  3. The fuel pressure at the carburettor
  4. The pressure in the pitot system

Explanation

Vacuum-driven gyros are spun by air drawn through the instrument case by an engine-driven vacuum pump. The suction gauge shows the resulting low pressure, confirming the instruments are receiving adequate airflow. A low or zero reading warns that the attitude and heading indications may become unreliable.

Question 19Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

An aircraft's electrical system is described as a 14-volt system. Which statement best describes the relationship between the battery and the alternator in normal flight?

  1. The alternator supplies the electrical loads and charges the battery, with the battery as a standby source Correct answer.
  2. The alternator supplies only the ignition system while the battery runs the avionics
  3. The battery supplies all electrical loads and the alternator only charges it on the ground
  4. The battery and alternator share the load equally at all times

Explanation

Once the engine is running, the alternator's output voltage is set slightly above battery voltage so it carries the electrical loads and keeps the battery charged. The battery then acts as a reserve for starting and for emergencies if the alternator fails. This is why an alternator failure may not be obvious until the battery is depleted.

Question 20Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The purpose of the master switch in a light aircraft is to:

  1. Set the propeller RPM
  2. Control the fuel flow to the engine
  3. Select which magneto is active
  4. Connect or disconnect the battery and alternator from the electrical bus Correct answer.

Explanation

The master switch is usually a split switch or relay arrangement that brings the battery contactor and the alternator field onto the bus. It is the main control for the aircraft's electrical supply. Magneto selection, fuel flow and propeller RPM each have their own dedicated controls.

Question 21Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

The main structural members running lengthwise along the fuselage of a semi-monocoque aircraft are called:

  1. Spars
  2. Stringers and longerons Correct answer.
  3. Ribs
  4. Bulkheads

Explanation

Longerons are the principal longitudinal members, and stringers are lighter longitudinal stiffeners that support the skin between them. Together they carry bending loads and stabilise the skin against buckling. Formers or bulkheads give the fuselage its cross-sectional shape.

Question 22Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a semi-monocoque wing, the main bending loads are carried primarily by:

  1. The aileron hinges
  2. The spars in combination with the stressed skin Correct answer.
  3. The fabric covering
  4. The wingtip fairing

Explanation

Semi-monocoque construction uses spars as the main spanwise beams while the metal skin, stiffened by stringers and ribs, shares the bending and shear loads. This combination gives high strength for low weight. Fabric-covered wings rely on the spar and internal drag bracing rather than a stressed skin.

Question 23Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

Aircraft brakes on many light aircraft are described as independent, differential brakes. This means:

  1. The brakes operate only when the parking brake is set
  2. Both brakes are applied together by a single pedal
  3. Each main wheel brake can be applied separately by its own pedal, allowing steering on the ground Correct answer.
  4. The brakes are applied automatically when the throttle is closed

Explanation

Differential braking lets the pilot apply left or right brake independently through the rudder pedals, which assists directional control and tight turns on the ground. Applying both together provides normal braking. A parking brake valve holds pressure for parking.

Question 24Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A pilot notices that the ammeter shows a continuous high charge after start and does not return towards zero in cruise. Which interpretation is most appropriate?

  1. The magnetos are producing too much current
  2. The ammeter is indicating normal operation and no action is needed
  3. The battery is being overcharged or is failing to accept charge, so the charging system should be investigated Correct answer.
  4. The alternator has failed and the battery is supplying all loads

Explanation

After starting, a brief high charge is normal to replace the energy used by the starter, but the indication should fall back as the battery recharges. A sustained high charge suggests a regulator fault, a shorted cell or a battery that will not accept charge. Continuing flight risks overcharging and damage to the battery.

Question 25Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

During a preflight inspection, a pilot finds the fuel strainer drain produces a sample with water droplets. The correct action is to:

  1. Add a fuel additive to absorb the water
  2. Continue draining until the sample is clear of water and contamination Correct answer.
  3. Drain only the tank sumps and not the strainer
  4. Ignore it because the engine will burn the water

Explanation

Water is denser than avgas and collects at low points, so draining the strainer and tank sumps is the standard way to remove it. Draining should continue until the sample is clean and free of water or sediment. Water in the fuel can cause rough running or engine stoppage, so it must never be left in the system.

