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The purpose of cabin air flow control valves in a pressurization system is to ? [ Control visibility ]

Question 24-1 : Maintain a constant and sufficient mass air flow to ventilate the cabin and minimise cabin pressure surges regulate cabin pressure to the selected altitude discharge cabin air to atmosphere if cabin pressure rises above the selected altitude regulate cabin pressure at the maximum cabin pressure differential

Cabin pressurization is controlled during all phases of airplane operation by the cabin pressure control system .the system uses bleed air supplied to and distributed by the air conditioning.system pressurization and ventilation are controlled by modulating the outflow valve and the overboard exhaust valve . pressurization outflow .cabin air outflow is controlled by the outflow valve and the overboard exhaust valve a small amount is also exhausted through toilet and galley vents miscellaneous fixed vents and by seal leakage . outflow valve .the outflow valve is the overboard exhaust exit for the majority of the air.circulated through the passenger cabin passenger cabin air is drawn through foot level grills down around the aft cargo compartment where it provides heating and is discharged overboard through the outflow valve . note for the answer discharge cabin air to atmosphere if cabin pressure rises above the selected altitude we are talking about the pressure relief valves who provide safety pressure relief by limiting the differential pressure to a maximum of 9 1 psi a negative relief valve prevents external atmospheric pressure from exceeding internal cabin pressure exemple 124 Maintain a constant and sufficient mass air flow to ventilate the cabin and minimise cabin pressure surges.Maintain a constant and sufficient mass air flow to ventilate the cabin and minimise cabin pressure surges.

If the pressure in the cabin tends to become lower than the outside ambient air ?

Question 24-2 : Negative pressure relief valve will open negative pressure relief valve will close air cycle machine will stop outflow valve open completely

All pressurised aircraft have negative pressure relief valves that will open and enable cabin pressure to increase at the same rate as ambient pressure should the cabin/ambient differential try to go negative .aircraft are structurally designed for a positive differential cabin pressure higher than ambient .under normal operation the pressure controller can cope but in emergencies the negative pressure relief valves will function exemple 128 Negative pressure relief valve will open.Negative pressure relief valve will open.

Cabin air for cs 25 aeroplanes is usually taken from ?

Question 24-3 : The high pressure compressor and from the low pressure compressor if necessary the low pressure compressor the second fan stage the high pressure compressor

The air is taken from the engine at a suitable pressure and temperature from the compressors on a modern high bypass engine that would mean the high pressure compressor but it is really dependant on type exemple 132 The high pressure compressor and from the low pressure compressor if necessary.The high pressure compressor and from the low pressure compressor if necessary.

Under normal flight conditions cabin pressure is controlled by ?

Question 24-4 : Regulating the discharge of air through the outflow valve s pressurisation duct relief valve s engine rpm inward relief valve s

exemple 136 Regulating the discharge of air through the outflow valve(s).Regulating the discharge of air through the outflow valve(s).

Pneumatic mechanical ice protection systems are mainly used for ?

Question 24-5 : Wings pitot tubes propellers windscreens

Pneumatic mechanical ice protection systems are mainly used for wings more precisely for leading edge wing and tail surfaces .this is a de icing system only it has to be turn on after a bit of ice has build up . 863.when activated rubber boots are pressurized with air and they expand breaking ice off the leading edge surfaces . 864 exemple 140 Wings.Wings.

With regard to pneumatic mechanical devices that afford ice protection the only ?

Question 24-6 : They can only be used as de icing devices they can only be used as anti icing devices they are used extensively on modern aircraft as they are inexpensive and easy to maintain they can be used as both de icing and anti icing devices

exemple 144 They can only be used as de-icing devices.They can only be used as de-icing devices.

Concerning electrically powered ice protection devices the only true statement ?

Question 24-7 : On modern aircraft electrically powered thermal devices are used to prevent icing on small surfaces pitot static windshield on modern aircraft electrically powered thermal devices are used as de icing devices for pitot tubes static ports and windshield on modern aircraft electrically powered thermal devices are very efficient therefore they only need little energy on modern aircraft electrical power supply being available in excess this system is very often used for large surfaces de icing

exemple 148 On modern aircraft, electrically powered thermal devices are used to prevent icing on small surfaces (pitot-static, windshield...).On modern aircraft, electrically powered thermal devices are used to prevent icing on small surfaces (pitot-static, windshield...).

The elements specifically protected against icing on transport aircraft are .1 ?

Question 24-8 : 1 2 4 and 5 1 4 5 and 7 1 2 5 and 6 1 2 3 and 8

exemple 152 1, 2, 4 and 5.1, 2, 4 and 5.

The wing anti ice system has to protect ?

