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ATPL - [Mod 2] AGK - Engines > 04. Piston Engine: Fuel Systems > Flashcards

04. Piston Engine: Fuel Systems Flashcards

1
Q

3 qualities that piston engine fuel must contain
1. Contain significant quantity of ____
2. Be able to form ____
3. ____ but controllably

A
  1. Energy
  2. Vapour
  3. Burn quickly

Pg 81

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2
Q

At ____℃ AVGAS has a density of ____ kg per litre

A
  1. 15℃
  2. 0.72

Pg 81

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3
Q

What is vapour lock

A

Partial or complete interruption of fuel flow due to AVGAS turning into vapour in the fuel feed

Pg 81

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4
Q

What is the term used when the AVGAS turns into a gaseous state preventing fuel flow

A

VAPOUR LOCK

Pg 81

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5
Q

The term used to explain the rapid spontanous combustion of mixture

A

DETONATION

Pg 82

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6
Q

What noise can be heard if detonation is occurring

A

ENGINE KNOCKING

Pg 82

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7
Q

What are 4 consequences of detonation

A
  1. REDUCED POWER output
  2. CYLINDER TEMPERATURE rises rapidly
  3. HOTSPOTS - due to uneven temperature
  4. PHYSICAL DAMAGE (due to hotspots)

Pg 82

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8
Q

What are 4 causes of detonation

A
  1. FUEL - Fuel with poor anti knock
  2. MIXTURE - Incorrect mixture ratio
  3. PRESSURE - Anything that raises temperature or pressure of mixture
  4. TEMPERATURE - High engine temperature

Pg 83

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9
Q

What do the following 4 traits cause
1. Fuel with poor anti knock
2. Incorrect mixture ratio
3. Anything that raises temperature or pressure of mixture
4. High engine temperature

A

DETONATION

Pg 83

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10
Q

Whare are the 4 following traits consequences of;
1. Reduced power output
2. Cylinder temperature rises rapidly
3. Hotspots - due to uneven temperature
4. Physical damage (due to hotspots)

A

DETONATION

Pg 82

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11
Q

What is the defintion of pre-ignition

A

Ignition of mixture before spark plug fires

Pg 83

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12
Q

What is a cause of pre-ignition within the cylinder

A

LOCAL HOTPOST

Local hotspots caused by carbon deposits
Likely to happen when cylinder is excessively hot or contaminated with carbon deposits

Pg 83

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13
Q
  1. Local hotspots in the cylinder are likely to cause what?
  2. They are typically as a result of what?
A
  1. Pre-ignition
  2. Carbon Deposits

Pg 83

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14
Q

The primary cause of pre-ignition

A

WEAK MIXTURE

Pg 83

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15
Q

The 3 key symptoms of pre-ignition

Think PRE-ignition

A
  1. POWER - Loss of power
  2. ROUGH RUNNING
  3. ENGINE - Overheating

Pg 83

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16
Q

Pre-ignition worsens with INCREASED or DECREASED RPM

A

INCREASED

Pg 83

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17
Q

Detonation reduces with INCREASED or DECREASED RPM

A

DECREASED

Pg 83

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18
Q

What is running-on

A

Engine continues to run a short period after shut down

Pg 83

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19
Q

If the engine continues to run after shut down, what is this known as, and what is it a characteristic of

A
  1. Running-on
  2. Pre-ignition

Pg 83

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20
Q

What is an octane rating

A

Indicates fuels resistance to detonation
AKA anti-knock value

Pg 85

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21
Q

The HIGHER or LOWER the octane rating, the HIGHER or LOWER the resistance to detonation

A
  1. HIGHER
  2. HIGHER

Pg 85

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22
Q

What additive is used to control detonation

A

TETRA-ETHYL LEAD

Pg 85

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23
Q

What colour is 100LL fuel

A

BLUE

Pg 85

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24
Q

What colour is 100 fuel

A

GREEN

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25
Q

What are 3 things that can increase the likliehood of detonation

American C O P’s can detonate

A
  1. CARB HEAT - at high power settings
  2. OVERHEATED - Overheated cylinders
  3. POWER - High power, low RPM

Pg 86

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26
Q

If the fuel with the anti-knock rating you require isnt available, you may temporarily use a fuel with HIGHER or LOWER anti-knock properties