Question 26Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

Which component of a light aircraft reciprocating engine converts the reciprocating motion of the piston into rotary motion of the crankshaft?

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

Explanation

The connecting rod links the piston to the crankshaft journal. As the piston moves up and down in the cylinder, the rod swings and forces the crankshaft to rotate, producing the engine's output torque.

Question 27Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a four-stroke reciprocating engine, during which stroke is the intake valve open and the piston moving down the cylinder?

  1. The intake stroke Correct answer.
  2. The compression stroke
  3. The power stroke
  4. The exhaust stroke

Explanation

The intake stroke draws the fuel-air mixture into the cylinder. The piston travels downward while the intake valve is open, creating the low pressure that pulls the charge in from the induction system.

Question 28Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the primary function of the magneto in a light aircraft piston engine ignition system?

  1. To step the aircraft bus voltage up to a higher value
  2. To regulate the charging rate of the battery
  3. To supply current to the starter motor
  4. To produce a high-voltage spark at the spark plug at the correct time Correct answer.

Explanation

A magneto is a self-contained generator driven by the engine that produces high voltage for the spark plugs. Because it needs no battery, it keeps the engine running even if the aircraft electrical system fails.

Question 29Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a light aircraft fuel system, what is the purpose of the fuel selector valve?

  1. To automatically maintain a constant fuel pressure at the carburettor
  2. To allow the pilot to select which tank supplies the engine Correct answer.
  3. To measure the quantity of fuel remaining in each tank
  4. To drain water and sediment from the lowest point of the system

Explanation

The fuel selector valve routes fuel from a chosen tank to the engine induction system. The pilot uses it to manage fuel balance between tanks and to shut off fuel flow when required.

Question 30Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A light aircraft is fitted with a fixed-pitch propeller. Which statement best describes how engine power is controlled in cruise?

  1. Power is varied by changing manifold pressure with the throttle, and the propeller speed follows the engine Correct answer.
  2. Power is set by adjusting the propeller pitch on the ground before flight
  3. Power is controlled solely by the mixture control lever
  4. Power is set by the propeller control lever while the throttle stays fixed

Explanation

With a fixed-pitch propeller the blade angle cannot change in flight, so engine rpm is tied directly to throttle setting and airspeed. The throttle lever therefore controls both manifold pressure and propeller speed together.

Question 31Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

Why is a constant-speed propeller able to maintain a selected rpm as airspeed changes?

  1. The engine automatically reduces manifold pressure to hold rpm
  2. The blades are made of composite material that flexes with airload
  3. The propeller diameter changes with centrifugal force
  4. A governor varies blade angle to absorb the power available at the selected rpm Correct answer.

Explanation

The propeller governor senses rpm and adjusts oil pressure to change blade angle. As airspeed or power changes, blade angle is altered so the propeller absorbs exactly the power needed to hold the selected rpm.

Question 32Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

During a preflight inspection a pilot notices that the alternator warning light remains on after start-up. What is the most appropriate interpretation?

  1. The alternator is overcharging and the voltage regulator is working
  2. The charging system may not be supplying current and should be investigated before flight Correct answer.
  3. The warning light only indicates a failed starter motor
  4. The battery is fully charged and the light is a normal indication

Explanation

An alternator warning light that stays on after the engine is running suggests the charging system is not producing output. If the alternator is not charging, the battery will steadily discharge and electrical equipment may fail in flight.

Question 33Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a light aircraft electrical system, what is the function of the voltage regulator?

  1. To convert alternating current to direct current for the battery
  2. To protect the circuit from excessive current by melting
  3. To select which battery is used for starting
  4. To limit alternator or generator output voltage to a safe value Correct answer.

Explanation

The voltage regulator controls the field current so that charging-system output voltage stays within limits. This prevents overcharging the battery and protects electrical equipment from excessive voltage.

Question 34Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

An aircraft is parked overnight in freezing conditions and the pitot tube is not covered. What is the main risk on the next flight?

  1. The vertical speed indicator will show a constant climb
  2. The airspeed indicator may read incorrectly because the pitot pressure source is obstructed Correct answer.
  3. The altimeter will over-read because static pressure is trapped
  4. The heading indicator will precess rapidly

Explanation

An obstructed pitot tube prevents correct total pressure reaching the airspeed indicator. The instrument then responds only to changes in static pressure, giving misleading airspeed indications that can be dangerous.

