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CAA NZ AME Subject 2: Aircraft Engineering Knowledge study materials
CAA NZ AME Subject 2: Aircraft Engineering Knowledge study resources

CAA NZ AME Subject 2: Aircraft Engineering Knowledge practice questions

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Question 1Aircraft structures, aerodynamics and flight controls

In a semi-monocoque aircraft fuselage, the primary bending loads are carried mainly by:

  1. the bulkheads and pressure deck only
  2. the transverse frames alone
  3. the skin and longitudinal stringers acting together Correct answer.
  4. the floor beams and seat rails

Explanation

Semi-monocoque construction uses the skin in tension and compression, stiffened by longitudinal stringers, to carry bending and shear. Transverse frames maintain the cross-sectional shape and support the skin but are not the primary bending path. Stringers also stabilise the skin against buckling.

Question 2Aircraft structures, aerodynamics and flight controls

For a wing at a fixed Reynolds number, increasing angle of attack from zero toward the critical angle generally causes the lift coefficient to:

  1. remain constant until the stall
  2. become negative above 5 degrees
  3. increase until the critical angle is reached Correct answer.
  4. decrease steadily to zero

Explanation

Lift coefficient rises approximately linearly with angle of attack over the normal operating range. The maximum is reached at the critical angle, after which the wing stalls and lift coefficient falls. This relationship is represented by the lift curve slope.

Question 3Aircraft structures, aerodynamics and flight controls

Movement of an aircraft about its longitudinal (roll) axis is controlled primarily by:

  1. the elevators
  2. the rudder
  3. the ailerons Correct answer.
  4. the flaps

Explanation

Ailerons are hinged to the outboard trailing edge of each wing and deflect in opposite directions to produce a rolling moment. The rudder controls yaw about the normal axis, and the elevators control pitch about the lateral axis. Flaps increase lift and drag for a given speed and do not provide primary roll control.

Question 4Aircraft structures, aerodynamics and flight controls

A structure designed to a fail-safe philosophy is intended to:

  1. retain the required residual strength after a specified failure or damage until it is detected Correct answer.
  2. operate without any inspection until a fixed retirement life is reached
  3. avoid all damage by using only high-strength steel
  4. carry limit load only if no crack is present

Explanation

Fail-safe design provides multiple load paths or crack-arrest features so that damage to one element does not cause immediate loss of the structure. The damaged structure must retain residual strength until the damage is found by inspection. Safe-life design, by contrast, retires components before fatigue cracking is expected.

Question 5Aircraft structures, aerodynamics and flight controls

For an aircraft in steady level flight at constant weight, as true airspeed increases the induced drag:

  1. remains constant because weight is unchanged
  2. decreases approximately as the inverse of the square of the speed Correct answer.
  3. increases until the critical Mach number is reached, then stays constant
  4. increases in proportion to the square of the speed

Explanation

Induced drag is associated with the lift generated by the wing and is inversely proportional to the square of the equivalent airspeed. At constant weight, a higher true airspeed requires a lower lift coefficient, so induced drag falls. Parasite drag, not induced drag, increases with the square of speed.

Question 6Aircraft structures, aerodynamics and flight controls

A servo tab fitted to a primary flight control surface assists the pilot by:

  1. moving in the same direction as the control surface and increasing the control force
  2. deflecting to create an aerodynamic moment that moves the main control surface Correct answer.
  3. measuring the control surface position for the flight data recorder
  4. locking the control surface during high-speed flight

Explanation

A servo tab is a small trailing-edge surface linked to the cockpit control. When the pilot moves the control, the tab deflects first and generates a moment that carries the main surface to the commanded position. This reduces the stick or rudder force required, particularly at high speed.

Question 7Aircraft structures, aerodynamics and flight controls

Wing sweepback is used on high-speed aircraft primarily because it:

  1. increases the wing area available for lift at low speed
  2. reduces the chordwise component of airflow, raising the critical Mach number Correct answer.
  3. prevents the formation of shock waves at any speed
  4. eliminates the need for a horizontal stabiliser

Explanation

Sweepback reduces the velocity component perpendicular to the wing leading edge, which is the component that governs compressibility effects. The critical Mach number is therefore higher than for an unswept wing of the same aerofoil. Sweep does not remove shock waves entirely; it delays their formation to a higher flight Mach number.

