fuel systems

Question 1

an aviation fuel should have the following qualities:

• capable of being _______ and flow easily under all operating conditions
• enable engine _______ at all ground conditions and give satisfactory __lighting characteristics
• give _________ combustion under all conditions
• have as high a ________ value as possible
• minimum _________ effects on combustion systems or turbine blades
• minimum corrosive effects of fuel system components
• adequate ___________ for fuel system components
• reduce _____ risks to a minimum

Answer 1

an aviation fuel should have the following qualities:

• capable of being PUMPED and flow easily under all operating conditions
• enable engine STA RTING at all ground conditions and give satisfactory RElighting characteristics
• give EFFICIENT combustion under all conditions
• have as high a CALORIFIC value as possible
• minimum CORROSIVE effects on combustion systems or turbine blades
• minimum corrosive effects of fuel system components
• adequate LUBRICATION for fuel system components
• reduce FIRE risks to a minimum

Question 2

AVGAS 100LL

now only used for _____ aircraft

colour of AVGAS 100LL is ____

the fuel grade identification marking for AVGAS 100LL is a single ____ band followed by a ___ rectangle with AVGAS 100LL written in _____

Answer 2

AVGAS 100LL

now only used for LIGHT aircraft

colour of AVGAS 100LL is BLUE

the fuel grade identification marking for AVGAS 100LL is a single BLUE band followed by a RED rectangle with AVGAS 100LL written in WHITE

Question 3

AVTUR (JET A1 CONTAINING FS__)

the freezing point of jet A1 is around -__ celsius

the colour of jet A1 is _____/_________

the fuel grade identification markings for jet A1 is ___ _____ bands followed by a _____ rectangle, with jet A1 written in _____

Answer 3

AVTUR (JET A1 CONTAINING FSII)

the freezing point of jet A1 is around -47 celsius

the colour of jet A1 is CLEAR/COLOURLESS

the fuel grade identification markings for jet A1 is TWO BLACK bands followed by a BLACK rectangle, with jet A1 written in WHITE

Question 4

FUEL SYSTEM BLANKS/COVERS

non-standard blanks must ___ be used

Answer 4

FUEL SYSTEM BLANKS/COVERS

non-standard blanks must NOT be used

Question 5

FUEL SYSTEM ICING INHIBITOR

___ crystals can form in fuel tanks and pipelines at the very low temperatures encountered at ________

generally, this ice is formed from water that was ________ in the fuel when the aircraft was refuelled, but separated from the fuel as the temperature dropped

most aircraft have _______ on their main fuel tank filters to melt any ice that collects, which would otherwise reduce fuel flow

Answer 5

FUEL SYSTEM ICING INHIBITOR

ICE crystals can form in fuel tanks and pipelines at the very low temperatures encountered at ALTITUDE

generally, this ice is formed from water that was DISSOLVED in the fuel when the aircraft was refuelled, but separated from the fuel as the temperature dropped

most aircraft have HEATERS on their main fuel tank filters to melt any ice that collects, which would otherwise reduce fuel flow

Question 6

MICROBIOLOGICAL CONTAMINATION

cladosporium resinae

the spores can exist in a _______ state in kerosene fuels in most parts of the world but they will propagate when water is present and the temperature is between __ and __ celsius

the general geographical zone where the conditions are favourable to fungal growths is between latitudes of __ degrees north to __ degrees south

Answer 6

MICROBIOLOGICAL CONTAMINATION

cladosporium resinae

the spores can exist in a DORMANT state in kerosene fuels in most parts of the world but they will propagate when water is present and the temperature is between 15 and 35 celsius

the general geographical zone where the conditions are favourable to fungal growths is between latitudes of 30 degrees north to 30 degrees south

Question 7

FUEL QUALITY CONTROL

after a refuelling vehicle has been filled from a storage tank, it should be left to stand for at least __ minutes, then approximately one _______ of fuel should be drawn from the sump in order to check its quality. if ________ is found, further samples should be taken, until the result is satisfactory. _________ water in kerosene will give the fuel a cloudy appearance, and ____ water may often be readily visible, but in any case, a chemical water ________ method should be used.

