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Question 38-1 : The fuel supply system on a jet engine includes a fuel heating device upstream of the main fuel filter so as to ? [ Path visibility ]

Prevent at low fuel temperature the risk of ice formation from water contained in the fuel

exemple 138 Prevent, at low fuel temperature, the risk of ice formation from water contained in the fuel.

Question 38-2 : On most transport jet aircraft the low pressure pumps of the fuel system are supplied with electric power of the following type ?

115 v ac

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 142 115 v ac.

Question 38-3 : The pressure usually produced by the booster pumps of the fuel supply system of a large jet transport aeroplane is within the following range ?

20 to 50 psi

exemple 146 20 to 50 psi.

Question 38-4 : In a gas turbine engine lubrication system the oil to fuel heat exchanger provides ?

Oil cooling through thermal exchange with the fuel

exemple 150 Oil cooling through thermal exchange with the fuel.

Question 38-5 : The fuel cross feed system ?

Allows feeding of any engine from any fuel tank

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 154 Allows feeding of any engine from any fuel tank.

Question 38-6 : The purpose of baffles in an aeroplane's integral fuel tank is to ?

Restrict the fuel movements in the tank

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 158 Restrict the fuel movements in the tank.

Question 38-7 : On a transport type aircraft the fuel tank system is vented through ?

Ram air scoops on the underside of the wing

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 162 Ram air scoops on the underside of the wing.

Question 38-8 : The types of fuel tanks used on most modern transport aircraft are ?

Integral tanks

exemple 166 Integral tanks.

Question 38-9 : The pressurization of fuel tanks is maintained by ?

The fuel vent 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 170 The fuel vent system.

Question 38-10 : On a jet aircraft fuel heaters are ?

Located on the engines

exemple 174 Located on the engines.

Question 38-11 : The automatic fuelling shut off valve ?

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

exemple 178 Stops fuelling as soon as a certain fuel level is reached inside the tank.

Question 38-12 : During re fuelling the automatic shut off valves will switch off the fuel supply system when ?

The fuel has reached a predetermined volume or mass


Question 38-13 : The diagram shown in annex represents a jet fuel system the fuel flow measurement is carried out . 868 ?

After high pressure valve item 4

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 186 After high pressure valve (item 4).

Question 38-14 : The purpose of the barometric correction in a fuel controller is to ?

Maintain the correct 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

Question 38-15 : At reference in flight with centre tank empty and apu operating a fuel unbalance is detected quantity in tank 1 < quantity in tank 2 .rebalancing of the two tanks is . 872 ?

Possible with 'crossfeed' open and tank 1 pumps 'off' and tank 2 pumps 'on'

Img871 exemple 194 Possible with 'crossfeed' open and tank 1 pumps 'off' and tank 2 pumps 'on'.

Question 38-16 : One of the purposes of the fuel system booster pumps to be submerged in the fuel is ?

To facilitate the priming of the pumps

The pumps are cooled by the fuel and lubricated by it to achieve these functions the pumps would not need to be submerged in the fuel the action of the flow through the pumps would suffice .it is important that the pumps only pump the fuel not air to this end ensuing the pumps are submerged in the fuel will keep them primed with fuel exemple 198 To facilitate the priming of the pumps.

Question 38-17 : The vapour lock is ?

A stoppage in a fuel feeding line caused by a fuel vapour bubble

exemple 202 A stoppage in a fuel feeding line caused by a fuel vapour bubble.

Question 38-18 : The pressurising function of the pressurising and dump valve in a gas turbine engine fuel system is ?

To admit fuel to the nozzles only if the fuel pressure is high enough for sufficient atomisation

.a pressurising and dump valve is used with a duplex fuel nozzle at a preset pressure the pressurising valve opens and allows fuel to flow into the main manifold as well as the pilot or primary manifold the dump valve allows the manifold fuel to be dumped into the drains tank when the engine is shut down to prevent fuel boiling in the manifold due to residual engine heat exemple 206 To admit fuel to the nozzles only if the fuel pressure is high enough for sufficient atomisation.

Question 38-19 : Fuel pumps submerged in the fuel tanks of a multi engine aircraft are ?

Centrifugal low pressure type pumps

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 210 Centrifugal low pressure type pumps.

Question 38-20 : Which statement is correct .i the freezing point for jet a is at a lower temperature than that for jet b .ii the flash point for jet a is at a lower temperature than that for jet b ?

I is incorrect ii is incorrect

.jet b has a higher napthalene content and that helps prevent freezing gelling at low temperatures but in practice that is not a useful property of jet b see below .jet fuel is a blend of many different hydrocarbons that each have their own specific freezing point so it is not really possible to quote a freezing point temperature the 'pour point' is the term used in the aviation industry to specify the minimum safe temperature .anti ice additives such as 'prist' are used in jet a at cold temperatures so that it can still be pumped without reducing fuel flow at 70°c more than sufficient for any jet aircraft even at 10 15°c below the first component to freeze usually paraffin wax jet fuel can still be pumped .the accepted minimum fuel temperature for safe flight for jet a is 40°c jet a 1 is 47°c and jet b is 65°c . flight crews must monitor fuel temperature to ensure that the fuel does not cool to below the pour point .jet b has a flash point of below 0°c and jet a is around 38°c .a low flash point is a useful property to start a jet engine in cold weather but reduces the amount of energy stored in fuel remember that the lower the flash point the more 'volatile' the fuel is exemple 214 I is incorrect, ii is incorrect.