A

HIGHER

Pg 86

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27
Q

What is the ratio of air to fuel that ensures complete combustion

A

15:1

Pg 86

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28
Q

The ratio if 15:1 is of what to what

A

AIR to FUEL

Pg 86

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29
Q

The air to fuel ratio of 15:1 is typically referred to by which 3 names

A
  1. Stoichiometric mixture
  2. Chemically correct
  3. Ideal ratio

Pg 86

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30
Q
  1. A mixture of 8:1 is RICH or LEAN
  2. A mixture of 20:1 is RICH or LEAN
A
  1. Rich
  2. Lean

Pg 86

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31
Q
  1. What is the ratio of a rich mixture
  2. What is the ratio of a lean mixture
A
  1. 8:1
  2. 20:1

Pg 86

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32
Q

The risk of detonation increases under what power setting conditions

A

HIGH POWER

Pg 87

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33
Q

High power settings INCREASE or DECREASE the risk of detonation

A

INCREASE

Pg 87

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34
Q

What is the function of having an excessively rich mixture

A

COOLING

Extra fuel not burned off, liquid aids cooling

Pg 87

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35
Q

What does excessively rich mixture cause in the exhaust gases

A

BLACK SMOKE

Pg 87

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36
Q
  1. What effect does weaker mixture have on the temperature of burning gas?
  2. What effect does this have on the engine temperature
A
  1. Cooler burning temperature
  2. Higher engine temperature

Pg 87

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37
Q

A weaker burning mixture will increase the temperature of the ____ and reduce the temperature of the ____

A
  1. Cylinder head
  2. Exhaust gas

Pg 88

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38
Q

What is the combined advantage and disadvantage of using a weak mixture in terms of efficiency

A
  1. Disadvantage - Reduced power
  2. Advantage - Reduced fuel consumption

Pg 88

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39
Q

What is a result of prolonged ground running at idle with a rich mixture

A

SPARK PLUG FOULING

Pg 88

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40
Q

What is spark plug fouling a result of

A

RICH MIXTURE when RUNNING IDLE

Pg 88

41
Q

What component is used to measure EGT or cylinder head temperature

EGT - Exhaust Gas Temperature

A

THERMOCOUPLES

Pg 89

42
Q

The highest combustion temperature occurs at what mixture ratio

A

STOICHIOMETRIC
15:1

Pg 89

43
Q

Peak EGT occurs when the mixture is what ratio

A

STOICHIOMETRIC
15:1

44
Q

How can you achieve power cruise mixture setting

A

LEAN MIXTURE to achieve peak EGT
Slowly ENRICH until EGT drops slightly

Ideal power cruis mixture ratio 12:1

Pg 89

45
Q

What is the ideal power cruise mixture ratio

A

12:1

Pg 89

46
Q

How can you achieve economy cruise mixture setting

A

LEAN MIXTURE to achieve peak EGT
Slowly LEAN mixture until EGT drops slightly

Ideal economy cruis mixture ratio 17:1

Pg 90

47
Q

What is the ideal economy cruise mixture ratio

A

17:1

Pg 90

48
Q

How does the pilot control the amount of air delivered to the engine

A

THROTTLE

Pg 91

49
Q

What does the throttle control the delivery of to the engine

A

AIR

Pg 91

50
Q

What does EDP stand for

A

ENGINE DRIVEN PUMP

Pg 92

51
Q

How is the amount of fuel in a float chamber regulated

A

By a FLOAT

Pg 92

52
Q

What is the purpose of the float

A

Regulates amount of fuel in the float chamber

Pg 92

53
Q

What is the purpose of an EDP

EDP - Engine Driven Pump

A

Ensures postive supply of fuel under pressure to the carburettor

Pg 92

54
Q

what causes fuel to be drawn up the U-tube into the throat

A

VENTURI EFFECT

The throat is a venturi
When engine is running, air is drawn into the throat
As a result of the venturi effect, pressure drops, causing fuel to be drawn into the throat

Pg 93

55
Q

What is the purpose of the fuel nozzle in a basic float carburettor

A

ATOMISE FUEL

As fuel is drawn into the throat, the nozzle will finely atomise the fuel

Pg 93

56
Q

What is the purpose of the pressure balance in a basic float carburettor

A

MAINTAIN CORRECT MIXTURE RATIO

Across a range of airspeeds and flight conditions

Maintain correct mixture ratio across range of airspeeds and flight conditions
Connects the intake and the float chamber
At high speeds, ram air effect would force air into the throat, increasing the pressure which reduces the fuel flow through the nozzle.
Similarly, higher altitudes have reduced air density, meaning less pressure in the throat, resulting in excessive fuel mixture.
The pressure balance mantains the mixture ratio