Question 35Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What does the attitude indicator of a light aircraft use to provide a stable reference in pitch and roll?

  1. A gyroscope that remains fixed in space as the aircraft manoeuvres around it Correct answer.
  2. A magnetic sensing element aligned with the earth's field
  3. A pendulum that hangs vertically under gravity
  4. A pressure differential between the pitot and static sources

Explanation

The attitude indicator contains a gyroscope with two degrees of freedom that stays rigid in space. Because the aircraft moves around the gyro, the instrument displays pitch and roll relative to the horizon.

Question 36Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A pilot is flying straight and level and the magnetic compass shows a turn to the north while the aircraft is actually in a steady turn through north. What is the correct interpretation?

  1. The heading indicator has failed and is dragging the compass
  2. The compass is subject to turning error and the indication near north is unreliable Correct answer.
  3. The compass is showing magnetic dip error only on easterly headings
  4. The compass is serviceable and the aircraft must be turning as shown

Explanation

The magnetic compass suffers turning error that is largest when turning through north or south. Near north the compass lags or leads the turn, so it should not be used as the sole reference in a turn.

Question 37Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

An aircraft's fuel gauge indicates a quantity that does not decrease as expected during cruise. Which action is most appropriate?

  1. Continue and assume the gauge will settle as the flight progresses
  2. Switch off the fuel pump to reset the gauge
  3. Increase power to make the gauge respond
  4. Cross-check fuel remaining by dipstick or known consumption and land if quantity is in doubt Correct answer.

Explanation

A suspect fuel gauge cannot be trusted for fuel management. The pilot should verify quantity by other means such as dipstick checks or elapsed time and consumption, and plan to land if the true quantity is uncertain.

Question 38Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the purpose of the empennage on a light aircraft?

  1. To absorb landing loads through the undercarriage
  2. To provide longitudinal and directional stability and control Correct answer.
  3. To carry the main lifting loads in flight
  4. To house the engine and fuel tanks

Explanation

The empennage consists of the horizontal and vertical stabilisers with their control surfaces. It provides stability in pitch and yaw and supports the elevator and rudder used for control.

Question 39Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What are the longitudinal members of a truss-type fuselage that carry the main loads called?

  1. Stringers
  2. Longerons Correct answer.
  3. Formers
  4. Ribs

Explanation

In a truss fuselage the longerons are the main longitudinal members joined by struts and diagonal bracing. They carry bending and tension loads and form the backbone of the structure.

Question 40Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A pilot notices a slight burning smell and smoke in the cockpit during flight. What is the most appropriate initial action?

  1. Ignore it if the engine instruments remain normal
  2. Open the windows and continue to destination
  3. Identify the source, isolate the affected electrical circuit and prepare to land Correct answer.
  4. Increase electrical load to test the alternator

Explanation

Smoke or a burning smell may indicate an electrical fire. The pilot should identify and isolate the affected circuit using the appropriate switch or breaker and plan to land as soon as practicable, following the aircraft checklist.

Question 41Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the function of the aircraft's static dischargers on the trailing edges of the wings and tail?

  1. To reduce drag by smoothing airflow at the trailing edge
  2. To indicate the presence of ice on the airframe
  3. To dissipate static electricity that could interfere with radio communications Correct answer.
  4. To provide a bonding path for the lightning protection system

Explanation

Static dischargers allow accumulated static charge to bleed into the atmosphere rather than discharge as noise across the airframe. This reduces radio interference, especially in precipitation or at high altitude.

Question 42Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

Why are aircraft fuel tanks vented to atmosphere?

  1. To supply pressurised air to the carburettor
  2. To allow air to enter as fuel is used and prevent a vacuum in the tank Correct answer.
  3. To drain water from the tank in flight
  4. To allow fuel vapour to escape and reduce the octane rating

Explanation

As fuel is consumed the tank must be able to draw air in, otherwise a partial vacuum would form and could stop fuel flow. The vent also allows expansion and prevents pressure build-up during refuelling or temperature changes.