Question 8Aircraft structures, aerodynamics and flight controls

The retirement life of a safe-life landing gear component is determined from:

  1. fatigue testing with scatter factors applied to the tested life Correct answer.
  2. a static proof load test at 1.5 times limit load
  3. the number of landings recorded since the last overhaul only
  4. visual inspection findings at each A-check

Explanation

Safe-life components are removed from service at a fixed life derived from fatigue testing of representative specimens. Scatter factors are applied to the test life to account for variations in material, manufacture and loading. The philosophy relies on retirement before cracking is expected, not on detecting cracks by inspection.

Question 9Aircraft structures, aerodynamics and flight controls

On a swept-wing jet transport, the Mach trim system counters the tendency for the aircraft to:

  1. pitch nose-down as Mach number increases Correct answer.
  2. yaw right when thrust is increased
  3. pitch nose-up as Mach number increases
  4. roll left when the speed brake is extended

Explanation

As flight Mach number increases, the aerodynamic centre of a swept wing moves aft, producing a nose-down pitching moment often called tuck-under. The Mach trim system applies a gradual nose-up elevator command to compensate. It operates without pilot input and is separate from the stall warning system.

Question 10Aircraft structures, aerodynamics and flight controls

Wingtip vortices are generated because the wing:

  1. has higher pressure below the wing than above, causing flow to curl around the tip Correct answer.
  2. accelerates air rearward across the whole span uniformly
  3. operates at a negative angle of attack at the tip
  4. uses a symmetrical aerofoil section at the root

Explanation

The pressure difference between the lower and upper surfaces drives air outward under the wing and inward over the top. At the tip this flow curls into a trailing vortex, strongest when the wing is heavily loaded and slow. The vortices form part of the aircraft's induced drag.

Question 11Aircraft structures, aerodynamics and flight controls

In a conventional metallic wing, the ribs are primarily provided to:

  1. maintain the aerofoil contour and support the skin and stringers Correct answer.
  2. provide the main torsional stiffness of the wing box
  3. carry the wing bending loads into the fuselage attachment
  4. act as the primary attachment for the engine pylon

Explanation

Ribs maintain the aerofoil contour, support the skin and stringers, and transfer local loads to the spars. They also help prevent skin buckling between stringers. Bending is carried mainly by spar caps and skin, while torsional stiffness comes from the closed wing box.

Question 12Aircraft structures, aerodynamics and flight controls

Compared with a laminar boundary layer, a turbulent boundary layer on an aircraft wing:

  1. has lower skin-friction drag but separates more readily
  2. exists only at supersonic speeds
  3. has no effect on skin-friction drag or separation
  4. has higher skin-friction drag but resists separation better Correct answer.

Explanation

A turbulent boundary layer has more kinetic energy near the surface, so it resists separation better than a laminar layer. However, the mixing also produces higher skin-friction drag. Laminar flow gives lower friction but separates more easily.

Question 13Aircraft structures, aerodynamics and flight controls

When deployed in flight, wing spoilers primarily:

  1. spoil lift and increase drag Correct answer.
  2. trim the aircraft in pitch
  3. provide yaw control during crosswind landings
  4. increase wing lift and reduce drag

Explanation

Spoilers disrupt the smooth airflow over the wing, reducing lift and increasing drag. They are used for glidepath control, speedbraking, roll control and ground lift dumping. They do not normally provide pitch trim or yaw control.

Question 14Aircraft structures, aerodynamics and flight controls

For a thin-walled cylindrical fuselage pressurized to a constant internal pressure, the hoop stress is:

  1. half the longitudinal stress
  2. zero at the centre of the skin
  3. approximately twice the longitudinal stress Correct answer.
  4. equal to the longitudinal stress

Explanation

For a thin-walled cylinder, hoop stress is pr/t and longitudinal stress is pr/2t, so hoop stress is approximately twice the longitudinal stress. The ratio applies away from local discontinuities and reinforcements. Hoop stress is not zero at the skin centre.