Answer 7

FUEL QUALITY CONTROL

after a refuelling vehicle has been filled from a storage tank, it should be left to stand for at least 10 minutes, then approximately one GALLON of fuel should be drawn from the sump in order to check its quality. if SEDIMENT is found, further samples should be taken, until the result is satisfactory. SUSPENDED water in kerosene will give the fuel a cloudy appearance, and FREE water may often be readily visible, but in any case, a chemical water DETECTION method should be used.

Question 8

MINIMUM FUE FLOW REQUIREMENTS

it is a design requirement that the aircraft fuel system must be capable of delivering a supply in ______ of engine demand under the most _______ operating conditions. these conditions being ____ power at ___ level with an almost _____ tank

Answer 8

MINIMUM FUE FLOW REQUIREMENTS

it is a design requirement that the aircraft fuel system must be capable of delivering a supply in EXCESS of engine demand under the most ADVERSE operating conditions. these conditions being FULL power at SEA level with an almost EMPTY tank

Question 9

RIGID REMOVEABLE FUEL TANKS

the tank is usually constructed of _________ components welded together. a _____ or baffle(s) may be installed inside the tank to reduce the free movement of fuel called _____. the baffles are attached to the tank structure with ________ to allow a flow of fuel but reducing the surge action of the fuel

Answer 9

RIGID REMOVEABLE FUEL TANKS

the tank is usually constructed of ALUMINIUM components welded together. a BAFFLE or baffle(s) may be installed inside the tank to reduce the free movement of fuel called SURGE. the baffles are attached to the tank structure with APERTURES to allow a flow of fuel but reducing the surge action of the fuel

Question 10

INTEGRAL FUEL TANKS

integral fuel tanks are formed within the aircraft _______ by sealing compartments like ____ sections during manufacture. internal ________ both divide the wing into a number of tanks and also prevent ______. external or _______ pipes connect the tanks to the fuel system.

Answer 10

INTEGRAL FUEL TANKS

integral fuel tanks are formed within the aircraft STRUCTURE by sealing compartments like WING sections during manufacture. internal DIAPHRAGMS both divide the wing into a number of tanks and also prevent SURGE. external or INTERNAL pipes connect the tanks to the fuel system.

Question 11

FUEL PUMPS. ELECTRIC

these pumps are usually called _______ pumps when supplying fuel to the engines and ________ pumps when used to transfer fuel between tanks. however, both these functions are usually __________ and they can also have a jettison facility, where they then may also be called ________ pumps.

these are ___ positive displacement pumps

Answer 11

FUEL PUMPS. ELECTRIC

these pumps are usually called BOOSTER pumps when supplying fuel to the engines and TRANSFER pumps when used to transfer fuel between tanks. however, both these functions are usually COMBINED and they can also have a jettison facility, where they then may also be called JETTISON pumps.

these are NOT positive displacement pumps

Question 12

FUEL PUMPS. OPERATION

a _____ seal is fitted between the pump and the _____, therefore any leakage which does occur will be drained _________. if any fuel is seen to be dripping from this drain, the booster pump should be ________

Answer 12

FUEL PUMPS. OPERATION

a GLAND seal is fitted between the pump and the MOTOR, therefore any leakage which does occur will be drained OVERBOARD. if any fuel is seen to be dripping from this drain, the booster pump should be REPLACED

Question 13

PUMP POSITION. FULLY IMMERSED ‘WET BAY’

the centrifugal booster pump is normally attached directly to the ______ surface of the tank itself, for example, in integral fuel tanks

the pump is mounted o that it can be removed without _______ the tank, providing the pump incorporates a ‘_______ type’ chamber

this chamber can be isolated from the fuel in the tank by operating a simple _____ mechanism, then draining the small quantity of fuel left in the chamber before removing the inner pump.

the advantage of these ‘canister type’ pumps is that, if failure of the pump occurs, the down time of the aircraft is greatly ________ as the tanks do not require draining.

some fully immersed pumps fitted inside the tanks may be, by design, __________ or even triplicated in case of failure. therefore, the minimum equipment list may authorise flight with at least one ______ pump

