Question 37-1 : An aircraft with a pressurized cabin flies at fl 310 and following a malfunction of the pressure controller the outflow valve runs to the open positiongiven cab vs cabin rate of climb indication cab alt cabin pressure altitude delta p differential pressurethis will result in a ? [ Information helipad ]

Question 37-2 : The main function of an air cycle machine is to ?

Cool the bleed air.

An air cycle machine is a bootstrap system the goal of a bootstrap system is to distribute suitable air to the cabin engine bleed air is compressed passed through a heat exchanger cooled and then across an expansion turbine

Question 37-3 : The term bootstrap when used to identify a cabin air conditioning and pressurisation system refers to the ?

Cold air unit air cycle machine arrangement.

Bootstrap or turbo compressor uses a primary heat exchanger for pre cooling against the ambient air temperature the compressor section of the cooling turbine to boost pressure and temperature to provide a significant pressure drop a secondary heat exchanger which also uses outside air as a coolant to remove the unwanted temperature rises across the compressor and the expansion turbine wich extracts work from the air by driving the compressor 856the term bootstrap refers to a self sustaining process that proceeds without external help and when used to identify a cabin air conditioning and pressurisation system it refers to the whole cold air unit system

Question 37-4 : The selection of bleed air to 'on' will cause ?

A decrease in power and an increase in exhaust temperature.

Bleed air is compressed air taken from aircraft turbine engines for cabin climate control and systems such as de icing equipmentbleed air is taken from the compressed air supply before the fuel mixing and is sent to a series of coolers and filters prior to being sent to the passenger cabinwhen bleed air is extracted from an engine some power loss will result as well as an increase in exhaust gas temperature when operating bleed air powered wing heat engine or windshield anti ice systems aircraft performance and engine power settings will change a loss of performance will result there will most likely be a substantial reduction in your maximum takeoff or landing weight if anti ice is used

Question 37-5 : Assuming cabin pressure decreases the cabin rate of climb indicator should indicate ?

A rate of climb.

As we climb the cabin altitude 'climbs' to 6000ft8000ft when the aircraft altitude climbs to fl260fl410the cabin pressure is reducing from ground pressure mean 1013 hpa to less than 750 hpa in cruising flightthus while climbing cabin rate of climb is a cabin pressure decrease

Question 37-6 : Assuming cabin differential pressure has attained the required value in normal flight conditions if flight altitude is maintained ?

A constant mass air flow is permitted through the cabin.

Question 37-7 : Assume that during cruise flight with airconditioning packs on the outflow valve s would close the result would be that ?

The pressure differential would go to the maximum value.

With packs on and if the outflow valve is closed your airplane will inflate like a balloon hopefully the pressure safety relief valve will open before damage can occur to the structure 861boeing 737 main outflow valve and pressure relief valves

Question 37-8 : Cabin air for a large aeroplane during flight ?

Is temperature controlled.

Question 37-9 : The purpose of the cabin pressure controller in the automatic mode is to perform the following functions 1 control of cabin altitude2 control of cabin altitude rate of change3 limitation of differential pressure4 balancing aircraft altitude with cabin altitude5 cabin ventilation6 keeping a ?

1 2 and 3.

Question 37-10 : Cabin pressurisation is regulated by the ?

Cabin outflow valve s .

Question 37-11 : The type of refrigerant used in a vapour cycle cooling system is ?

Freon.

Question 37-12 : Whilst in level cruising flight an aeroplane with a pressurised cabin experiences a malfunction of the pressure controller if the cabin rate of climb indicator reads 200ftmin ?

Question 37-13 : At reference in a pressurized aircraft whose cabin altitude is 8000 ft a crack in a cabin window makes it necessary to reduce the differential pressure to 5 psi the flight level to be maintained in order to keep the same cabin altidue is 862 ?

Fl 230.

From the table it can be seen that the pressure at 8000 ft is 1092 psinow we've been told because of the crack in the cabin window we can maintain a pressure differential of 5 psitherefore the air outside can only be 5 psi less than that inside the cabin ie 1092 5 = 592 again from the table the altitude where we get closest to 592 is approximately 23000 ft fl230

Question 37-14 : The pressurisation system of an aeroplane ?

Question 37-15 : In a turbo compressor air conditioning system bootstrap system the supply of air behind the primary heat exchanger is ?

Compressed passed through a heat exchanger and then across an expansion turbine.

The term bootstrap refers to a self sustaining process that proceeds without external help

Question 37-16 : The purpose of cabin air flow control valves in a pressurization system is to ?

