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Powerplants > Test 2 > Flashcards

Test 2 Flashcards

1
Q

Purpose of the lubrication system

A

Supply oil to the engine at the correct
- Pressure
- Volume
- Location

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2
Q

The oil tank must…

A

hold adequate amounts of oil

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3
Q

Oil Capacity

A
  • Capacity should be sufficient to supply engine
  • Multi-engine planes require independent oil systems for each engine
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4
Q

Plumbing for lubrication system

A
  • If subjected to vibration, its made w/a synthetic hose
  • If not subjected to vibration, its made out of aluminum alloy
  • Hoses should be fire resistant
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5
Q

Temperature regulation

A
  • Oil coolers regulate the temp of the flowing oil
  • It is regulated by a thermostat valve
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6
Q

Oil pressure relief valve

A
  • Controls and limits the lubricating oil pressure
  • Prevents damage to the lubrication system
  • Ensures lubrication in case of a system failure
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7
Q

Engine Oil Filters

A

Full Flow Type
- Filters ALL contaminants in the oil
- Oil is filtered before passing through bearings
Bypass type
- Filters only about 10% of contaminants
- Oil is NOT filtered before passing through bearings
Strainer type
- A tubular screen
- Designed to collapse when clogged
Disposable Filter cartridge
- Filter canister is reused while the filter element is
replaced
Spin on filter
- Incorporates wrench pad, steel case, cellulosic paper,
and a mounting plate
- Full flow type
Cuno Oil filter
- A series of laminated plates or disks
- Contaminants are trapped on the outer diameter of
the plates
- The spacing of the plates determines the size of the
particles let through

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8
Q

Oil Pressure Gauge

A
  • Measures from no pressure to above max pressure
    - They are usually a bourdon tube type
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9
Q

Oil Temperature Gauge

A
  • Sensors are usually at the oil inlet line or on the oil filter
    housing
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10
Q

Oil Pressure pump types

A
  • Gear
  • Vane

Capacity of oil pump > than engine requires

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11
Q

Scavenge Pump

A
  • Usually used for a dry-sump lubrication system
    • > capacity than pressure pumps
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12
Q

Air scoop

A

Air scoop
- Opening facing airstream
- Receives RAM air

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13
Q

Air filter

A

Air filter
- Wetted Mesh Filters
- Mat or metal filaments dipped in oil so it catches
particles
- Dry paper filters
- Air passes through a pleated layer of paper elements
- Replaced on a time-in-service basis
- Polyurethane foam filters
- Polyurethane foam and a wetting agent
- Newer type of air filter

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14
Q

Alternate air valve

A

Alternate air valve
- Allows air to flow to the engine if the air filter is clogged
- Can be manually controlled
- Is unfiltered air

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15
Q

Carburetor Heat Valve

A
  • Valve closes main air duct and opens duct to the heater muff
  • The heater muff is a shroud around the exhaust
  • It helps heat the air
  • Don’t use it during high-power operations
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16
Q

Intake Manifolds

A
  • For opposed engine types
    • Individual pipes leading to each cylinder
    • Brings the fuel-air mixture to the cylinders through the pipes
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17
Q

Induction system icing

A
  • May cut off fuel-air charge or vary fuel-air ration
  • Icing is classified into three types
    • Impact Ice
    • Fuel evaporation ice
    • Throttle ice
  • Uses Bernoulli’s principle
  • Between 40-70 F is where carb ice occurs
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18
Q

Exhaust systems

A
  • Safely removes the products of combustion from the engine
  • Exhaust gases are very toxic and hot
  • Heat collected from the exhaust is employed for
    • Cabin heating
    • Carburetor anti-icing
    • Windshield defrosting
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19
Q

Poor maintenance may lead to…

A
  • Toxic gases getting into the cabin
  • Poor engine performance
  • Damage to parts/structures
  • Nacelle fire
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20
Q

Carburetion

A
  • Provides a combustible mixture of fuel and air necessary for the engine to operate
  • Carburetor plays a part in
    • Engine performance
    • Engine mechanical life
    • General efficiency of the aircraft
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21
Q

