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One of the purposes of the fuel system booster pumps to be submerged in the ? [ Aptitude Licence ]

Question 25-1 : 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

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 125 To facilitate the priming of the pumps.To facilitate the priming of the pumps.

The vapour lock is ?

Question 25-2 : 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

exemple 129 A stoppage in a fuel feeding line caused by a fuel vapour bubble.A stoppage in a fuel feeding line caused by a fuel vapour bubble.

The pressurising function of the pressurising and dump valve in a gas turbine ?

Question 25-3 : 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

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

Fuel pumps submerged in the fuel tanks of a multi engine aircraft are ?

Question 25-4 : Centrifugal low pressure type pumps high pressure variable swash plate pumps centrifugal high pressure pumps low pressure variable swash plate 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 137 Centrifugal low pressure type pumps.Centrifugal low pressure type pumps.

Which statement is correct .i the freezing point for jet a is at a lower ?

Question 25-5 : I is incorrect ii is incorrect i is correct ii is correct i is incorrect ii is correct i is correct 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 141 I is incorrect, ii is incorrect.I is incorrect, ii is incorrect.

Which statement is correct .i the freezing point for jet a is at a higher ?

Question 25-6 : I is correct ii is correct i is correct ii is incorrect i is incorrect ii is correct 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 145 I is correct, ii is correct.I is correct, ii is correct.

Which statement is correct .i the freezing point for jet a is at about the same ?

Question 25-7 : I is incorrect ii is correct i is correct ii is incorrect i is incorrect ii is incorrect 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 149 I is incorrect, ii is correct.I is incorrect, ii is correct.

The fuel oil heat exchanger ?

Question 25-8 : Cools the oil and heats the fuel cools the oil only cools both the oil and the fuel heats the fuel only

exemple 153 Cools the oil and heats the fuel.Cools the oil and heats the fuel.

Fuel for gas turbine engines is usually heated in order to ?

Question 25-9 : Prevent icing up of the lp filter improve the specific fuel consumption improve atomisation at low temperature improve thermal efficiency

exemple 157 Prevent icing-up of the lp filter.Prevent icing-up of the lp filter.

Fuel flow information for gas turbine engines is ?

Question 25-10 : 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

exemple 161 Measured in the line between the fuel control unit and the engine burners.Measured in the line between the fuel control unit and the engine burners.

Which statement is correct .i the freezing point for jet a is at a lower ?

Question 25-11 : I is incorrect ii is correct i is correct ii is incorrect i is correct ii is correct 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 .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 165 I is incorrect, ii is correct.I is incorrect, ii is correct.

Which statement is correct .i the freezing point for jet a is at a lower ?

Question 25-12 : I is incorrect ii is incorrect i is correct ii is incorrect i is incorrect ii is correct i is correct 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 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 169 I is incorrect, ii is incorrect.I is incorrect, ii is incorrect.

Which statement is correct .i the freezing point for jet a is at a higher ?

Question 25-13 : I is correct ii is incorrect i is incorrect ii is incorrect i is incorrect ii is correct i is correct 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 173 I is correct, ii is incorrect.I is correct, ii is incorrect.

Specific fuel consumption for a turbo prop engine can be expressed in kg per ?

Question 25-14 : Hour per unit of shaft power per unit of shaft power hour per nm hour per km

exemple 177 Hour per unit of shaft power.Hour per unit of shaft power.

The dc pump in the left main tank operates automatically to provide fuel to the ?

Question 25-15 : 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

What is the density of jet a 1 ?

Question 25-16 : 0 8 kg/l 0 7 kg/l 0 6 kg/l 0 9 kg/l

Density of jet a 1 at 15 °c is 0 804 kg/l exemple 185 0.8 kg/l.0.8 kg/l.

What does the expression 'usable fuel' mean ?

Question 25-17 : 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

Unusable fuel is ?

Question 25-18 : 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

exemple 193 Sometimes minimised by the incorporation of tank sump pads.Sometimes minimised by the incorporation of tank sump pads.

In order to ensure that all fuel on board is available to any engine on a multi ?

Question 25-19 : A cross feed a jet pump a tank shut off valve a booster pumps

exemple 197 A cross-feed.A cross-feed.

Which statement is true concerning the structure and possible advantage of an ?

Question 25-20 : 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

exemple 201 It is built internally using the aircraft structure, this saves weight and space.It is built internally using the aircraft structure, this saves weight and space.