Answer 13

PUMP POSITION. FULLY IMMERSED ‘WET BAY’

the centrifugal booster pump is normally attached directly to the LOWER surface of the tank itself, for example, in integral fuel tanks

the pump is mounted o that it can be removed without DRAINING the tank, providing the pump incorporates a ‘CANISTER type’ chamber

this chamber can be isolated from the fuel in the tank by operating a simple LEVER mechanism, then draining the small quantity of fuel left in the chamber before removing the inner pump.

the advantage of these ‘canister type’ pumps is that, if failure of the pump occurs, the down time of the aircraft is greatly REDUCED as the tanks do not require draining.

some fully immersed pumps fitted inside the tanks may be, by design, DUPLICATED or even triplicated in case of failure. therefore, the minimum equipment list may authorise flight with at least one FAILED pump

Question 14

JET PUMPS

these pumps use a supply of fuel from the ‘_______ pump’ to induce a flow of fuel through a ________ connected to a pipeline

the pipeline is ducted to the ______ areas of the fuel tank drawing this fuel towards the booster pumps

the jet pump has no moving parts relying on the motive flow from the booster pump to move the fuel within the tank preventing __________ and supplying the booster pump

Answer 14

JET PUMPS

these pumps use a supply of fuel from the ‘BOOSTER pump’ to induce a flow of fuel through a VENTURI connected to a pipeline

the pipeline is ducted to the REMOTE areas of the fuel tank drawing this fuel towards the booster pumps

the jet pump has no moving parts relying on the motive flow from the booster pump to move the fuel within the tank preventing STAGNATION and supplying the booster pump

Question 15

FUEL SYSTEM COMPONENTS. VENT SYSTEM

all fuel tanks must have provision for both ______ and _______ venting. the vent system must ensure that any large changes in pressure __________ do not build up between the fuel tank and the outside atmosphere

any large changes in pressure differential could cause serious structural _______ and fuel _____. the ideal condition is for a small ________ pressure acting on the fuel

conditions which require fuel venting are as follows:

• the inflow and outflow of ___ as the aircraft changes altitude
• the changes in fuel capacity as the aircraft is being _______ and defuelled
• the changes of fuel _______ as the fuel is being used by the engines
• the effects of ___________ changes which would cause expansion and contraction of the aircraft fuel contents (e.g. ground air temp +40 celsius, flight air temp -40 celsius)
• the allowance to discharge excess fuel to atmosphere should the __________ valve fail to close when the tank is filled

Answer 15

FUEL SYSTEM COMPONENTS. VENT SYSTEM

all fuel tanks must have provision for both INWARDS and OUTWARDS venting. the vent system must ensure that any large changes in pressure DIFFERENTIAL do not build up between the fuel tank and the outside atmosphere

any large changes in pressure differential could cause serious structural DAMAGE and fuel LEAKS. the ideal condition is for a small POSITIVE pressure acting on the fuel

conditions which require fuel venting are as follows:

• the inflow and outflow of AIR as the aircraft changes altitude
• the changes in fuel capacity as the aircraft is being REFUELLED and defuelled
• the changes of fuel CONTENTS as the fuel is being used by the engines
• the effects of TEMPERATURE changes which would cause expansion and contraction of the aircraft fuel contents (e.g. ground air temp +40 celsius, flight air temp -40 celsius)
• the allowance to discharge excess fuel to atmosphere should the REFUELLING valve fail to close when the tank is filled

Question 16

FUEL VENT SYSTEM OPERATION

each fuel tank is both inwardly and outwardly vented to relive both excess fuel/vapour into the ____/surge tank

the inward vent is ____ ended but the outward vent has a _____ valve fitted to minimise fuel ________ between tanks and into the vent/surge tank, with changes aircraft attitude.

vented fuel which collects in the vent/surge tank is usually _________ to the fuel tanks. the method by which the fuel is returned may be a continuous ‘___ pump’ operation or an __________ ‘electrically operated pump’ system

Answer 16

FUEL VENT SYSTEM OPERATION

each fuel tank is both inwardly and outwardly vented to relive both excess fuel/vapour into the VENT/surge tank

the inward vent is OEPN ended but the outward vent has a FLOAT valve fitted to minimise fuel TRANSFER between tanks and into the vent/surge tank, with changes aircraft attitude.

vented fuel which collects in the vent/surge tank is usually RETURNED to the fuel tanks. the method by which the fuel is returned may be a continuous ‘JET pump’ operation or an INTERMITTENT ‘electrically operated pump’ system

Question 17

VALVES

low _______ valves, cross ____ valves and _____ engine valves are usually ____ type, full flow valves and may be either __________ or __________ operated.

these are ___ position valves only, and either internal or external _________ stops are provided, to limit movement to __ degrees. a ______ indication of valve position is also provided.