Gasoline

A

Gasoline does not burn in liquid state, but when mixed with oxygen it becomes flammable

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22
Q

Slide 8

A

picture of carburetor

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23
Q

Fuel pump

A

takes fuel from fuel tank and brings it to the carburetor

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24
Q

Fuel Strainer

A

strains fuel of any unwanted components

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25
Q

Float chamber

A

Holds liquid fuel

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26
Q

Fuel metering needle

A

Helps control amount of fuel in chamber
- Like a toilet

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27
Q

Main metering system

A

Controls the fuel feed in the upper half of the engine

3 Units:
- Main metering jet
- Main discharge nozzle
- Passage leading to idling system

3 functions:
- Proportion the A/F mixture
- Decreases the pressure at the discharge nozzle
- Control the airflow at full throttle

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28
Q

Idling System

A
  • At idling, the airflow through the venturi is too low to draw
    sufficient fuel from the discharge nozzle
  • In order to keep the engine operating at idle speed, an idling
    system w/ an outlet at the throttle valve is added
  • Delivers fuel only when the throttle valve is nearly closed
  • Needle valve type adjustment is provided to set idle fuel flow to
    the correct air-fuel ratio
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29
Q

Carb Icing

A

If the up draft air is moisture laden, then it can freeze because as the air pressure decreases, the temp can decrease and create ice

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30
Q

Carb heat is not a preventative measure

A

If using carb heat the entire time, the engine will run worse

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31
Q

What are you doing when you move the throttle?

A

You control the amount of air that goes into the induction system

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32
Q

Acceleration System

A
  • Airflow suddenly increases when the throttle is suddenly pushed
  • Fuel flow does not accelerate proportional to the airflow increase
  • Fuel lags behind and may cause the engine to run lean which
    could cause it to stop working
  • The acceleration system discharges extra fuel into the carburetor
    when the throttle is suddenly opened
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33
Q

How do you engage the acceleration system?

A

You engage the acceleration system by pushing the throttle fully forward

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34
Q

Economizer (AKA power enrichment system)

A
  • A valve that is closed at the low engine and a cruising speed
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35
Q

Mixture Control System

A
  • Prevents mixture from becoming too rich at high altitudes
  • Economize on fuel during engine operation in the low power
    range
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36
Q

Idle Cutoff

A
  • Stops the flow of fuel from the discharge nozzle
  • Used to stop the engine
  • Engine ignition switch is turned off after the engine is first
    stopped by means of moving the mixture control to the idle
    cutoff position
  • Ensures all fuel in cylinders is used
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37
Q

Disadvantage of Float Carburetors

A
  • The fuel flow disturbances in aircraft maneuvers may interfere
    with the functions of the float mechanism
38
Q

Fuel Injected Carburetor

A
  • Discharges fuel into the airstream at or near the carburetor (throttle body)
39
Q

Fuel Injection System

A
  • Discharges fuel into the intake port of each cylinder
40
Q

Advantages of Fuel Injection System

A
  • Freedom from carb icing
  • More uniform delivery of fuel-air mixture to each cylinder
  • Improved control of fuel-air ration
  • Instant accel. after idling
  • Increased engine fuel efficiency and power
41
Q

Carburetor vs Fuel Injected

A

Carburetor - fuel meets air in the throat/carburetor
Fuel Injected - fuel is mixed immediately before entering the cylinders or in the cylinder

42
Q

Bendix (servo)

A

The heart of a fuel injection system
- Designed to meter fuel in direct ratio to the volume of air being
consumed

43
Q

Carburetor vs Servo

A
  • Carburetors is a mixing device
  • A servo is a metering device
44
Q

What are the air and fuel separated by in the servo?