Question 15Aircraft structures, aerodynamics and flight controls

Differential ailerons are rigged so that the upward-deflecting aileron moves through a larger angle than the downward-deflecting aileron in order to:

  1. increase the roll rate at low speed
  2. reduce adverse yaw from the down-going wing Correct answer.
  3. prevent aileron flutter at high speed
  4. provide pitch trim without using the elevator

Explanation

The down-going aileron increases lift but also increases induced drag, producing adverse yaw. Differential gearing reduces the downward deflection, so the drag increase on that wing is smaller. This reduces adverse yaw without reversing the roll command.

Question 16Aircraft structures, aerodynamics and flight controls

In a single-row lap joint loaded in tension, each rivet primarily resists:

  1. bending across its head
  2. torsion about its axis
  3. tension along its shank
  4. shear across its shank Correct answer.

Explanation

In a lap joint, the rivets connect two overlapping sheets, so the applied tension is transferred as shear across each rivet shank. The sheet also experiences bearing stress around the holes. Rivet tension, bending and torsion are not the primary load paths in this joint.

Question 17Aircraft structures, aerodynamics and flight controls

The critical Mach number of an aerofoil is the free-stream Mach number at which:

  1. the aircraft first encounters low-speed buffet
  2. local airflow first reaches Mach 1 on the aerofoil Correct answer.
  3. the wing reaches its maximum lift coefficient in steady flight
  4. drag divergence begins at the wing root

Explanation

The critical Mach number is reached when the fastest local flow over the aerofoil first becomes sonic, even though the free-stream flow is still subsonic. Drag divergence and buffet typically occur at or above this condition. Maximum lift and initial buffet are separate aerodynamic events.

Question 18Aircraft structures, aerodynamics and flight controls

Control surfaces are mass-balanced to move their centre of gravity:

  1. below the hinge line to improve static stability
  2. at the hinge or ahead to reduce flutter Correct answer.
  3. to the wing tip to improve roll response
  4. aft of the hinge line to increase control feel

Explanation

Mass balancing places the control surface centre of gravity at or ahead of the hinge line. This reduces the inertia coupling that can feed flutter. An aft centre of gravity increases flutter risk rather than improving feel.

Question 19Aircraft structures, aerodynamics and flight controls

In a wing torsion box, the primary function of the spar web is to carry:

  1. shear between the spar caps Correct answer.
  2. the wing's fuel pressure loads
  3. the concentrated engine thrust
  4. bending tension and compression

Explanation

The spar caps carry the bending tension and compression, while the spar web carries the shear flow between them. Together with the skin, the web completes the torsion box and carries torsional shear. Fuel pressure and engine thrust are carried by other structure.

Question 20Aircraft structures, aerodynamics and flight controls

In a fly-by-wire flight control system, dissimilar redundancy is used to:

  1. reduce the number of computers required for dispatch
  2. allow manual reversion to direct cable control
  3. increase the control surface deflection rate
  4. prevent a common-mode failure affecting all lanes Correct answer.

Explanation

Dissimilar redundancy uses different hardware and software designs in redundant lanes so that a single design fault cannot disable every lane. This protects against common-mode failures. Identical redundant lanes alone are vulnerable to the same latent fault.

Question 21Aircraft structures, aerodynamics and flight controls

In New Zealand civil aircraft structural design, the ultimate load that a structure must withstand is normally expressed as a factor of safety applied to the limit load. What is that factor?

  1. 1.0
  2. 2.0
  3. 1.5 Correct answer.
  4. 1.15

Explanation

The limit load is the maximum load expected in service. The ultimate load is normally 1.5 times the limit load, and the structure must be able to withstand this ultimate load without failure.