_____ switches cut off power to the _____ at the fully open and fully closed positions, and the brake operates automatically as the motor is __-energised. the brake is ____________ released when a reverse selection is made. the limit switches may also be used to operate ________ indicator lights or magnetic indicators in the crew compartment

Answer 17

VALVES

low PRESSURE valves, cross FEED valves and INTER engine valves are usually BALL type, full flow valves and may be either MECHANICALLY or ELECTRICALLY operated.

these are TWO position valves only, and either internal or external MECHANICAL stops are provided, to limit movement to 90 degrees. a VISUAL indication of valve position is also provided.

LIMIT switches cut off power to the MOTOR at the fully open and fully closed positions, and the brake operates automatically as the motor is DE-energised. the brake is MAGNETICALLY released when a reverse selection is made. the limit switches may also be used to operate POSITION indicator lights or magnetic indicators in the crew compartment

Question 18

VALVES. LP COCKS

LP cocks are used to isolate the ________ mounted fuel system from the engine

Answer 18

VALVES. LP COCKS

LP cocks are used to isolate the AIRFRAME mounted fuel system from the engine

Question 19

VALVES. SUCTION VALVES

suction valves are fitted to permit fuel to be drawn from the tanks in the event of ________ pump failure. when the pump is operating normally, the pressure in the pipeline keeps the valve ______. if the pump fails, the suction created by the ______ driven pump will draw fuel through the suction valve thereby preventing the engine from being _______ of fuel

Answer 19

VALVES. SUCTION VALVES

suction valves are fitted to permit fuel to be drawn from the tanks in the event of BOOSTER pump failure. when the pump is operating normally, the pressure in the pipeline keeps the valve CLOSED. if the pump fails, the suction created by the ENGINE driven pump will draw fuel through the suction valve thereby preventing the engine from being STARVED of fuel

Question 20

FUEL SYSTEMS. GENERAL

a simple fuel system may consist of a ______ feed tank, a _____, a shut off _____ and suitable rigid a flexible _____ between these components and the ______

Answer 20

FUEL SYSTEMS. GENERAL

a simple fuel system may consist of a GRAVITY feed tank, a FILTER, a shut off VALVE and suitable rigid and flexible PIPES between these components and the ENGINE

Question 21

FUEL TANK COMPONENTS

each fuel tank is fitted with a ____ pipe which is vented to the outside of the ____ structure. this vent pipe ensures that _________ pressure is maintained within the fuel tank

a non-return valve (NRV) attached to the vent pipe inside the fuel tank prevents any fuel from ________ though the vent pipe. a small ____ in the NRV prevents any build up of pressure when the NRV is ______

on some light aircraft, a small amount of fuel ____ be drained off from both the ____ and main filter _____ to ensure that any concentration of _____ is removed prior to flight

Answer 21

FUEL TANK COMPONENTS

each fuel tank is fitted with a VENT pipe which is vented to the outside of the WING structure. this vent pipe ensures that ATMOSPHERIC pressure is maintained within the fuel tank

a non-return valve (NRV) attached to the vent pipe inside the fuel tank prevents any fuel from SIPHONING though the vent pipe. a small HOLE in the NRV prevents any build up of pressure when the NRV is CLOSED

on some light aircraft, a small amount of fuel MUST be drained off from both the TANK and main filter DRAINS to ensure that any concentration of WATER is removed prior to flight

Question 22

THE SELECTOR VALVE/LP COCK

the selector valve enables the engine to be fed from ________ tanks or ____ tanks together and an has an on/off position to enable the fuel supply to be turned ___

Answer 22

THE SELECTOR VALVE/LP COCK

the selector valve enables the engine to be fed from INDIVIDUAL tanks or BOTH tanks together and an has an on/off position to enable the fuel supply to be turned OFF