A

2 diaphragms

45
Q

Impact tubes

A
  • Hangs out into the airstream
  • It fills w/ air (looks like a straw) and pushes against the air diaphragm
46
Q

Unmetered vs Metered

A
  • Coming into the servo is unmetered fuel pressure
  • Coming out of the servo is metered fuel pressure
47
Q

Metered

A

fuel measured to correct ratio

48
Q

Idle valve

A
  • At idle, low airflow is not sufficient to accurately control the fuel
    flow
  • Idle valve meters fuel accurately at idle speed
  • Is externally adjusted
  • Adjusts where ball-valve returns too
49
Q

Manual Mixture Control

A
  • Used by a pilot to reduce the metering size
    • Can lean or enrich fuel
  • Allows for shutting off fuel of fuel flow to the engine at the engine shutdown
50
Q

Manual Mixture Control

A
  • Used by pilot to reduce metering size
51
Q

Flow dividers

A
  • These are either a single-four way fitting or a tee that divides the flow into two paths
  • 2 primary functions
    • Ensures equal distribution of metered fuel to the nozzles
    • Provide isolation of each nozzle for clean engine shutdown
52
Q

Fuel Nozzles

A
  • Nozzles are of air-bleed type
  • Fuel is discharged inside the nozzle body into a chamber
53
Q

Spark Plugs

A
  • Produces a spark so that it can ignite the fuel air mixture
  • Has three parts
    • The electrodes
      - Has a positive and negative so spark jumps between
    • Ceramic Insulator
      - Inside to shield electrodes from outer shell
    • Outer shell
      - How the spark plug connects to other things
      - Prevents electrical interference
54
Q

Resistor-Type Spark Plugs

A
  • Designed to reduce the burning and erosion of electrodes in engines having shielded harness
  • Energy it can discharge is considerably greater than necessary to ignite fuel air mixture
  • It can prolong a spark plug life
55
Q

Massive Electrode Type

A
  • Electrodes consist of a copper core
56
Q

Unshielded spark plugs

A

Used in light aircrafts

57
Q

Fine wire type

A
  • similar construction to massive electrode type
  • Electrodes are made of platinum and iridium
  • Plat. and Irid. ensure max conductivity and min wear
58
Q

4 ways to sort Spark Plugs

A
  • Shielded vs Unshielded
  • Resistor vs no resistor
  • Fine wires vs massive
  • Spark plug reach (distance from shell gasket seat to end of shell threads)
59
Q

How many spark plugs do we have in a cylinder?

A

Two. One on bottom and one on top

60
Q

Heat rating Range of spark plugs

A

26-50 - indicates coldest to hottest heat range

#76-99 - indicates special application aviation plugs

61
Q

Gap and Electrode Style

A

E = two prong
N = four prong
P = Platinum fine wire
B = Two prong massive
R = Push wire

62
Q

Magneto Ignition

A
  • Superior to battery ignition
  • Produces a hotter spark at high engine speeds
  • Self-contained unit
  • Not dependent on any external source of electrical energy
63
Q

Magneto Classification

A
  • Low tension magnetos
  • High tension magnetos (most common)
  • Rotating magnet magnetos (most common)
  • Inductor rotor magnetos
  • Single magnetos
  • Double magnetos (usually bad bc there is only one shaft)
  • Flange mounted magnetos
  • Base mounted magnetos (majority of modern magnetos)
64
Q

What happens when you turn magnetos off

A

It diverts the charge through a “p” wire which grounds out the charge

65
Q

Higher the Octane…

A

The slower the fuel burns

66
Q

What does lead do to the flame front?

A

It slows the flame front which increases octane

67
Q

Fuel grades and their colors

A
  • 80/87 = Red
  • 100LL = Blue (Aviation)
  • 100/130 = Green
  • 115 = Purple
  • Jet = Clear
  • Unleaded = Clear
68
Q

*** Purpose of a Fuel system

A
  • Get clean, water-free fuel through the system
69
Q

How much fuel must a fuel system supply to the engine?

A

For gravity fed fuel tanks (high wing aircraft), they must provide 150% of the fuel needed.

For pressure fuel tanks (low wing aircraft), they must supply 125% of required fuel.