Fuel dump systems are required ?

Question 25-21 : 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

exemple 205 On all transport category aircraft where the maximum take-off weight is significant higher than the maximum landing weight.On all transport category aircraft where the maximum take-off weight is significant higher than the maximum landing weight.

The ventilation system in a fuel tank ?

Question 25-22 : 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

exemple 209 Prevents low pressure or excessive overpressure in the tank.Prevents low pressure or excessive overpressure in the tank.

The fuel tanks of aircrafts must be checked for water ?

Question 25-23 : Before the first flight of the day or after a long turnaround time during refuelling before each flight immediately after every refuelling

exemple 213 Before the first flight of the day or after a long turnaround timeBefore the first flight of the day or after a long turnaround time

The functions of an lp booster pump in a gas turbine fuel system are to ?

Question 25-24 : 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

exemple 217 Avoid vapour locking and prevent cavitation of the hp fuel pump.Avoid vapour locking and prevent cavitation of the hp fuel pump.

Apu fuel can be provided by ?

Question 25-25 : 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

Cqb 15 september 2011 exemple 221 Any ac fuel pump supplying fuel to the left fuel manifold or by the left main tank dc fuel pump.Any ac fuel pump supplying fuel to the left fuel manifold or by the left main tank dc fuel pump.

The primary input signals for a hydro mechanical gas turbine engine fuel ?

Question 25-26 : N2 compressor discharge pressure compressor inlet temperature fuel shut off thrust lever angle n1 n2 bypass ratio fuel shut off thrust lever angle n2 bypass ratio epr fuel shut off thrust lever angle n2 turbine inlet temperature fuel shut off generator thrust lever angle

.fitted within the hp fuel pump is a 'hydro mechanical governor' which uses hydraulic pressure proportional to engine speed as its controlling parameter .this system uses n2 compressor discharge pressure compressor inlet temperature fuel shut off thrust lever angle as primary input signals exemple 225 N2, compressor discharge pressure, compressor inlet temperature, fuel shut-off, thrust lever angle.N2, compressor discharge pressure, compressor inlet temperature, fuel shut-off, thrust lever angle.

The primary reason for venting an engine oil tank is to ?

Question 25-27 : Prevent excessive pressure in the tank prevent overflow allow for expansion of hot oil cool the oil

exemple 229 Prevent excessive pressure in the tank.Prevent excessive pressure in the tank.

The cross feed fuel system can be used to .1 feed any engine from any fuel tank ?

Question 25-28 : 1 3 1 4 2 3 2 4

.using crossfeed an engine can draw fuel from a fuel tank located in the opposite wing .on most multi engine airplanes operation in the crossfeed mode is an emergency procedure used to extend airplane range and endurance in one engine inoperative flight there are a few models that permit crossfeed as a normal fuel balancing technique in normal operation fuel distribution adjustment exemple 233 1, 3.1, 3.

If one of the 12 cells of a lead acid battery is dead the battery ?

Question 25-29 : Is unserviceable has 1/12 less voltage but can still be used has 1/12 less capacity but can still be used has 1/12 less voltage and less capacity but can still be used

exemple 237 Is unserviceable.Is unserviceable.

When the ac generators are connected in parallel the reactive loads are ?

Question 25-30 : Energizing current frequency voltage torque of the constant speed drive csd

The energising current is the current that controls the voltage regulator so it will control the voltage to balance the reactive loads

In order to produce an alternating voltage of 400 hz the number of pairs of ?

Question 25-31 : 4 pairs 8 pairs 12 pairs 24 pairs

400 = 6000/60 x pole pairs.pole pairs = 4 exemple 245 4 pairs.4 pairs.

In an ac power generation system the constant speed drive csd .1 can be ?

Question 25-32 : 1 3 6 2 3 4 1 4 5 1 2 5

The csd unit is normally integral with the generator therefore the disconnect is between the csd and the engine gearbox not between the csd and the generator therefore it's only the csd that can be disconnected from the engine gearbox .the disconnect is there for the purpose of isolating a hydromechanical unit i e it might either be leaking oil overheating or causing the load sharing system to do oddball things .if you operate the disconnect it will dump the generator via the csd i e the rotational input from the engine gearbox is removed and resolves the oil leak/problem

An inverter is a ?

