Exam 2 Review Flashcards
Parts of an Oil System (9)
Pressure Oil Pump
Oil Pressure Relief Valve
Oil Reservoir
Oil Pressure Gage
Oil Temperature Gage
Oil Filter
Necessary Piping and Connections
Oil Coolers
Oil Dilution Systems
Oil Pressure Relief Valve
Control and limit the lubricating oil pressure
Prevent damage to the lubrication system
Ensure lubrication in case of a system failure
Oil Filter Types (5)
Full-Flow
Bypass
Strainer
Spin-On
Cuno Oil
Full-Flow Filter
Filtering all the circulated oil of contaminants
All oil are filtered before passing through bearing surfaces
If Filter is clogged, a relief valve will open. Allowing oil bypass
Bypass Filter
Filters about 10% of the oil through filtering element and returns oil to sump
Oil passing through bearings are not filtered oil
Strainer Filter
A simple tubular screen
Designed to collapse when clogged or designed with relief valves that also open when clogged
Spin-On Filter
Newest style
Canister and filter element are one unit
Incorporates wrench pad, steel case, cellulosic paper, and mounting plate with threaded end for mounting to the engine
Full-flow type
Cuno Oil Filter
Series of laminated plates or disks
Contaminants are trapped on the outer diameter of the plates
The spacing of the plates will determine the particle size that may pass through
Alternate Air Valve Function
Allows air to flow to the engine if air filter is clogged
Carb Heat Valve Function
Operated by the carburetor heat control in the cockpit
The valve closes the main air duct and opens the duct to the heater muff
Causes of Intake Icing (3)
Flying through Clouds, Fog, Rain, Sleet, Snow, or High moisture clear air
if the temperature before the air scoop is below freezing point of water
when particles of water in the air strike cold surfaces
Exhaust System Function
Removes the products of combustion from the engine safely and effectively
Exhaust System Issues
Poor maintenance can lead to Nacelle fires, Toxic gases entering the cockpit and cabin, Damage to parts and structure in nacelle and, Poor engine performance
Characteristics of Fuel (4)
High heat value
Ability to evaporate when exposed to air
Ability to evaporate at ordinary temperatures
High volatility
Fuel Grades and Colors (4)
100 (green)
100LL (blue)
UL94 (unleaded)
UL91
Fuel System Parts (9)
Fuel Tanks
Fuel Boost Pump
Tank Strainer
Fuel Tank Vents
Fuel Lines
Fuel Control or Selector Valves
Main Strainer
Fuel Flow and Pressure Gages
Fuel Drain Valves
Spark Plug Parts (3)
Electrodes
Ceramic Insulator
Metal Shell
Types of electrodes in Spark Plugs
Projected Core Nose
Two-Prong Fine-Wire
Two-Prong Ground
Push-Wire
Heat Range of Spark Plugs (3)
Hot
Normal
Cold
If an engine typically runs hot…
relatively cold spark plug is required
If an engine typically runs cold…
relatively hot spark plug is required
Why do we use magnetos in general aviation? (4)
Superior to battery ignition
Produces a hotter spark at high engine speeds
Self-contained unit
Not dependent on any eternal source of electric energy
Types of Magnetos (8)
Low Tension Magnetos
High Tension Magnetos
Rotating Magnet Magnetos
Inductor Rotor Magnetos
Single Magnetos
Double Magnetos
Flange Mounted Magnetos
Base Mounted Magnetos
Essential Parts of Carburetors (7)
Float Mechanism and its Chamber
Strainer
Main Metering System
Idling System
Economizer System
Accelerating System
Mixture Control System
Float Mechanism
Designed to control the level of fuel in the float chamber
Fuel Strainer
Fuel passes through a strainer screen
Strainers are commonly a fine wire mesh that will intercept any dirt particles
Main Metering System
Controls the fuel feed in the upper half of the engine speed range
Units of the Main Metering System (3)
Main Metering Jet
Main Discharge Nozzle
Passage Leading to the Idling System
Functions of the Main Metering System (3)
Proportion the A/F mixture
Decrease the pressure at the discharge nozzle
Control the airflow at full throttle
Idling System
Delivers fuel only when throttle valve is nearly closed
Accelerating System
Discharges an additional quantity of fuel into the carburetor airstream when throttle is opened suddenly
Economizer System
Opens at high speeds to provide an enriched mixture to reduce burning temperatures an prevent detonation
Mixture Control System
Prevent mixture from becoming too rich at high altitudes
Economize on fuel during engine operation in the low power range
Where do air and fuel mix?