70
Q

Fuel system must also be able to shut off

A
71
Q

Vapor Lock

A
  • when an air bubble forms in the fuel line
    • Could be ice as well
    • To prevent vapor lock, make sure there aren’t any sharp bends in the
      piping
72
Q

Fuel bladders must be filled w/ fuel to prevent shriveling or shrinking

A
73
Q

Methods for Producing Thrust

A

Aerodynamic action
- Utilizes propellers
- Lift produced along a horizontal plane
- Large mass of air through small change in velocity

Jet reaction
- Mass of air heated inside the engine
- Jot air is discharged at high velocities through a shaped nozzle
- Mass of air and amount of air accelerated determines thrust
- Small mass of air w/ large change in velocity

74
Q

Brayton Cycle

A
  • Same events, but different locations
    • Intake, compression, combustion, exhaust
  • Events all happen continuously but at different places
75
Q

Similarities and differences between the Brayton and Otto cycle

A

Similarity - have the same cycles
Differences:
- Otto - all events happen in the same place and are one after another
- Entire cylinder is built for every stroke
- Brayton - events all happen in different places and are continuous
- Back is built for flame and front is not

76
Q

Convergent Duct (subsonic airflow)
______
————–
————–
______

A

Velocity increases, pressure decreases, temp decreases

77
Q

Divergent Duct (subsonic airflow)
_______
———-
———-
_______

A

Velocity decreases, pressure increases, temp increases

78
Q

What does a compressor do

A

It increases air velocity not pressure

79
Q

Divergent vs Convergent (supersonic airflow)

A

Essentially the roles switch

Convergent - velocity decreases, pressure and density increase

Divergent - velocity increases, pressure and density decrease

80
Q

Combustion in turbine engines

A
  • needs to happen at subsonic speeds
    • air flows through a chocked nozzle to slow to subsonic speeds then combustion happens and it speeds up again and exits the system.
81
Q

Type of turbine engines

A

Non-Air breathing engines (rockets)
- Carry all the needed oxygen within their fuel
- Generates heat by chemical reaction

Airbreathing reaction engines
- Turbojet
- Turboprop
- Turboshaft
- Turbofan
- Pulsejet
- Ramjet

82
Q

Turbojet engines

A
  • Takes air through air inlet
  • Compresses air
  • Mixed compressed air with fuel
  • Air forced out through specially shaped nozzle

Has a cold and hot section
- Intake and compression happen in cold section
- Combustion and exhaust happen in hot section

All the air that is brought in is compressed and exhausted`

83
Q

Turboprop

A
  • Drives a propeller
  • Two methods to drive a propeller
    • Connecting prop to the compressor
    • Connecting prop to a turbine separated from the core engine
84
Q

Turboshaft

A
  • Commonly used for helicopters
  • More efficient at a constant rpm
  • Most drives output shaft with multistage free turbine
  • Reduction gearbox is remote from the engine
85
Q

Turbofan (bypass)

A
  • Increased propulsive efficiency
  • Lower noise
  • Lower fuel consumption

3 types:
- Low bypass = 2:1 air bypassed to air used
- High bypass = 4:1 air bypassed to air used
- Ultra high bypass = 30:1 air bypassed to air used

  • More bypass air => quieter, more fuel efficient
  • Fan can produce 30%-75% of the thrust
86
Q

Unducted Fan (UHB)

A
  • More similar to turboprop
  • Drives multi-plane, contra-rotating, variable pitch propellers
87
Q

Pulse Jet engines

A

Early air breathing reaction engines

Used in WWII for missles

88
Q

Ramjet

A
  • Simplest form of air breathing engines
  • Requires near supersonic speed to operate
89
Q

Thrust

A
  • Change in momentum experienced by air flowing through the engine
  • Momentum of the fluid
  • The forces caused by the difference in pressure across the exhaust nozzle multiplied by the area of the nozzle
  • Always measured in pounds
90
Q

Two Types of Thrust

A

Net Thrust
- Thrust produced by the engine while in flight
Gross Thrust
- Thrust produced by the engine while static and not moving

91
Q

Thrust Indication

A

Smaller Jet engines
- Compressor speed in % RPM
Larger Engines
- Engine Pressure Ratio (EPR)
- Ratio of the turbine discharge total pressure to the compressor inlet
total pressure

92
Q

Ways to increase thrust

A

Afterburners
- Fuel is sprayed into hot exhaust gases which adds extra combustion
and produces more thrust

Powerplants (3 decks)

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