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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

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
28 v ac. 28 v dc. 115 v dc.

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
5 to 10 psi. 3000 to 5000 psi. 300 to 500 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
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.

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 valvecontinued crossfeed can result in a progressive fuel imbalance
exemple 154: 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.

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
Prevent overpressure in the tank. prevent the fuel from flowing in the vent lines. prevent mixture of the fuel and hydraulic fluid.

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 ventpressurisation system used on the b737 it is a little misleading in that the tank ventilation and pressurisation systems are combinedthe ram air scoop on the lower surface of the leading edge delivers air at pressure to the fuel tanksthat pressure is controlled at a few psi above atmospheric by the vent system
exemple 162: 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.

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

Integral tanks.

exemple 166: Integral tanks
Cell tanks. combined fuel tanks. fixed built-in 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
The fuel tank drains. the fuel top off unit. the fuel dump system.

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

Located on the engines.

exemple 174: Located on the engines
Installed in each tank. installed only in the centre tank. not necessary at all.

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
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.

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
In the fuel control unit (item 3). after high pressure pump first stage (item 2). after low pressure valve (item 1).

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 settingvariations in air intake pressure p1 require that the fuel flow to the burners is changed accordingly so that a fixed rpm 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 bpc is incorporated in an 'altitude sensing unit' within the fcuthe 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
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.

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'
Possible with 'crossfeed' open and tank 2 pumps 'off'. impossible because there is no fuel in center tank. impossible without causing the apu stop.

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 sufficeit 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
To improve their efficiency. to shorten the fuel lines, so minimising the pressure losses. to heat the fuel upstream of the pump.

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
The exhaust gases obstructions caused by an engine overheating. the effect of the water vapour bubbles in the induction manifold caused by the condensation. the abnormal mixture enrichment caused by a greater gasoline vaporisation in the carburettor.

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
To prevent fuel leakage in the combustion chamber after engine shutdown. to prevent overpressure at the fuel nozzles. to admit oil to the fuel-oil heat exchanger preventing ice crystals blocking the fuel lines.

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
High pressure variable swash plate pumps. centrifugal high pressure pumps. low pressure variable swash plate pumps.

Question 38-20 : Which statement is correct i the freezing point for jet a is at a lower temperature than that for jet bii 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 temperatureanti 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 pumpedthe 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°ca 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
I is correct, ii is correct. i is incorrect, ii is correct. i is correct, 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 bii 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 temperatureanti 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 pumpedthe 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°ca 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
I is correct, ii is incorrect. i is incorrect, ii is correct. i is incorrect, ii is incorrect.

Question 38-22 : Which statement is correct i the freezing point for jet a is at about the same temperature as that for jet bii 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 temperatureanti 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 pumpedthe 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°ca 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
I is correct, ii is incorrect. i is incorrect, ii is incorrect. i is correct, 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
Cools the oil only. cools both the oil and the fuel. heats the fuel only.

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
Improve the specific fuel consumption. improve atomisation at low temperature. improve thermal efficiency.

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
Not used on aircraft. measured at the outlet of the high pressure fuel pump. measured in the line between the booster pump and the engine.

Question 38-26 : Which statement is correct i the freezing point for jet a is at a lower temperature than that for jet bii 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 fueljet 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 bjet 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 temperatureanti 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 pumpedthe 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°ca 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
I is correct, ii is incorrect. i is correct, ii is correct. i is incorrect, ii is incorrect.

Question 38-27 : Which statement is correct i the freezing point for jet a is at a lower temperature than that for jet bii 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 fueljet 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 temperatureanti 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 pumpedthe 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°ca 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
I is correct, ii is incorrect. i is incorrect, ii is correct. i is correct, ii is correct.

Question 38-28 : Which statement is correct i the freezing point for jet a is at a higher temperature than that for jet bii 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 fueljet 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 bjet 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 temperatureanti 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 pumpedthe 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°ca 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
I is incorrect, ii is incorrect. i is incorrect, ii is correct. i is correct, ii is correct.

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
Per unit of shaft power. hour per nm. hour per km.

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
Right main tank when crossfeed is open. center tank and right main tank when crossfeed is open. left engine.

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

08 kgl.

Density of jet a 1 at 15 °c is 0804 kgl
exemple 258: 08 kgl
0.7 kg/l. 0.6 kg/l. 0.9 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
The total fuel on board at start up. the total fuel remaining at any stage of the flight. the remaining fuel in the bottom of the tank when the pump is no longer immersed in fuel.

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
Always the same quantity irrespective of aircraft attitude or flight conditions. fuel contaminated by condensation water, removed by the drains. the amount of fuel available for use, but is not included on the fuel contents gauge.

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
A jet pump. a tank shut off valve. a booster pumps.

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
It is a separate metal container that is relatively light weight. is is constructed of rubber so it can be fitted into any free space within the aircraft. it is a separated metal container that is relatively cheap to manufacture.

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
On all transport category aircraft. on all transport category aircraft with more than 150 seats. on aircraft with a maximum take-off weight higher than 5.7 tons.

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
Can be used to drain the tanks, for daily checks. prevents fuel freezing during flight in icing conditions prevents vapour locking in the fuel lines.

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
During refuelling. before each flight. immediately after every refuelling.

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
Avoid vapour locking and increase the pressure during refuelling. increase the pressure during refuelling and prevent cavitation of the hp fuel pump. pressurise the fuel dump system and increase the pressure during refuelling.

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
The dc fuel pump. the left forward ac fuel pump. only by ac fuel pumps in the left main tank.



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