Question 22Aircraft structures, aerodynamics and flight controls

In a semi-monocoque fuselage, the longitudinal members that stiffen the skin and carry axial bending loads are called:

  1. stringers Correct answer.
  2. bulkheads
  3. frames
  4. ribs

Explanation

Stringers run lengthwise along the fuselage and, together with the skin, carry axial bending loads while stiffening the skin against buckling. Frames and bulkheads are transverse members that maintain shape and carry concentrated loads.

Question 23Aircraft structures, aerodynamics and flight controls

Two wings have the same planform area and lift coefficient. The wing with the higher aspect ratio will produce:

  1. less induced drag Correct answer.
  2. the same induced drag
  3. more parasite drag at all speeds
  4. more induced drag

Explanation

Induced drag coefficient is proportional to the square of the lift coefficient divided by aspect ratio and span efficiency. A higher aspect ratio weakens the tip vortices and therefore reduces induced drag for the same lift coefficient and area.

Question 24Aircraft structures, aerodynamics and flight controls

For a conventional cambered aerofoil operating below the stall angle, increasing angle of attack generally causes the centre of pressure to:

  1. move rearward toward the trailing edge
  2. move forward toward the leading edge Correct answer.
  3. remain fixed at the trailing edge
  4. remain fixed at 50% chord

Explanation

Below the stall, increasing angle of attack shifts the lift distribution toward the leading edge on a conventional cambered aerofoil. This moves the centre of pressure forward, although the movement is not fixed and changes near the stall.

Question 25Aircraft structures, aerodynamics and flight controls

An aircraft with positive wing dihedral sideslips to the right. The resulting rolling moment is:

  1. to the right, increasing the sideslip
  2. to the left only if the wing is swept
  3. to the left, opposing the sideslip Correct answer.
  4. zero because dihedral does not affect roll

Explanation

With positive dihedral, a sideslip to the right increases the angle of attack of the right wing relative to the left wing. The right wing therefore produces more lift and the aircraft rolls left, which opposes the sideslip and gives lateral stability.

Question 26Aircraft structures, aerodynamics and flight controls

The shear centre of an aircraft wing section is the point through which a transverse shear load must act to produce:

  1. maximum bending moment
  2. no twisting of the section Correct answer.
  3. pure axial tension
  4. maximum torsional stiffness

Explanation

The shear centre is the point in a cross-section through which a transverse shear load produces bending without torsion. If the load acts away from the shear centre, the offset creates a twisting moment on the section.

Question 27Aircraft structures, aerodynamics and flight controls

In a fully powered flight control system, artificial feel is incorporated to:

  1. automatically trim the aircraft after flap selection
  2. prevent the control surfaces from fluttering
  3. increase hydraulic system pressure at high speed
  4. provide feel forces that vary with airspeed Correct answer.

Explanation

Powered controls remove most of the natural hinge moment, so artificial feel devices such as springs or q-feel units generate resistance that increases with control deflection and airspeed. This prevents overcontrolling and gives the pilot useful feedback.

Question 28Aircraft structures, aerodynamics and flight controls

In a damage-tolerant aircraft structure, scheduled inspections are intended primarily to:

  1. find cracks before they reach critical size Correct answer.
  2. replace parts before their safe-life expires
  3. prove the structure has unlimited life
  4. prevent any crack from forming

Explanation

Damage tolerance assumes that cracks may exist and uses scheduled inspections to find them before they grow to a size that reduces residual strength below the required limit load. The inspection interval is based on crack growth analysis and detectable crack size.

Question 29Aircraft structures, aerodynamics and flight controls

At high true airspeed, a wing with torsional flexibility may experience aileron reversal because downward aileron deflection:

  1. adds lift aft of the torsional axis, twisting the wing nose-down Correct answer.
  2. removes lift behind the torsional axis and twists the wing nose-up
  3. has no aerodynamic effect above the critical Mach number
  4. moves the centre of pressure onto the shear centre

Explanation

A downward-deflected aileron increases lift behind the torsional axis of a flexible wing. At high speed this lift can twist the wing leading edge down, reducing the local angle of attack and eventually reversing the intended rolling moment.