Question 38-21 : Which statement is correct .i the freezing point for jet a is at a higher temperature than that for jet b .ii the flash point for jet a is at a higher temperature than that for jet b ?

I is correct ii is correct

.jet b has a higher napthalene content and that helps prevent freezing gelling at low temperatures but in practice that is not a useful property of jet b see below .jet fuel is a blend of many different hydrocarbons that each have their own specific freezing point so it is not really possible to quote a freezing point temperature the 'pour point' is the term used in the aviation industry to specify the minimum safe temperature .anti ice additives such as 'prist' are used in jet a at cold temperatures so that it can still be pumped without reducing fuel flow at 70°c more than sufficient for any jet aircraft even at 10 15°c below the first component to freeze usually paraffin wax jet fuel can still be pumped .the accepted minimum fuel temperature for safe flight for jet a is 40°c jet a 1 is 47°c and jet b is 65°c . flight crews must monitor fuel temperature to ensure that the fuel does not cool to below the pour point .jet b has a flash point of below 0°c and jet a is around 38°c .a low flash point is a useful property to start a jet engine in cold weather but reduces the amount of energy stored in fuel remember that the lower the flash point the more 'volatile' the fuel is exemple 218 I is correct, ii is correct.

Question 38-22 : Which statement is correct .i the freezing point for jet a is at about the same temperature as that for jet b .ii the flash point for jet a is at a higher temperature than that for jet b ?

I is incorrect ii is correct

.jet b has a higher napthalene content and that helps prevent freezing gelling at low temperatures but in practice that is not a useful property of jet b see below .jet fuel is a blend of many different hydrocarbons that each have their own specific freezing point so it is not really possible to quote a freezing point temperature the 'pour point' is the term used in the aviation industry to specify the minimum safe temperature .anti ice additives such as 'prist' are used in jet a at cold temperatures so that it can still be pumped without reducing fuel flow at 70°c more than sufficient for any jet aircraft even at 10 15°c below the first component to freeze usually paraffin wax jet fuel can still be pumped .the accepted minimum fuel temperature for safe flight for jet a is 40°c jet a 1 is 47°c and jet b is 65°c . flight crews must monitor fuel temperature to ensure that the fuel does not cool to below the pour point .jet b has a flash point of below 0°c and jet a is around 38°c .a low flash point is a useful property to start a jet engine in cold weather but reduces the amount of energy stored in fuel remember that the lower the flash point the more 'volatile' the fuel is exemple 222 I is incorrect, ii is correct.

Question 38-23 : The fuel oil heat exchanger ?

Cools the oil and heats the fuel

exemple 226 Cools the oil and heats the fuel.

Question 38-24 : Fuel for gas turbine engines is usually heated in order to ?

Prevent icing up of the lp filter

exemple 230 Prevent icing-up of the lp filter.

Question 38-25 : Fuel flow information for gas turbine engines is ?

Measured in the line between the fuel control unit and the engine burners

exemple 234 Measured in the line between the fuel control unit and the engine burners.

Question 38-26 : Which statement is correct .i the freezing point for jet a is at a lower temperature than that for jet b .ii the flash point for jet a is at a higher temperature than that for jet b ?

I is incorrect ii is correct

Jet kerosene jet a1 or jet a jet gasoline jet b and aviation gasoline avgas are the names given for fuel .jet b has a higher napthalene content and that helps prevent freezing gelling at low temperatures but in practice that is not a useful property of jet b .jet fuel is a blend of many different hydrocarbons that each have their own specific freezing point so it is not really possible to quote a freezing point temperature the 'pour point' is the term used in the aviation industry to specify the minimum safe temperature .anti ice additives such as 'prist' are used in jet a at cold temperatures so that it can still be pumped without reducing fuel flow at 70°c more than sufficient for any jet aircraft even at 10 15°c below the first component to freeze usually paraffin wax jet fuel can still be pumped .the accepted minimum fuel temperature for safe flight for jet a is 40°c jet a 1 is 47°c and jet b is 65°c . flight crews must monitor fuel temperature to ensure that the fuel does not cool to below the pour point .jet b has a flash point of below 0°c and jet a is around 38°c .a low flash point is a useful property to start a jet engine in cold weather but reduces the amount of energy stored in fuel remember that the lower the flash point the more 'volatile' the fuel is exemple 238 I is incorrect, ii is correct.

Question 38-27 : Which statement is correct .i the freezing point for jet a is at a lower temperature than that for jet b .ii the flash point for jet a is at about the same temperature as that for jet b ?