Question 23

BOOSTER PUMP

all fuel pumps are referred to as _______ pumps

the booster pump is ________ operated and is fitted to ensure a _______ fuel supply to the engine under all conditions such as:

• ____ting
• take ___
• clim____
• high _______
• turbu____
• lan____

all aircraft fuel systems are designed to provide adequate fuel for all engine requirements, even if the booster pump _____

Answer 23

BOOSTER PUMP

all fuel pumps are referred to as BOOSTER pumps

the booster pump is ELECTRICALLY operated and is fitted to ensure a POSITIVE fuel supply to the engine under all conditions such as:

• STARting
• take OFF
• climBING
• high ALTITUDE
• turbuLENCE
• lanDING

all aircraft fuel systems are designed to provide adequate fuel for all engine requirements, even if the booster pump FAILS

Question 24

FUEL FEED

individual engines are usually fed from an ________ tank or _____ of tanks

_____-feed and _____-engine valves are provided to enable the engines to be fed from any desired group of tanks, and also to permit fuel _______ between tanks

Answer 24

FUEL FEED

individual engines are usually fed from an ASSOCIATED tank or GROUP of tanks

CROSS-feed and INTER-engine valves are provided to enable the engines to be fed from any desired group of tanks, and also to permit fuel TRANSFER between tanks

Question 25

CASCADE DEVICE

refuelling pipes within the tanks are fitted with a cascade device, the purpose of which is to prevent _______ to the tank interior especially the _______, which would be the result if a pressurised ___ of fuel entered the tank

Answer 25

CASCADE DEVICE

refuelling pipes within the tanks are fitted with a cascade device, the purpose of which is to prevent DAMAGE to the tank interior especially the SEALANT, which would be the result if a pressurised JET of fuel entered the tank

Question 26

ENSURING CORRECT FUEL USED

always ensure correct fuel is used as follows:

• aircraft refuelling _______ and any over wing _______ point should be clearly marked with the type of fuel to be used (e.g. jet A1)
• tanker/_______ should be clearly marked with the type of fuel to be used (e.g. jet A1)
• the ____ should clearly state the type of fuel to be used

Answer 26

ENSURING CORRECT FUEL USED

always ensure correct fuel is used as follows:

• aircraft refuelling STATION and any over wing FILLING point should be clearly marked with the type of fuel to be used (e.g. jet A1)
• tanker/HYDRANT should be clearly marked with the type of fuel to be used (e.g. jet A1)
• the AMM should clearly state the type of fuel to be used

Question 27

FUELLING GENERAL OPERATION

fuelling can also be accomplished without _______ power by _________ operating the fuelling valves and using the quantity measuring ________

Answer 27

FUELLING GENERAL OPERATION

fuelling can also be accomplished without ELECTRICAL power by MANUALLY operating the fuelling valves and using the quantity measuring DRIPSTICK

Question 28

FUEL JETTISON/FUEL DUMPING

many large aircraft are equipped with a means of _________ excess fuel in an emergency. fuel is pumped from each tank through a _____ pipe, which ensures that a pre-determined ________ of fuel remains

one of the booster pumps in each tank, may be run at a ______ speed for the jettisoning operation to offload the fuel, whilst the fuel feed to the engines is protected by ___-return valves

when a jettison pipe is in the _________ position it forms a seal at the manifold, and acts as a ______ jettison valve. the jettison valves are not _____ until this pipe is locked in the ________ position. both types of systems are controlled from a special _____ at the crew station, which contains ________ for the pumps and valves, and warning _____ or magnetic __________ to show the positions of the valves and jettison pipes

Answer 28

FUEL JETTISON/FUEL DUMPING

many large aircraft are equipped with a means of JETTISONING excess fuel in an emergency. fuel is pumped from each tank through a STAND pipe, which ensures that a pre-determined QUANTITY of fuel remains

one of the booster pumps in each tank, may be run at a HIGHER speed for the jettisoning operation to offload the fuel, whilst the fuel feed to the engines is protected by NON-return valves

when a jettison pipe is in the RETRACTED position it forms a seal at the manifold, and acts as a MASTER jettison valve. the jettison valves are not ARMED until this pipe is locked in the EXTENDED position. both types of systems are controlled from a special PANEL at the crew station, which contains SWITCHES for the pumps and valves, and warning LAMPS or magnetic INDICATORS to show the positions of the valves and jettison pipes