Question 30Aircraft structures, aerodynamics and flight controls

As a swept-wing jet accelerates above its critical Mach number, shock-induced separation over the rear of the wing can produce a nose-down pitching moment known as:

  1. aileron reversal
  2. wing divergence
  3. Mach tuck Correct answer.
  4. Dutch roll

Explanation

Mach tuck is a nose-down pitching tendency that can occur as shock-induced flow changes move the aerodynamic centre aft and alter lift distribution above the critical Mach number. It is a high-speed compressibility effect, not a lateral-directional oscillation.

Question 31Aircraft structures, aerodynamics and flight controls

A wing is built with geometric washout. The purpose of this design feature is to:

  1. keep the whole wing at a constant incidence from root to tip so that the stall is uniform
  2. increase the lift produced at the tip at high angle of attack so that the ailerons stay effective
  3. make the root reach the critical angle of attack before the tip, preserving aileron effectiveness Correct answer.
  4. twist the tip to a higher incidence than the root so that the tip stalls first

Explanation

Washout is a built-in twist in which the tip is set at a lower incidence than the root. As angle of attack increases, the root therefore reaches its critical angle first, leaving the tip and its ailerons below the stall so that lateral control is retained. The opposite arrangement, wash-in, promotes tip stall and wing drop.

Question 32Aircraft structures, aerodynamics and flight controls

Compared with a plain flap of the same chord, a Fowler flap when extended:

  1. moves rearward without changing camber, so the critical angle of attack is unaffected
  2. increases wing camber and effective area, raising the maximum lift coefficient Correct answer.
  3. decreases wing camber but increases area, so the lift curve slope is unchanged
  4. increases camber only, so the wing area and stalling speed remain unchanged

Explanation

A Fowler flap first translates aft on tracks and then hinges downwards, so it increases wing area as well as camber. The combination of greater area and greater camber produces a higher maximum lift coefficient than a plain flap of the same chord, and therefore a lower stalling speed.

Question 33Aircraft structures, aerodynamics and flight controls

In a pressurized transport aeroplane fuselage, fatigue cracking of the skin is most likely to begin at:

  1. rivet holes and cut-out corners, where local stress concentrations exist Correct answer.
  2. regions where the skin is bonded over a large continuous area with no change in section
  3. the point of minimum principal stress on the pressure hull
  4. the mid-span of a large unstiffened skin panel remote from any joint

Explanation

Fatigue cracks initiate where the local stress is raised above the nominal level, typically at rivet holes, fastener rows, door and window cut-outs and abrupt changes of section. At these stress concentrations the cyclic stress range from pressurization cycles is greatest, so they govern the inspection programme.

Question 34Aircraft structures, aerodynamics and flight controls

A single-cell thin-walled wing torsion box has an enclosed area of 0.6 m² and carries a torque of 30 kN·m. The shear flow in the walls is:

  1. 12.5 kN/m
  2. 50 kN/m
  3. 90 kN/m
  4. 25 kN/m Correct answer.

Explanation

For a thin-walled closed cell under pure torsion the shear flow is constant around the wall and is given by q = T/(2A), where A is the area enclosed by the mean line of the wall. Substituting gives q = 30 000 N·m / (2 × 0.6 m²) = 25 000 N/m, that is 25 kN/m.

Question 35Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

In a pressurised aircraft hydraulic system, the reservoir is normally pressurised with air or nitrogen in order to:

  1. Prevent pump inlet cavitation at altitude Correct answer.
  2. Raise system pressure above the relief valve setting
  3. Cool the fluid before it returns to the reservoir
  4. Remove suspended air by centrifugal separation

Explanation

Reservoir pressurisation maintains a positive feed pressure at the pump inlet so the pump does not cavitate, particularly at high altitude or low temperature. The pressurisation source is usually regulated air or nitrogen and is not the means of setting system pressure.

Question 36Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Phosphate-ester hydraulic fluid, such as Skydrol, is dyed which colour to distinguish it from mineral-based fluid?