Maintain a constant and sufficient mass air flow to ventilate the cabin and minimise cabin pressure surges.

Cabin pressurization is controlled during all phases of airplane operation by the cabin pressure control systemthe system uses bleed air supplied to and distributed by the air conditioningsystem 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 aircirculated 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 91 psi a negative relief valve prevents external atmospheric pressure from exceeding internal cabin pressure

Question 37-17 : If the pressure in the cabin tends to become lower than the outside ambient air pressure the ?

Negative pressure relief valve will open.

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 cabinambient differential try to go negativeaircraft 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

Question 37-18 : Cabin air for cs 25 aeroplanes is usually taken from ?

The high pressure compressor and from the low pressure compressor if necessary.

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

Question 37-19 : Under normal flight conditions cabin pressure is controlled by ?

Regulating the discharge of air through the outflow valve s .

Question 37-20 : Pneumatic mechanical ice protection systems are mainly used for ?

Wings.

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 863when activated rubber boots are pressurized with air and they expand breaking ice off the leading edge surfaces 864

Question 37-21 : With regard to pneumatic mechanical devices that afford ice protection the only correct statement is ?

They can only be used as de icing devices.

Question 37-22 : Concerning electrically powered ice protection devices the only true statement is ?

On modern aircraft electrically powered thermal devices are used to prevent icing on small surfaces pitot static windshield .

Question 37-23 : The elements specifically protected against icing on transport aircraft are 1 engine air intake and pod2 front glass shield3 radome4 pitot tubes and waste water exhaust masts5 leading edge of wing6 cabin windows7 trailing edge of wings8 electronic equipment compartmentthe combination ?

1 2 4 and 5.

Question 37-24 : The wing anti ice system has to protect ?

The leading edge or the slats either partially or completely.

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor 865the 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

Question 37-25 : In jet aeroplanes the 'thermal anti ice system' is primarily supplied by ?

Bleed air from the engines.

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor 865the 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

Question 37-26 : The de icing system which is mostly used for the wings of modern turboprop aeroplanes is ?

Pneumatic boots.

Question 37-27 : Concerning the sequential pneumatic impulses used in certain leading edge de icing devices one can affirm that 1 they prevent ice formation2 they are triggered from the flight deck after icing has become visible3 a cycle lasts more than ten seconds4 there are more than ten cycles per secondthe ?

Question 37-28 : Generally for large aeroplanes electrical heating for ice protection is used on ?

Pitot tubes.

Question 37-29 : The wing ice protection system currently used for most large jet transport aeroplanes is a ?

Question 37-30 : Pneumatic mechanical devices that provide ice protection ?

Are usually used as de icing devices.

Question 37-31 : The anti icing method for the wings of large jet transport aeroplanes most commonly used in flight is ?

Thermal use of hot air .

In large jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor 865the 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

Question 37-32 : Windshield heating of a transport aeroplane is ?

Essential to improve the strength of the cockpit windows.

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

Question 37-33 : The heat for the anti icing system of a turbofan engine intake is provided by ?

Bleed air from the hp compressor.

In jet aeroplanes the thermal anti ice system is primarily supplied by bleed air from the engines bleed air from the hp compressor 865the 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

Question 37-34 : The use of a hot air wing anti icing system ?

Does not affect 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 865the 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 stabilisersince 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

Question 37-35 : Ice formation on turbofan engine intakes is usually ?

Prevented by using compressor bleed air.

Question 37-36 : The ice protection for propellers of modern turboprop aeroplanes works ?

Electrically.

Ice formation on a propeller blade produces distortion to the aerofoil section causing a loss in efficiency possible unbalance and destructive vibrationthe build up of ice must be prevented and there are two systems in useprotection 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 4272 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 867cessna 208 caravan

Question 37-37 : The heating facility for the windshield of an aircraft is ?

Used on a continual basis as it reduces the thermal gradients which adversely affect the useful life of the components.

Howarthson the window heating system is selected permanently on but the heating elements are actually cycled onoff to maintain a constant temperature of the windowby keeping the window warm not only keeps it clear of ice but increases its resistance to impact damage

Question 37-38 : The wing ice protection system currently used for most large turboprop transport aeroplanes is ?

A pneumatic system with inflatable boots.

On most turboprops this is a de icing system inflatable boots 864

Question 37-39 : Electrically powered ice protection devices on aircraft are ?

Used as anti icing devices for pitot tubes static ports and windshield.

Question 37-40 : On most transport aircraft the low pressure pumps of the fuel system are ?

Centrifugal pumps driven by an electric motor.

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