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Power Plant > Reciprocating Engine Fuel Metering > Flashcards

Reciprocating Engine Fuel Metering Flashcards

1
Q

Where the fuel in a float chamber system is stored

A

Float chamber

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2
Q

The five air/fuel mixture settings

A
  1. Full rich 2. idle-cutoff 3. lean best power 4. rich best power 5. best economy
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3
Q

In the induction manifold, as the throttle is opened, the pressure_______

A

rises

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4
Q

Primary cause of Pre-ignition

A

Hot-spot

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5
Q

The two types of carburetors

A

Float type, Pressure injection

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6
Q

Why an increase in humidity will decrease engine performance

A

Water is incombustible

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7
Q

In Afterburning in a piston engine, fire may appear in_____

A

The exhaust

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8
Q

An airbleed system is a vented passage with a small calibrated orifice which overcomes

A

Surface tension of the fuel

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9
Q

Relationship between volumetirc efficiency and humidity

A

Inversely propotional

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10
Q

Aircraft with Constant speed propellers, the _____ gauge can be used to help adjust fuel mixture

A

MAP

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11
Q

To compare an engine to the manufactures specifications, the AMT will have to perform a(an) __________

A

engine run-up

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12
Q

The system out of the 5 carburetor systems which allows the pilot to control the mixture

A

Mixture control system

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13
Q

The idling system allows fuel

A

to continue to flow to the engine with the venturi butterfly valve in the closed position

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14
Q

The name for the pilot controlled restrictor plate installed in the Venturi

A

Throttle valve/ butterfly valve

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15
Q

The air/fuel mixture that a typical piston will generate maximum power at

A

12:1

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16
Q

The system which provides the engine with the correct amount of fuel for all speeds above idle

A

Main metering system

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17
Q

The ratio of fuel displaced by the piston to the piston’s swept volume

A

Volumetric efficiency

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18
Q

The most likely condtion of an engine that continues to fire after the ignition has been shut off

A

Pre-ignition

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19
Q

In carburetors in which a single venturi is insufficient to provide an adequate pressure drop, a(an) ________ is installed

A

Boost venturi

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20
Q

The property that prevents a liquid from readily breaking apart based on molecular cohesiveness

A

surface tension

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21
Q

The two methods of fuel metering in reciprocating engines

A

Carburetion, fuel injection

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22
Q

The type of valve inside the float chamber

A

Needle valve

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23
Q

As a general rule for AVGAS, a ratio of _______ to _______ will support combustion

A

8:1 to 16:1

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24
Q

Condition in which an excessively rich fuel/air mixture causes a slow combustion and un-burned fuel leaves the cylinder and mixes with the air in the exhaust system and ignites

A

Afterfire

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25
Q

The condition in which an extremely lean fuel/air mixture burns slowly which will remain burning when the intake valve opens for the next cycle, which ignites the intake air before the intake valve closes and burns in the induction manifold

A

Backfiring

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26
Q

The theoretical perfect air/fuel mixture for a piston engine in 0:0 format

A

15:1

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27
Q

Burning of the fuel/air mixture prior to the spark plug firing

A

Pre-ignition

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28
Q

The three types of fuel injection

A

Direct, continuous-flow, electronically controlled

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29
Q

The only accurate way to measure a fuel/ air ratio

A

By weight

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30
Q

The tube that connects the float chamber to the throat of the venturi

A

U-tube

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31
Q

Detonation will cause: 4 things

A
  1. High cylnder head temperatures 2. Rough running engine 3. Higher pressure 4. Loss of power
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32
Q

The 5 sytems of a carburator

A
  1. Main metering 2. Idling 3. Mixture control 4. Accelerating 5. Economizer
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33
Q

The amount of work done by the engine compared to the amount of heat supplied to it

A

Thermal efficiency

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34
Q

All float chambers are vented to_______

A

atmosphere

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35
Q

What needs to happen to the fuel for complete and even burning

A

Atomized

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36
Q

Best economy mixture setting refers to the ratio which provides

A

The greatest amount of power for the least amount of fuel

37
Q

A decrease in air density for a given air/fuel mixture yields a _____ mixture

A

richer

38
Q

The number of pounds burned per hour to produce 1 horsepower

A

Specific fuel consumption

39
Q

The stoichiometric mixture describes

A

A mixture in which all oxygen is used during combustion

40
Q

Aircraft with fixed pitch propellers can use the ______gauge to adjust fuel mixture

A

Tachometer

41
Q

An increase in humidity _______ engine performance

A

Degrades

42
Q

A increase in air density for a given air/fuel mixture yields a _____ mixture

A

leaner

43
Q

The uncontrolled, explosive ignition of a fuel/air mixture in a cylinder

A

detonation

44
Q

The most accurate parameter for gauging/ setting fuel mixture

A

EGT

45
Q

The condition of the EGT in lean mixture condition

A

Higher

46
Q

The condition of the EGT in rich mixture

A

Cooler

47
Q

What he size of the pressure differential between the float chamber and the venturi will determine

A

The amount of fuel transferred from the float chamber to the main metering jet

48
Q

In a simple float type carburetor, the maximum amount of fuel flowing through the discharge nozzle is limited by

A

Size of the main metering jet

49
Q

The term for the 1/8” difference between the height level fuel in the float chamber and the height level of fuel at the discharge nozzle