Pg 95

57
Q

What is the name of the component used in a basic float carburettor the help reduce the fuel flow through the nozzle at higher speeds which results in excessive air mass flow through the throat of the chamber. This component also aids in the mixture by adding air into the fuel before it is atomised by the nozzle

A

DIFFUSER

Pg 96

58
Q

What is the purpose of a diffuser

A

REDUCES FUEL FLOW

Helps reduce the amount of fuel flow through the nozzle when the pressure drops excessively in the throat, which would result in excessive fuel

Pg 96

59
Q

What is the purpose of a mixture control valve in a basic float carburettor

A

COMPENSATES for effect of CHANGING AIR DENSITY

As the altitude increases, the air density decreases, which would result in less air passing through the throat
The mixture control valve helps to compensate for the change in air density pressure

Pg 97

60
Q

What colour are manual mixture controls

A

RED

Pg 98

61
Q

What is the name of the component in a basic carburettor float to provide rich mixture when the engine is idle i.e. when the butterfly is closed

A

SLOW RUNNING JET

Pg 99

62
Q

What is the purpose of a slow running jet

A

Provides rich mixture when engine idle / butterfly closed

Pg 99

63
Q

How does a pilot operate the shut-off valve

A

PULL MIXTURE REWARDS

Pg 99

64
Q

A power enrichment system is required at HIGH or LOW power settings

A

HIGH POWER

Provides addition rich micture to cool the cylinders

Pg 100

65
Q

What is the name of the system that provides additional rich mixture in a basic float carburettor to cool the cylinders

A

POWER ENRICHMENT SYSTEM

Pg 100

66
Q

What is the purpose of the accelerator pump

A

Injects a quantity of fuel directly into the venturi

This is done when the throttle is rapidly moved forward.
When this happens, air flow to engine increases instantanously, but there is a slight delay before reduced pressure in throat causes additional fuel to be injected
This can cause the engine to hestitate or stop

Pg 101

67
Q

Basic float carburettor

When a pilot rapidly moves the throttle forward, what happens to the air flow and pressure in the float.
What component is fitted to help counteract the effects

A
  1. Air flow rapidly increases
  2. Pressure drop lags
  3. Accelerator pump

This is done when the throttle is rapidly moved forward.
When this happens, air flow to engine increases instantanously, but there is a slight delay before reduced pressure in throat causes additional fuel to be injected
This can cause the engine to hestitate or stop

Pg 101

68
Q

A drop in ____ and ____ are the 2 main contributors to carburettor icing

A
  1. Pressure
  2. Temperature

Pg 102

69
Q

What is the most relevent factor to carburettor icing

A

HUMIDTY

Pg 102

70
Q

When RH is more than ____%, carburettor icing may be expected in all flight conditions

RH = Relative Humidity

A

60%

Pg 103

71
Q

Serious carburettor icing is likely in ambient temepratures between ____℃ and ____℃ with a RH of ____%

RH = Relative Humidity

A
  1. 18℃
  2. 25℃
  3. 30%

Pg 104

72
Q

What is the most dangerous condition likely to cause carburettor icing

A

CRUISE or DESCENT POWER
WARM day with MODERATE or HIGH HUMIDITY

Pg 104

73
Q

What is the risk associated with a warm day with relatively high humidity, and the pilot just started a descent

A

CARBURETTOR ICING

Pg 104

74
Q

What are the 6 symptoms of carburettor icing

The Man Roughly Jammed the Exhaust in a Resolute Performance

A
  1. Manifold Pressure
  2. Rough Running
  3. Jammed Throttle
  4. Exhaust temperature drop
  5. RPM
  6. Performance (Reduced)

Loss of RPM
Reduced Performance
Reduced inlet manifold pressure
Decreased exhaust gas temperature
Rough running
Jammed throttle

Pg 105

75
Q

What is the likely first sign of carb icing on a fixed pitch propeller engine

A

REDUCED RPM

Pg 105

76
Q

What is the likely first sign of carb icing on a variable pitch propeller engine

A

REDUCED MANIFOLD PRESSURE
RPM initially remains the same

Pg 105

77
Q

How does carb heating work

A

Pilot manually selects carb heating
Hot air drawn from heat exchanger

Pg 106

78
Q

What are the 2 benefits of selecting carb heating

A
  1. Alternative source of air
  2. Prevents/removes icing

Pg 106

79
Q

What are 5 key disadvantages of using carb heating

REMEMBER: Carb Power bReaks Ice, Detonators Explode

P bR I D E - Be proud to use carb heat

A
  1. POWER (Reduced)
  2. BREAKING ICE (Reduces power)
  3. INDUCED ICING (Temperature increase to a point ideal for icing to occur)
  4. DETONATION
  5. ENRICHED MIXTURE