Question 24-9 : The leading edge or the slats either partially or completely the whole upper wing surface and the flaps the whole leading edge except the slats because they cannot be de iced when extended the whole leading edge and the whole under wing surface

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor . 865.the wing anti ice system has to protect the leading edge or the slats either partially or completely the engine intake the frontal area of the elevator and the vertical stabiliser exemple 156 The leading edge or the slats, either partially or completely.The leading edge or the slats, either partially or completely.

In jet aeroplanes the 'thermal anti ice system' is primarily supplied by ?

Question 24-10 : Bleed air from the engines turbo compressors ram air heated via a heat exchanger the apu

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor . 865.the wing anti ice system has to protect the leading edge or the slats either partially or completely the engine intake the frontal area of the elevator and the vertical stabiliser exemple 160 Bleed air from the engines.Bleed air from the engines.

The de icing system which is mostly used for the wings of modern turboprop ?

Question 24-11 : Pneumatic boots fluid de icing thermal anti icing electrical heating

exemple 164 Pneumatic boots.Pneumatic boots.

Concerning the sequential pneumatic impulses used in certain leading edge de ?

Question 24-12 : 2 and 3 1 and 3 1 and 4 2 and 4

exemple 168 2 and 32 and 3

Generally for large aeroplanes electrical heating for ice protection is used on ?

Question 24-13 : Pitot tubes elevator leading edges slat leading edges fin leading edges

exemple 172 Pitot tubes.Pitot tubes.

The wing ice protection system currently used for most large jet transport ?

Question 24-14 : Hot air system electrical de icing system pneumatic system with inflatable boots liquid de icing system

On most modern jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor . 865.the wing anti ice system has to protect the leading edge or the slats either partially or completely the engine intake the frontal area of the elevator and the vertical stabiliser exemple 176 Hot air system.Hot air system.

Pneumatic mechanical devices that provide ice protection ?

Question 24-15 : Are usually used as de icing devices require large quantities of bleed air can only be used as anti icing devices are usually used on aeroplanes equipped with turbo fan engines

The anti icing method for the wings of large jet transport aeroplanes most ?

Question 24-16 : Thermal use of hot air chemical glycol based liquid electrical electrical resistance mechanical pneumatic boots

In large jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor . 865.the wing anti ice system has to protect the leading edge or the slats either partially or completely the engine intake the frontal area of the elevator and the vertical stabiliser exemple 184 Thermal (use of hot air).Thermal (use of hot air).

Windshield heating of a transport aeroplane is ?

Question 24-17 : Essential to improve the strength of the cockpit windows not affecting the strength of a cockpit windows only used when hot air demisting is insufficient used only at low altitudes where there is a risk of ice formation

Windshield heating system employs a windscreen of special laminated construction heated electrically to prevent not only the formation of ice and mist but also to improve the impact resistance of the windscreen at low temperatures

The heat for the anti icing system of a turbofan engine intake is provided by ?

Question 24-18 : Bleed air from the hp compressor bleed air from the lp compressor the electrical system of the aircraft a dedicated generator on the gearbox of that engine

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor . 865.the wing anti ice system has to protect the leading edge or the slats either partially or completely the engine intake the frontal area of the elevator and the vertical stabiliser exemple 192 Bleed air from the hp compressor.Bleed air from the hp compressor.

The use of a hot air wing anti icing system ?

Question 24-19 : Does not affect aerodynamic performance of the wing and causes a reduction in maximum thrust does not affect aerodynamic performance of the wing and causes no reduction in maximum thrust reduces aerodynamic performance of the wing and causes no reduction in maximum thrust reduces aerodynamic performance of the wing and causes a reduction in maximum thrust

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor . 865.the wing anti ice system has to protect the leading edge or the slats either partially or completely the engine intake the frontal area of the elevator and the vertical stabiliser .since hot air is tapped directly from a compressor stage the temperature will rise in the turbine which can limit thrust in order not to exceed the maximum engine temperature exemple 196 Does not affect aerodynamic performance of the wing and causes a reduction in maximum thrust.Does not affect aerodynamic performance of the wing and causes a reduction in maximum thrust.

Ice formation on turbofan engine intakes is usually ?

Question 24-20 : Prevented by using compressor bleed air removed by using pneumatic boots prevented by using turbine bleed air removed by using electrical heating

exemple 200 Prevented by using compressor bleed air.Prevented by using compressor bleed air.

The ice protection for propellers of modern turboprop aeroplanes works ?