Question 43Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

In a light aircraft hydraulic brake system, what is the purpose of the brake fluid reservoir?

  1. To increase brake pressure at the wheel
  2. To cool the brake discs during landing
  3. To store compressed air for the brake system
  4. To provide a supply of hydraulic fluid and allow for expansion Correct answer.

Explanation

The reservoir holds hydraulic fluid for the brake system and accommodates changes in fluid volume. It ensures a supply is available to the master cylinder as the brakes are applied and released.

Question 44Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the purpose of the cabin heat system in a light aircraft and what risk must the pilot manage?

  1. It uses compressed air from the engine and the pilot must monitor manifold pressure
  2. It supplies heated air from around the engine exhaust and the pilot must check for carbon monoxide contamination Correct answer.
  3. It heats the cabin with electrical elements and the pilot must monitor the ammeter
  4. It circulates engine coolant through a radiator and the pilot must check coolant level

Explanation

Cabin heat is normally taken from a shroud around the exhaust or muffler and mixed with fresh air. A leak in the exhaust or heat exchanger can allow carbon monoxide into the cabin, so the pilot must check the system and use a CO detector where fitted.

Question 45Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

Which statement correctly describes the difference between a turbocharger and a normally aspirated engine in a light aircraft?

  1. A turbocharger eliminates the need for a wastegate
  2. A turbocharger uses exhaust gas energy to compress intake air and maintain power at altitude Correct answer.
  3. A turbocharger increases power only at low altitude
  4. A normally aspirated engine uses a compressor driven by the engine

Explanation

A turbocharger is driven by exhaust gas and compresses the intake charge, allowing the engine to maintain manifold pressure as altitude increases. A normally aspirated engine relies on ambient pressure and loses power with altitude.

Question 46Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the purpose of the engine air filter on a light aircraft?

  1. To silence the engine exhaust noise
  2. To cool the intake air before it reaches the cylinders
  3. To prevent dust and foreign matter entering the engine induction system Correct answer.
  4. To meter fuel into the airstream

Explanation

The air filter traps dust, sand and other particles before they enter the induction system. This protects the engine from abrasive wear, and in some installations an alternate air source bypasses the filter if it becomes blocked.

Question 47Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

A pilot notices the oil pressure gauge reading lower than normal in cruise while oil temperature remains normal. What is the most appropriate response?

  1. Continue the flight and check the gauge at the next scheduled maintenance
  2. Reduce power, monitor the indication and land as soon as practicable for investigation Correct answer.
  3. Increase power to raise oil pressure
  4. Ignore it because normal oil temperature confirms the system is healthy

Explanation

Low oil pressure can indicate a serious problem such as a pump fault, leak or blocked passage. The safest course is to reduce power to limit damage, monitor the gauge and temperature, and land as soon as practicable.

Question 48Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the function of the aircraft's stall warning device?

  1. To prevent the aircraft from entering a spin
  2. To give an audible or visual warning as the wing approaches the critical angle of attack Correct answer.
  3. To warn of low fuel pressure
  4. To indicate that the flaps are fully extended

Explanation

The stall warning device senses airflow or angle of attack and alerts the pilot before the wing reaches the stalling angle. It is an advisory device and does not physically prevent a stall.

Question 49Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

What is the main purpose of the aircraft's bonding and shielding in the electrical system?

  1. To provide a low-resistance return path and reduce radio interference Correct answer.
  2. To reduce the weight of the electrical system
  3. To allow the use of smaller circuit breakers
  4. To increase the battery charging rate

Explanation

Bonding connects metallic parts so they share a common electrical potential, providing a reliable return path and reducing static build-up. Shielding around cables reduces electromagnetic interference with radios and avionics.

Question 50Aircraft Technical (aircraft general knowledge, airframes, engines, systems and instruments)

An aircraft's tyre shows excessive wear on one side of the tread. Which factor is most likely to explain this?

  1. Incorrect camber or misalignment of the landing gear Correct answer.
  2. Incorrect tyre pressure only
  3. Over-inflation of the tyre
  4. A worn brake disc

Explanation

Uneven tread wear on one side usually points to camber or alignment problems with the landing gear. Correct tyre pressure affects overall wear pattern, but a one-sided wear pattern suggests a geometry issue.