  1. Blue
  2. Red
  3. Green
  4. Purple Correct answer.

Explanation

Phosphate-ester fluid is dyed purple, while mineral-based fluid is typically dyed red. The colour coding helps maintenance personnel avoid mixing incompatible fluids, which can damage seals and system components.

Question 37Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Which of the following is a thermal anti-icing method used on the wing leading edge of a transport aeroplane?

  1. Electrically heating the rear spar
  2. Ducting hot bleed air through the leading edge Correct answer.
  3. Inflating rubber boots to crack the ice
  4. Spraying glycol from a weeping wing

Explanation

Thermal wing anti-icing uses hot engine bleed air ducted through the leading-edge structure to keep the surface above freezing. This prevents ice formation rather than removing ice after it has formed.

Question 38Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

In a typical two-stage bleed air system on a turbofan engine, the high-pressure (HP) bleed valve is commanded open when the:

  1. Low power with IP bleed pressure below nominal Correct answer.
  2. Ground pressurisation test with outflow valve closed
  3. Air-conditioning packs selected off by the crew
  4. High power with IP bleed pressure above nominal

Explanation

The HP bleed valve opens at low engine speed when IP stage pressure is too low to meet the bleed demand. As engine speed rises and IP pressure becomes sufficient, the HP valve closes to avoid overpressure.

Question 39Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

The fuel tank vent system on a large transport aeroplane primarily:

  1. Separates water from fuel before it reaches the feed line
  2. Prevents fuel flowing to the engines if a boost pump fails
  3. Provides pressurisation to drive fuel through the boost pumps
  4. Keeps tank pressure near ambient as fuel and altitude change Correct answer.

Explanation

The vent system keeps tank pressure close to ambient as fuel is consumed and as the aircraft climbs or descends. This prevents structural overpressure or underpressure and allows fuel to feed and transfer normally.

Question 40Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

During automatic cabin pressure control, the outflow valve regulates cabin altitude by:

  1. Changing the speed of the cabin air compressor
  2. Opening the pressurisation safety relief valves
  3. Varying the effective outflow area from cabin to atmosphere Correct answer.
  4. Adjusting the bleed air temperature entering the cabin

Explanation

The outflow valve varies the area through which cabin air leaves to atmosphere. Opening it increases outflow and lowers cabin pressure; closing it reduces outflow and raises cabin pressure.

Question 41Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Before checking the nitrogen precharge pressure of a hydraulic accumulator, the correct procedure is to:

  1. Run the system pump until the accumulator is fully charged
  2. Open the accumulator bleed valve with the system at full pressure
  3. Depressurise the hydraulic system and isolate the accumulator from pressure Correct answer.
  4. Heat the hydraulic fluid to normal operating temperature

Explanation

Accumulator precharge is measured with hydraulic pressure removed so the nitrogen charge alone is indicated. If the system is pressurised, the hydraulic fluid compresses the nitrogen and the gauge reading is not the true precharge.

Question 42Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Water contamination in an aircraft fuel tank is normally checked for by:

  1. Measuring fuel temperature at the fuel control unit
  2. Checking the fuel pressure warning light in climb
  3. Reading fuel flow during engine start
  4. Draining tank sumps and checking for free water Correct answer.

Explanation

Water is denser than fuel and collects at the low points, so sump drains are sampled. Free water or a cloudy appearance indicates contamination that must be removed before flight.

Question 43Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Which of these ice protection systems is classed as de-icing rather than anti-icing?

  1. TKS weeping wing distributing glycol over the leading edge
  2. Pneumatic rubber boots that inflate to crack accumulated ice Correct answer.
  3. Wing leading-edge thermal anti-ice using bleed air
  4. Electrically heated pitot mast

Explanation

De-icing removes ice after it has formed, whereas anti-icing prevents formation. Pneumatic boots inflate to crack and shed accumulated ice, while thermal, electrical and weeping-wing systems normally prevent ice from forming.