Carburetor
Advantages of fuel injection (5)
Freedom from vaporization icing (carb icing)
More uniform delivery of air fuel mixture to each cylinder
Improved control of fuel/air ratio
Instant acceleration after idling with no tendency to stall
Increased engine fuel efficiency and power
Bendix RSA FI Servo
Designed to meter fuel in direct ratio to the volume of air being consumed by the engine
Done by sensing venturi suction and impact air pressure in the throttle body
In the Bendix RSA FI Servo, throttle valve opening changes…
the velocity of air passing
In the Bendix RSA FI Servo, when air velocity increases… (2)
pressure of the impact tubes remains constant
Air pressure at the venturi decreases
The differential pressure is used as a measurement of…
the volume of air consumed
Parts of the Fuel Injection system (5)
Servo Pressure Regulator
Idle Valve
Manual Mixture Control
Flow Dividers
Fuel Nozzles
Servo Pressure Regulator
Fuel flow to the engine, passing through the metering jet generates a fuel pressure differential with unmetered fuel
Since fuel is metered to direct ratio with the air being consumed, the two opposite forces (fuel and air differentials) are equal
What keeps both diaphragms connected in the Servo Pressure Regulator
Servo Valve
The servo valve opening…
decreases the pressure in the meter fuel chamber
increases the pressure in fuel differential
Idle Valve
Connected to the throttle linkage
Externally adjustable
Limits the area of the main metering jet
Meters fuel accurately in the idle range
Idle mixture is correct when…
the engine gains 25-50 rpm from idle speed when mixture is placed in “idle cutoff”
Manual Mixture Control
A sliding valve
Used by the pilot to effectively reduce the size of the metering jet
Also allows for shutting off the fuel flow to the engine at engine shutdown
By changing the metering jet’s effective size, the pilot has the option of…
manually leaning the mixture
Flow Dividers
a single four way fitting (4 cylinder engine) or a tee that divides flow into two paths
Functions of Flow Dividers (2)
Ensure equal distribution of metered fuel to the nozzles
Provide isolation of each nozzle for clean engine shutdown
At idle, fuel pressure is…
only enough to move the flow divider valve slightly
As engine accelerates…
metered fuel pressure increases
Fuel Nozzles
are of air bleed type
Fuel is discharged inside the nozzle body into a chamber which is vented to atmospheric air pressure
Where are fuel nozzles mounted?
Nozzle is mounted in the intake valve port of the cylinder head
Newton’s Third Law of Motion
Every action has an equal and opposite reaction
Inventors of Gas Turbine Engines
The Chinese - used rockets as weapons in 1232
Who designed the first true gas turbine engine?
Dr. F. Stolze - 1872
What aircraft company flew the first flight of a gas turbine engine?
Ernst Heinkel Aircraft - 1939
Who designed the first turbojet airplane?
Sir Frank Whittle - 1941
What year was the first US jet plane built?
1943
What was the world’s first operational jet fighter
Messerschmitt Me 262 - 1942
Bernoulli’s Principle
Total energy in a column of moving fluid remains constant throughout the column
Total Energy = Potential Energy + Kinetic Energy
Otto Cycle
Intake (Suck)
Compression (Squeeze)
Power (Bang)
Exhaust (Blow)
What is the difference between the Otto Cycle and the Brayton Cycle?
The Brayton Cycle is the same as the Otto Cycle except:
Events occur at the same time
Events occur at different locations within the engine
Subsonic Convergent Duct vs. Divergent Duct
C: Velocity decreases, Pressure and temperature increase
D: Velocity increases, Pressure and temperature decrease
Supersonic Convergent Duct vs. Divergent Duct
C: Air does not speed up but compresses, Velocity decreases, Pressure and density increases
D: Air expands, Velocity increases, Pressure and density decreases
Non-Air vs Air Breathing Engine Types
Non-Air carries all the needed oxygen within their fuel and generates heat by chemical reaction between fuel and an oxidizer
Air Breathing takes air in through the air inlet
Types of Air Breathing Engines (6)
Turbojet
Turboprop
Turboshaft
Turbofan
Pulse-Jet
Ramjet
Turbojet Engine
Takes air in through the air inlet
Compresses the air
Mix compressed air with fuel
Air and fuel mixture ignited and burned
Hot gases passes through turbine
Air forced out of a specially shaped exhaust nozzle forming a high-speed jet
Turboprop Engine
Drives a propeller
A derivative of the turbojet engine
Methods of driving a propellor (2)
Connecting the propeller to the compressor
Connecting the propeller to a turbine separate from the core engine (Free-Turbine Engine)
Turboshaft Engine
Commonly used for helicopters
More efficient at constant RPM required by helicopters
Most drives output shaft with multistage free turbine
Reduction gearbox is remote from the engine
Turbofan Engine
Increased propulsive efficiency
Lower Noise
Lower fuel consumption
Lengthened blades in early stage(s) of low-pressure compressor
Air from the fan section flows around the outside of the core engine
Fan can produce 30-75% of the total thrust
Bypass Ratio
Ratio of the mass or air moved by the fan to the mass of air moved by the core engine
Types of Bypass Ratio (3)
Low-Bypass
High-Bypass
Ultra-High-Bypass
Low-Bypass Ratio
Less than 2 : 1
High-Bypass Ratio
Ratio of 4 : 1 or greater
Ultra-High-Bypass Ratio
Exceeds 30 : 1
Pulse-Jet Engine
Early air-breathing reaction engines
Used as early as World War II in missiles
Ramjet Engine
Simplest type of air-breathing reaction engine
Requires high-velocity air entering the engine to work
Types of Thrust (2)
Net
Gross
Net Thrust
Thrust produced by the engine while in flight
Gross Thrust
Thrust produced by the engine while engine is static and not moving
% RPM
Compressor speed
approximately proportional to the trust being produced by the engine
Used in smaller jet engines
EPR
Engine Pressure Ratio
Ratio of the turbine discharge total pressure to the compressor inlet total pressure
Used in larger jet engines
Ways to increase thrust (3)
Water Injection
Duct Heater
Afterburners
Water Injection
Increases mass airflow and reduces turbine inlet temp.
Increases takeoff thrust by 10-30%
Duct Heater
Fuel is added to the fan-discharge air and burned
Afterburners
Only 25% of air passing through the core is used for combustion
Remaining air used for cooling
Fuel is sprayed into the hot exhaust gases and ignited
Additional heat further accelerates the air to create 50% increase in thrust
Threefold increase in fuel consumption