I is incorrect ii is incorrect

Jet kerosene jet a1 or jet a jet gasoline jet b and aviation gasoline avgas are the names given for fuel .jet b has a higher napthalene content and that helps prevent freezing gelling at low temperatures but in practice that is not a useful property of jet b see below .jet fuel is a blend of many different hydrocarbons that each have their own specific freezing point so it is not really possible to quote a freezing point temperature the 'pour point' is the term used in the aviation industry to specify the minimum safe temperature .anti ice additives such as 'prist' are used in jet a at cold temperatures so that it can still be pumped without reducing fuel flow at 70°c more than sufficient for any jet aircraft even at 10 15°c below the first component to freeze usually paraffin wax jet fuel can still be pumped .the accepted minimum fuel temperature for safe flight for jet a is 40°c jet a 1 is 47°c and jet b is 65°c . flight crews must monitor fuel temperature to ensure that the fuel does not cool to below the pour point .jet b has a flash point of below 0°c and jet a is around 38°c .a low flash point is a useful property to start a jet engine in cold weather but reduces the amount of energy stored in fuel remember that the lower the flash point the more 'volatile' the fuel is

Question 38-28 : Which statement is correct .i the freezing point for jet a is at a higher temperature than that for jet b .ii the flash point for jet a is at a lower temperature than that for jet b ?

I is correct ii is incorrect

Jet kerosene jet a1 or jet a jet gasoline jet b and aviation gasoline avgas are the names given for fuel .jet b has a higher napthalene content and that helps prevent freezing gelling at low temperatures but in practice that is not a useful property of jet b .jet fuel is a blend of many different hydrocarbons that each have their own specific freezing point so it is not really possible to quote a freezing point temperature the 'pour point' is the term used in the aviation industry to specify the minimum safe temperature .anti ice additives such as 'prist' are used in jet a at cold temperatures so that it can still be pumped without reducing fuel flow at 70°c more than sufficient for any jet aircraft even at 10 15°c below the first component to freeze usually paraffin wax jet fuel can still be pumped .the accepted minimum fuel temperature for safe flight for jet a is 40°c jet a 1 is 47°c and jet b is 65°c . flight crews must monitor fuel temperature to ensure that the fuel does not cool to below the pour point .jet b has a flash point of below 0°c and jet a is around 38°c .a low flash point is a useful property to start a jet engine in cold weather but reduces the amount of energy stored in fuel remember that the lower the flash point the more 'volatile' the fuel is exemple 246 I is correct, ii is incorrect.

Question 38-29 : Specific fuel consumption for a turbo prop engine can be expressed in kg per ?

Hour per unit of shaft power

exemple 250 Hour per unit of shaft power.

Question 38-30 : The dc pump in the left main tank operates automatically to provide fuel to the . 873 ?

Apu when ac power is not available and the apu selector is on

exemple 254 Apu when ac power is not available and the apu selector is on.

Question 38-31 : What is the density of jet a 1 ?

0 8 kg/l

Density of jet a 1 at 15 °c is 0 804 kg/l exemple 258 0.8 kg/l.

Question 38-32 : What does the expression 'usable fuel' mean ?

The total amount of fuel that can be supplied to the engine

exemple 262 The total amount of fuel that can be supplied to the engine.

Question 38-33 : Unusable fuel is ?

Sometimes minimised by the incorporation of tank sump pads

exemple 266 Sometimes minimised by the incorporation of tank sump pads.

Question 38-34 : In order to ensure that all fuel on board is available to any engine on a multi engine aircraft it must be fitted with ?

A cross feed

exemple 270 A cross-feed.

Question 38-35 : Which statement is true concerning the structure and possible advantage of an integral fuel tank ?

It is built internally using the aircraft structure this saves weight and space

exemple 274 It is built internally using the aircraft structure, this saves weight and space.

Question 38-36 : Fuel dump systems are required ?

On all transport category aircraft where the maximum take off weight is significant higher than the maximum landing weight

exemple 278 On all transport category aircraft where the maximum take-off weight is significant higher than the maximum landing weight.

Question 38-37 : The ventilation system in a fuel tank ?

Prevents low pressure or excessive overpressure in the tank

exemple 282 Prevents low pressure or excessive overpressure in the tank.

Question 38-38 : The fuel tanks of aircrafts must be checked for water ?

Before the first flight of the day or after a long turnaround time

exemple 286 Before the first flight of the day or after a long turnaround time

Question 38-39 : The functions of an lp booster pump in a gas turbine fuel system are to ?

Avoid vapour locking and prevent cavitation of the hp fuel pump

exemple 290 Avoid vapour locking and prevent cavitation of the hp fuel pump.

Question 38-40 : Apu fuel can be provided by ?

Any ac fuel pump supplying fuel to the left fuel manifold or by the left main tank dc fuel pump

Cqb 15 september 2011 exemple 294 Any ac fuel pump supplying fuel to the left fuel manifold or by the left main tank dc fuel pump.


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