Question 25-33 : Unit used to convert dc into ac device for reversing the polarity of the static charge static discharger filter against radio interference

exemple 253 Unit used to convert dc into ac.Unit used to convert dc into ac.

In an aircraft electrical system where ac generators are not paralleled mounted ?

Question 25-34 : Power supply to the faulty ac generators busbar connection of the ac generator to its distribution busbar connection of the ground power truck to its distribution busbar connection of the auxiliary power unit apu to its main busbar

In an ac electrical power system where the generators are not paralleled a split busbar system only one generator can supply a busbar at any given moment however one generator may supply two or more busbars should a generator fail then its busbar would not be powered the changeover relays allow a different generator to supply that busbar in addition to its own exemple 257 Power supply to the faulty ac generators busbar.Power supply to the faulty ac generators busbar.

Pulling the fire shutoff handle causes a number of devices to disconnect in ?

Question 25-35 : Exciter control relay and the generator breaker open generator breaker opens exciter control relay the generator breaker and the tie breaker open exciter control relay opens

A control relay is a 'magnetic switch' which can isolate a circuit so is in effect the same as a 'breaker' an 'exciter breaker' and an 'exciter control relay' are in effect the same thing .an exciter breaker exciter control relay will isolate the power to the voltage regulator .the generator breaker will isolate the generator from the bus bar .the tie breaker will isolate two different bus bars from each other or can connect two generators to the same bus bar .in most cases you will want to keep bus bars connected so that you can use all your services so you will trip the generator breaker to isolate the generator from the bus bar and the exciter breaker so you effectively shut down that generator .if you have 2 generators supplying the same single bus bar then you will trip the tie breaker to isolate generator and the generator and exciter breakers to isolate and shut down the generator exemple 261 Exciter control relay and the generator breaker open.Exciter control relay and the generator breaker open.

On the ground the auxiliary power unit apu can provide .1 electricity.2 air ?

Question 25-36 : 1 2 4 1 2 3 4 1 only 2 3 4

The primary purpose of an aircraft apu is to provide power to start the main engines turbine engines must be accelerated to a high rotational speed in order to provide sufficient air compression for self sustaining operation smaller jet engines are usually started by an electric motor while larger engines are usually started by an air turbine motor before engines are to be turned the apu is started generally by a battery once the apu is running it provides power electric or pneumatic depending on the design to start the aircraft's main engines .apus are also used to run accessories while the engines are shut down this allows the cabin to be comfortable while the passengers are boarding before the aircraft's engines are started electrical power is used to run systems for preflight checks .for information some apus are also connected to a hydraulic pump allowing crews to operate hydraulic equipment but for the learning objectives apu is not considered as a power source for hydraulic pressure exemple 265 1, 2, 4.1, 2, 4.

A thermal circuit breaker ?

Question 25-37 : Protects the system in the event of overload/overheating uses electromagnetic trip system to prevent over heating limits any overcurrent can be re engaged without any danger even if the fault remains

exemple 269 Protects the system in the event of overload/overheating.Protects the system in the event of overload/overheating.

The auxiliary power unit apu has its own ac generator that ?

Question 25-38 : Supplies the aircraft with three phase 115 200 v 400 hz ac is driven at constant speed through a constant speed drive csd in the same way as the main ac generator is excited by its generator control unit gcu as soon as the apu starts up must have the same characteristics as the main ac generator so that it can be easily coupled with the latter

exemple 273 Supplies the aircraft with three-phase 115-200 v, 400 hz ac.Supplies the aircraft with three-phase 115-200 v, 400 hz ac.

A magnetic circuit breaker is ?

Question 25-39 : A protection system that has a quick tripping response permits an overcurrent limited in time can be reset without any danger even when fault remains is a system with a slow response time

exemple 277 A protection system that has a quick tripping response.A protection system that has a quick tripping response.

The advantages of alternating current on board an aircraft are .1 simple ?

Question 25-40 : 3 4 5 6 1 2 3 4 5 6 1 2 3 5 6 1 4 6

Alternating current ac is extremely versatile and has the following advantages over direct current ac can be simply and efficiently changed from one voltage to another using a transformer ac generators are simpler in construction and lighter for the equivalent power output of a dc machine ac can be easily and efficiently changed into dc using a rectifier exemple 281 3, 4, 5, 6.3, 4, 5, 6.

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