Reduces engine power
Induced icing. Cold ambient temperature, adding hot air may raise the air to the ideal temperature for icing to occur
Drop in power where ice breaks off and is ingested into the engine
Heated air at high power can cause detonation
Hot air is less dense, which enriches the mixture for the same power setting

Pg 107

80
Q

What is the purpose of an air induction system

A

Introduce mixture into each cylinder

Pg 108

81
Q

On a fuel injected engine when the alternative air source is selected, the RPM WILL or WILL NOT show a drop

A

WILL NOT DROP

Alternative air supply is NOT heated

Pg 110

82
Q

What is induction icing

A

ICING on AIR INTAKES

Pg 111

83
Q

What are 3 key advantages of a fuel injection system

Think Fuel Injection System

A
  1. FUEL - Reliable fuel delivery
  2. ICING - Better icing protection
  3. SPEED - Quicker throttle response

Pg 113

84
Q

How does a fuel injection system differ significantly to a carburettor system

A

NO VENTURI

Fuel delivered to engine under pressure

As fuel is delivered to the engine under pressure, there is no need for a venturi, which is how a carubruettor engine achieves fuel distribution into the throat

Pg 113

85
Q

What are 5 core components of a continuous-flow injection system

Fuel injection

REMEMBER: The Man has 2 Pumps to Inject Fuel

A
  1. MANIFOLD valve
  2. PUMP - EDP - Engine Driven Pump
  3. PUMP - Electric Pump
  4. INJECTOR assembly
  5. FUEL nozzles

EDP - Engine Driven Pump - Supplies fuel under pressure
Electric pump - Supplies fuel to injector assembly
Injector Assembly - Adjust fuel flow according to throttle and mixture positions
Manifold valve - distributes fuel from injector assembly to fuel nozzles
Fuel Nozzles - spray atomised fuel into inlets of cylinders

Pg 114

86
Q

In a continuous-flow injection system, what are the 2 functions of the electric pump

THINK…
continuous-flow - keep going if something fails
injection - What component is like a syringe

A
  1. Provide pressure if EDP fails
  2. Prime engine before start

Pg 114

87
Q

In a continuous-flow injection system, what is the metering valve connected to

THINK what are the pronounced syllables in each word..
meTering - think.. T…ta..ta
vAlve - think A..ah..ah
T A

A

THROTTLE ASSEMBLY

When the throttle lever is moved towards full power, the throttle butterfly opens, so does the metering valve
This allows more fuel flow

Pg 116

88
Q

In a continuous-flow injection system, what are the 2 core functions of the manifold valve

A
  1. Divide fuel between all cylinders
  2. Provide means of stopping fuel flow

When the mixture control is set to idle cut off, manifold valve provides a means to stopping fuel flow

Pg 116

89
Q

Large engine and diesel engines use ____ to deliver fuel to the cylinders

A

DIRECT FUEL INJECTION

Pg 117

90
Q

What does FADEC stand for

A

FULL AUTHORITY DIGITAL ENGINE CONTROL

FADEC

Pg 118

91
Q

How is a carburettor engine primed on start up

A

PLUNGER

Pg 118

92
Q

How is an injector system primed on start up

A

BOOSTER PUMP SWITCHED ON

Fuel automatically supplied when the booster pump is switched on

Pg 118

93
Q

Detonation is controlled by adding ____ to fuel

A

LEAD

Summary

94
Q

The pressure balance duct prevents ____ mixture

A

EXCESSIVELY WEAK

Summary

95
Q

The diffuser prevents ____ mixture

A

EXCESSIVELY RICH

Summary

96
Q

Petrol engines produced more CARBON MONOXIDE or SOOT than diesel engines

A

CARBON MONOXIDE

Produce less soot than diesel engines

Summary

97
Q

What 2 weather conditions are likely to cause induction icing

A
  1. SNOW
  2. HAIL

Summary

98
Q

Name each of the parts in the Basic Float Carburettor engine
LINK HERE

A
  1. EDP (Fuel delivered by EDP)
  2. Fuel Inlet Filter
  3. Needle Valve
  4. Float
  5. Accelerator Pump
  6. Pressure Balance Duct
  7. Throttle Butterfly
  8. Venturi (Throat)
  9. Jet/Nozzle
  10. Diffuser
  11. Slow Running Jet
  12. Economiser Control
  13. Mixture Control Valve

LINK HERE

ATPL - [Mod 2] AGK - Engines (23 decks)

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