Question 29

FUEL QUANTITY

for ___ stick and ____ stick fuel quantity measuring, the aircraft must be _________ both laterally and longitudinally to obtain accurate readings

Answer 29

FUEL QUANTITY

for DIP stick and DRIP stick fuel quantity measuring, the aircraft must be LEVELLED both laterally and longitudinally to obtain accurate readings

Question 30

FUEL HEATING

a manually controlled fuel heating system usually consists of a ________ differential switch on the fuel ______, which operates a warning ____ in the crew compartment, and an electrically operated valve on the heat _________, which is controlled by a switch ________ to the warning lamp

when fuel flow through the filter becomes restricted by ___, the differential pressure across the filter _________, until it is sufficient to operate the icing warning lamp

an automatically controlled fuel heating system consists of a _____________ controlled air inlet valve on he heat exchanger, which progressively ______ and _______ to maintain fuel outlet temperature within pre-set limits above _ celsius. actual fuel temperature is indicated on an instrument on the fuel control _____, but no action is required by the crew

Answer 30

FUEL HEATING

a manually controlled fuel heating system usually consists of a PRESSURE differential switch on the fuel FILTER, which operates a warning LAMP in the crew compartment, and an electrically operated valve on the heat EXCHANGER, which is controlled by a switch ADJACENT to the warning lamp

when fuel flow through the filter becomes restricted by ICE, the differential pressure across the filter INCREASES, until it is sufficient to operate the icing warning lamp

an automatically controlled fuel heating system consists of a THERMOSTATICALLY controlled air inlet valve on he heat exchanger, which progressively OPENS and CLOSES to maintain fuel outlet temperature within pre-set limits above 0 celsius. actual fuel temperature is indicated on an instrument on the fuel control PANEL, but no action is required by the crew

Question 31

REFUELLING

the term fuelling embraces both fuelling and defuelling

before fuelling, it should be ensured that the fuelling vehicle contains the correct _____ of fuel, as shown at the fuelling points of the aircraft

fuelling should always be carried out at a place approved by the ________ authority. it must be at least __ metres (50 feet) from any building

no smoking signs must be displayed __ less than 15 metres (__ feet) from the fuelling area

ground power units may be operated provided they are at least _ metres (20 feet) from aircraft _______ and _______ positions

precautions should be taken to provide a ____ to earth for any ______ electricity which may be present or which may build up as a result of the fuel flow. the _______ and the fuelling ________ should be earthed to a point which is known to be __________, and the earthing wire on the fuelling pipe should be connected to the earth point provided on the _______ before connecting the ________ pipe or removing the tank filler cap. the earthing wire should remain in position until _____ the the fuelling pipe is disconnected or the tank filler cap is replace, as appropriate

as stated previously, after fuelling an aircraft, the fuel must be checked for ____________ after waiting for a period of time for the fuel to settle.

however, it may be commercially practical to carry out a check _______ fuelling

Answer 31

REFUELLING

the term fuelling embraces both fuelling and defuelling

before fuelling, it should be ensured that the fuelling vehicle contains the correct GRADE of fuel, as shown at the fuelling points of the aircraft

fuelling should always be carried out at a place approved by the AERODROME authority. it must be at least 15 metres (50 feet) from any building

no smoking signs must be displayed NOT less than 15 metres (50 feet) from the fuelling area

ground power units may be operated provided they are at least 6 metres (20 feet) from aircraft VENTING and FILLING positions

precautions should be taken to provide a PATH to earth for any STATIC electricity which may be present or which may build up as a result of the fuel flow. the AIRCRAFT and the fuelling VEHICLE should be earthed to a point which is known to be SATISFACTORY, and the earthing wire on the fuelling pipe should be connected to the earth point provided on the AIRCRAFT before connecting the FUELLING pipe or removing the tank filler cap. the earthing wire should remain in position until AFTER the the fuelling pipe is disconnected or the tank filler cap is replace, as appropriate

as stated previously, after fuelling an aircraft, the fuel must be checked for CONTAMINATION after waiting for a period of time for the fuel to settle.

however, it may be commercially practical to carry out a check BEFORE fuelling