Question 44Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

In a bootstrap air cycle air-conditioning system, the secondary heat exchanger is used to:

  1. Remove heat from ACM-compressed air before turbine entry Correct answer.
  2. Add moisture to the conditioned air before cabin entry
  3. Reduce bleed pressure to cabin altitude before cooling
  4. Drive the ACM turbine directly with engine bleed air

Explanation

In a bootstrap air cycle machine the bleed air is compressed by the ACM compressor, which raises its temperature. The secondary heat exchanger removes that heat before the air expands through the turbine, producing cold conditioned air.

Question 45Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

In an aircraft hydraulic system, what is the primary function of the system pressure relief valve?

  1. It holds pump outlet pressure constant as pump speed changes.
  2. It limits maximum system pressure by returning excess fluid to the return line. Correct answer.
  3. It isolates the system from the reservoir when the engine is shut down.
  4. It removes entrained air from the fluid before it reaches the actuators.

Explanation

A pressure relief valve is a safety device that opens at a preset pressure and bypasses excess flow to the return line or reservoir. It protects lines, seals and components from overpressure but does not regulate normal pump output, de-aerate fluid or act as a shutoff valve.

Question 46Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Which fuel system component delivers fuel under positive pressure to the inlet of the engine-driven fuel pump and helps prevent vapour lock at high altitude?

  1. The fuel tank vent check valve
  2. The fuel flow transmitter
  3. The fuel boost pump Correct answer.
  4. The fuel shutoff valve

Explanation

A fuel boost pump raises fuel pressure at the engine pump inlet, suppressing vapour lock and providing a backup supply if the engine pump suction feed is inadequate. The shutoff valve only opens or closes the supply, the flow transmitter measures flow, and the vent check valve admits air to the tank.

Question 47Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

On a transport aeroplane, a windscreen wiper system is provided as part of which protection function?

  1. Chemical de-icing
  2. Thermal anti-icing
  3. Rain removal Correct answer.
  4. Pneumatic de-icing

Explanation

Windscreen wipers mechanically clear rain, snow and spray from the windscreen so the crew can see. They do not prevent ice formation or remove accumulated ice, so they are classified as rain removal rather than anti-icing or de-icing.

Question 48Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

In a hydraulic system, an accumulator with a nitrogen precharge is installed mainly to:

  1. Filter solid contaminants from the fluid during normal operation.
  2. Provide a reserve of fluid to make up for normal internal leakage.
  3. Store hydraulic energy for peak demands and damp pressure surges. Correct answer.
  4. Cool the hydraulic fluid by transferring heat into the nitrogen.

Explanation

The nitrogen precharge is compressed when fluid enters the accumulator, storing energy that can supplement pump output during peak actuator demands and absorb pressure pulsations. It is not a filter, a heat exchanger, or a normal leakage make-up reservoir.

Question 49Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

In a high-pressure bleed-air system, the precooler is used to:

  1. Remove water vapour from the bleed air before it reaches the air-conditioning packs.
  2. Reduce the bleed air temperature before it is supplied to the air-conditioning packs. Correct answer.
  3. Supply pressurisation air directly to the cabin without further conditioning.
  4. Regulate bleed air pressure to a constant value regardless of engine power.

Explanation

A precooler is an air-to-air heat exchanger that uses fan air to cool hot engine bleed air before it enters the pack or other downstream systems. Pressure regulation is done by a pressure-regulating valve, and water removal occurs later in the pack.

Question 50Airframe systems (hydraulic, pneumatic, fuel, ice and rain protection, cabin environment)

Some large transport aeroplanes are fitted with a fuel jettison system so that the crew can:

  1. Transfer fuel between tanks to correct lateral imbalance.
  2. Reduce the aeroplane weight to or below maximum landing weight. Correct answer.
  3. Increase fuel flow to the engines during take-off.
  4. Remove suspended water and sediment from the fuel.

Explanation

A fuel jettison system dumps fuel overboard at a controlled rate so that the aeroplane can land at or below its maximum landing weight after an emergency or abnormal situation. It is not a tank transfer, fuel-cleaning or engine feed system.