A

Fuel metering head

50
Q

The function of the fuel metering head distance

A

The prevention of fuel leaking from the carburetor into the venturi

51
Q

The function of idle jets in a float type carburetor

A

Ensure consistent engine operation at idle speed

52
Q

The term for a system which uses sealed bellows to move a variable orifice, so that during a climb, when atmospheric pressure decreases, the bellows expand which leans the fuel/air mixture

A

AMC (automatic mixture control)

53
Q

When the throttle valve is opened rapidly, the condition of the fuel/air mixture______ due to _________

A

leans, due to fuel discharge nozzle lagging

54
Q

The typical method of preventing problem of the mixture momentarily leaning out during rapid opening of the throttle/ butterfly valve

A

Using of the accelerator pump

55
Q

Heat generated by operating at maximum power, which can be more than air cooling can dissipate, can be dissipated by power enrichment. Another term for power enrichment can be Economizer. Why

A

It also permits the pilot to use a leaner mixture at cruise

56
Q

2 cons of using a float type carburetor

A
  1. Ice formation 2. Unusual body attitudes
57
Q

the 2 types of carburetor icing

A
  1. Fuel evaporation ice 2. Throttle ice
58
Q

The first place on a piston engine aircraft (non fuel injection) to start accumulating ice during flight

A

Carburetor

59
Q

The process of fuel evaporation ice

A

Fuel vapor inside the venturi absorbs heat which drops the overall temperature

60
Q

Typical temperature range and humidity percentage which carburetor ice will start to form

A

40-50 F, 60%

61
Q

The very specific area in a (non fuel injection) piston engine where throttle icing first accumulates

A

Behind the partially closed throttle valve

62
Q

The description of a pressure balance duct in a carburetor system

A

A duct which balances pressure between the float chamber and the venturi

63
Q

The type of system, also named by anti-detonation injection system, used on piston engines with pressure injection, that produce

A

Water Injection system

64
Q

The composition of the fluid injected into a pressure injection carburetor system

A

Water and alcohol

65
Q

The term given for a fuel injection system which has the fuel directly injected into the combustion chamber

A

Direct fuel injection

66
Q

The most commonly used type of fuel injection system used on piston engines

A

Continuous-flow fuel injection system use in piston engines

67
Q

The fuel system in which fuel is delivered to the outside of the intake valves of the cylinder before being sucked into the cyilinder for combustion

A

Continuous-flow fuel injection

68
Q

The 2 types of continuous-flow fuel injection systems used in the US

A
  1. Precision Airmotive RSA 2. Teledyne Continental Motors
69
Q

The 5 components of the RSA Fuel metering system

A
  1. Venturi housing 2. Fuel metering unit 3. Fuel regulator 4. Fuel divider 5. Fuel Nozzle
70
Q

The system in a carburetor which increases fuel flow at high power settings

A

Power enrichment/ Economizer

71
Q

The 2 types of Economizers found on piston engines

A
  1. Needle type 2. Air bleed type
72
Q

Identify

A

Economizer needle

73
Q

The measure of the vacuum pressure between the throttle and the cylinders

A

MAP pressure

74
Q

The more the throttle is opened, the ________ that manifold pressure _______to atmospheric pressure.

A

closer, returns

75
Q

Desribe what is happening

A

Manifold pressure is lower because there is not a large amount mass flow into the engine

76
Q

Desribe what is happening

A

Since the throttle is being opened and there is more mass flow entering the intake, there is a greater density of fuel/air mxiture per same volume so there is an incrase in pressure

77
Q

The 3 types of mixture control in float type carburetors

A
  1. Variable Orifice
  2. Back suction
  3. Automatic mixture control (AMC)
78
Q

With the Back-suction mixture control, describe operation during idle/ cutoff position

A

The float chamber is vented to the low pressure side of the venturi to elimiate any potential pressure gradient between the float chamber and the discharge nozzle

79
Q

For idle mizture adjustment in a float carburetor, the engine should be run until the cylinder head

A

Cylinder head temperature is within normal range

80
Q

The required action in order to check the idle mixture control on a float carbureator and what to watch for (3 conditions- too lean, too rich, just right)

A

Pull mixture aft and watch tachometer

  1. RPM will increase slightly before dropping rapidly (just right)
  2. Immediate drop in RPM (Too lean)
  3. Momemtary increase of more than 50 RPM (too rich)
81
Q

Typical idle speed for float type carburetors engines

A

600- 800 RPM

82
Q

The checmical used to clean a carburetor of grease, oil and varnish from gasoline additives

A

Stoddard Solvent

83
Q

What not to use to dry carburetors with after cleaning with Stodard Solvent and why

A

Shop rags, lint can clog up metering jets

84
Q

How to float clearance between the gasket and float on some carburetors is measured

A

With the shank of a drill bit

85
Q

Most carburetor bodies are constructed out of

A

cast aluminium

86
Q

Since carburetor bodies are very soft (cast aluminium) the method for protecting any threaded openings from damage upon insertion

A

Insert the first thread, followed by application of thread lubricant to the threads

87
Q

The mechanical control stops on a carburetor should be reached before

A

The controls reach their stops in the cockpit

88
Q

The amount of control travel possible between the engine component’s stop and the cockpit stop is termed

A

Spring back

Power Plant (23 decks)

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