Question 24-21 : Electrically pneumatically with hot air with anti icing fluid

Admin .ice formation on a propeller blade produces distortion to the aerofoil section causing a loss in efficiency possible unbalance and destructive vibration .the build up of ice must be prevented and there are two systems in use .protection is provided either by an anti icing fluid system or by an electrically powered thermal de icing system . on modern turboprop cessna caravan pilatus pc 12 beechcraft 90 to 1900d dash 8 atr 42/72 etc the ice protection for propellers works electrically .in electrical systems the basis for effective de icing is formed by resistance wire heating elements bonded to the leading edges of the propeller blades in the case of turbine engine propellers wire woven or sprayed elements are also bonded to the front shell of the spinner depending on the type of aircraft the power for heating the elements is either direct current or alternating current and is applied in a controlled sequence by a cyclic timer unit in turbo propeller engine installations the propeller heating circuit forms part of a power unit de icing and anti icing system and the cyclic control is integrated with the engine air intake heating circuit . 866. 867.cessna 208 caravan exemple 204 Electrically.Electrically.

The heating facility for the windshield of an aircraft is ?

Question 24-22 : Used on a continual basis as it reduces the thermal gradients which adversely affect the useful life of the components harmful to the integrity of the windows in the event of a bird strike only used when hot air demisting is insufficient used only at low altitudes where there is a risk of ice formation

Howarthson .the window heating system is selected permanently on but the heating elements are actually cycled on/off to maintain a constant temperature of the window .by keeping the window warm not only keeps it clear of ice but increases its resistance to impact damage exemple 208 Used on a continual basis as it reduces the thermal gradients which adversely affect the useful life of the components.Used on a continual basis as it reduces the thermal gradients which adversely affect the useful life of the components.

The wing ice protection system currently used for most large turboprop ?

Question 24-23 : A pneumatic system with inflatable boots an electrical de icing system a hot air system a liquid de icing system

On most turboprops this is a de icing system inflatable boots . 864 exemple 212 A pneumatic system with inflatable boots.A pneumatic system with inflatable boots.

Electrically powered ice protection devices on aircraft are ?

Question 24-24 : Used as anti icing devices for pitot tubes static ports and windshield used for large surfaces only used primarily because they are very efficient used as de icing devices for pitot tubes static ports and windshield

exemple 216 Used as anti-icing devices for pitot-tubes, static ports and windshield.Used as anti-icing devices for pitot-tubes, static ports and windshield.

On most transport aircraft the low pressure pumps of the fuel system are ?

Question 24-25 : Centrifugal pumps driven by an electric motor removable only after the associated tank has been emptied mechanically driven by the engine's accessory gearbox electro mechanical wobble pumps with self regulated pressure

The pumps in question are the pumps in the fuel tanks they are known as 'lp pumps' and also 'booster pumps' less than 3 bars 40 psi .engine driven pumps would come under engine fuel system the dividing line being made at the low pressure cock or valve exemple 220 Centrifugal pumps, driven by an electric motor.Centrifugal pumps, driven by an electric motor.

The fuel supply system on a jet engine includes a fuel heating device upstream ?

Question 24-26 : Prevent at low fuel temperature the risk of ice formation from water contained in the fuel maintain and improve fuel heating power ease low pressure pumps work by increasing fuel fluidity prevent fuel from freezing in fuel pipes due to low temperatures at high altitude

exemple 224 Prevent, at low fuel temperature, the risk of ice formation from water contained in the fuel.Prevent, at low fuel temperature, the risk of ice formation from water contained in the fuel.

On most transport jet aircraft the low pressure pumps of the fuel system are ?

Question 24-27 : 115 v ac 28 v ac 28 v dc 115 v dc

Fuel is delivered under pressure from fuel pumps located in the fuel tanks this 115 v ac powered fuel pumps are cooled and lubricated by fuel passing through the pump . notice fuel pump pressure should be supplied to the engines at all times at high altitude without fuel pump pressure thrust deterioration or engine flameout may occur exemple 228 115 v ac.115 v ac.

The pressure usually produced by the booster pumps of the fuel supply system of ?

Question 24-28 : 20 to 50 psi 5 to 10 psi 3000 to 5000 psi 300 to 500 psi

exemple 232 20 to 50 psi.20 to 50 psi.

In a gas turbine engine lubrication system the oil to fuel heat exchanger ?

Question 24-29 : Oil cooling through thermal exchange with the fuel fuel cooling to prevent vapour locking interrupting the fuel supply to the nozzles automatic controlled fuel heating by engine oil to prevent icing in the fuel filter fuel heating as required whenever fuel filter clogging is detected

exemple 236 Oil cooling through thermal exchange with the fuel.Oil cooling through thermal exchange with the fuel.

The fuel cross feed system ?

Question 24-30 : Allows feeding of any engine from any fuel tank is only used to feed an engine from the tank of the opposite wing is only used on the ground for fuel transfer from one tank to another is only used in flight for fuel transfer from one tank to another

The engine fuel manifolds are interconnected by use of the crossfeed valve fuel pressure can be provided from a any fuel tank with operating fuel pumps to both engines by opening the fuel crossfeed valve .continued crossfeed can result in a progressive fuel imbalance exemple 240 Allows feeding of any engine from any fuel tank.Allows feeding of any engine from any fuel tank.

The purpose of baffles in an aeroplane's integral fuel tank is to ?

Question 24-31 : Restrict the fuel movements in the tank prevent overpressure in the tank prevent the fuel from flowing in the vent lines prevent mixture of the fuel and hydraulic fluid

Baffles in a fuel tank are a series of partitions wall to control the rapid flow of fuel and prevent its sloshing these partitions have holes that allow the fuel to feed to the tank outlet but they keep the fuel from surging enough to uncover the fuel outlet exemple 244 Restrict the fuel movements in the tank.Restrict the fuel movements in the tank.

On a transport type aircraft the fuel tank system is vented through ?

Question 24-32 : Ram air scoops on the underside of the wing a pressure regulator in the wing tip bleed air from the engines the return lines of the fuel pumps

This question refers to the vent/pressurisation system used on the b737 it is a little misleading in that the tank ventilation and pressurisation systems are combined .the ram air scoop on the lower surface of the leading edge delivers air at pressure to the fuel tanks .that pressure is controlled at a few psi above atmospheric by the vent system exemple 248 Ram air scoops on the underside of the wing.Ram air scoops on the underside of the wing.

The types of fuel tanks used on most modern transport aircraft are ?

Question 24-33 : Integral tanks cell tanks combined fuel tanks fixed built in tanks

exemple 252 Integral tanks.Integral tanks.

The pressurization of fuel tanks is maintained by ?

Question 24-34 : The fuel vent system the fuel tank drains the fuel top off unit the fuel dump system

Each tank is vented to the outside air in order to maintain atmospheric pressure within the tank air vents are designed to minimize the possibility of their stoppage by dirt and ice formation in order to permit rapid changes in internal air pressure the size of the vent is proportional to the size of the tank thus preventing the collapse of the tank in a steep dive or glide exemple 256 The fuel vent system.The fuel vent system.

On a jet aircraft fuel heaters are ?

Question 24-35 : Located on the engines installed in each tank installed only in the centre tank not necessary at all

exemple 260 Located on the engines.Located on the engines.

The automatic fuelling shut off valve ?

Question 24-36 : Stops fuelling as soon as a certain fuel level is reached inside the tank cuts off the fuel in case of engine fire stops fuelling as soon as the fuel spills into the vent line stops fuelling as soon as a certain pressure is reached

exemple 264 Stops fuelling as soon as a certain fuel level is reached inside the tank.Stops fuelling as soon as a certain fuel level is reached inside the tank.

During re fuelling the automatic shut off valves will switch off the fuel ?

Question 24-37 : The fuel has reached a predetermined volume or mass fuelling system has reached a certain pressure the surge vent tank is filled there is fire

exemple 268 The fuel has reached a predetermined volume or mass.The fuel has reached a predetermined volume or mass.

The diagram shown in annex represents a jet fuel system the fuel flow ?

Question 24-38 : After high pressure valve item 4 in the fuel control unit item 3 after high pressure pump first stage item 2 after low pressure valve item 1

Fuel rate is measured after passing through the main engine fuel shutoff valve the fuel flow rate can be read on the display unit and is also sent to the flight management system . 870 exemple 272 After high pressure valve (item 4).After high pressure valve (item 4).

The purpose of the barometric correction in a fuel controller is to ?

Question 24-39 : Maintain the correct fuel to air mass ratio when the altitude increases maintain a constant fuel flow whatever the altitude is reduce the fuel to air mass ratio when the altitude increases increase the fuel to air mass ratio when the altitude increases

The fuel control unit fcu controls the fuel flow for a given thrust setting .variations in air intake pressure p1 require that the fuel flow to the burners is changed accordingly so that a fixed r p m is maintained for a selected throttle position at all altitudes and airspeeds this is achieved by the expansion or contraction of a capsule influenced by p1 pressure which in turn modifies the fuel flow accordingly this capsule known as the barometric pressure capsule b p c is incorporated in an 'altitude sensing unit' within the f c u .the goal is not to maintain a constant fuel flow whatever the altitude is the goal is to maintain the correct fuel to air mass ratio when the altitude increases or decreases to maintain a given thrust whatever the altitude is exemple 276 Maintain the correct fuel to air mass ratio when the altitude increases.Maintain the correct fuel to air mass ratio when the altitude increases.

At reference in flight with centre tank empty and apu operating a fuel ?

Question 24-40 : Possible with 'crossfeed' open and tank 1 pumps 'off' and tank 2 pumps 'on' possible with 'crossfeed' open and tank 2 pumps 'off' impossible because there is no fuel in center tank impossible without causing the apu stop

Img871 exemple 280 Possible with 'crossfeed' open and tank 1 pumps 'off' and tank 2 pumps 'on'.Possible with 'crossfeed' open and tank 1 pumps 'off' and tank 2 pumps 'on'.

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