Volume 2 (Engine Theory and Construction) Flashcards
“An unbalanced force on a body produces or tends to produce acceleration in the direction of the force and that the acceleration, if any, is directly proportional to the force and inversely proportional to the mass of the body.” This statement is
Newton’s second law of motion
Which type of duct would decrease the velocity and increase the pressure of a gas as it passes through?
Divergent
What does fuel for an engine represent?
Potential energy
Which section of a jet engine continually supplies air and maintains pressure?
Compressor
Which section of a jet engine introduces and burns fuel?
Combustion
Which section of a jet engine keeps the compressor rotating?
Turbine
Through which section of a jet engine is energy expended into the atmosphere, resulting in thrust?
Exhaust
How many British thermal units (Btu) does the heat content per pound of kerosene produce?
18,500
To measure barometric pressure, you would use a
barometer
What is the sea-level atmosphere pressure in pounds per square inch (psi) at “standard day” conditions?
14.7 psi
What effect does moisture content or humidity have on density of air in a jet engine?
More moisture, less dense
What effect does the divergent design of a diffuser have on air pressure in a jet engine?
Increases pressure
The air temperature of a jet engine gradually rises across the compressor to the diffuser outlet as a result of
compression
Where is the highest point of temperature reached in a jet engine?
Combustion section
Which jet engine component meters fuel for combustion?
Fuel control
What is the required velocity for air and gases flowing through a jet engine?
Greater velocity exiting than entering
What is the general flow of gases from the combustion chamber of the jet engine?
Parallel to the axis of the rotor shaft
What directs the gases onto the first-stage turbine wheel blades in a jet engine?
Turbine stator
When two or more turbine wheels are used in a jet engine, which component is placed directly in front of each turbine wheel?
Turbine stator (nozzle diaphragm)
The operation of any gas turbine engine, regardless of type, requires the provisions to be made for three major functions. What are they?
Compression of air, expansion of air by burning fuel, and extraction of power from gases for driving the compressor and engine driven accessories
The three major sections of all jet engines are compressor, combustion, and
turbine
Vane-type fuel pumps used in jet engines are similar to
sliding-vane air compressors
Which condition reduces the efficiency of a centrifugal compressor?
Pressure pulsations
A constructional feature of the centrifugal compressor is that the impeller
is forged as a single unit
In a dual-spooled compressor, revolutions per minute (rpm) of the N2 compressor are determined by the
fuel control
The jet engine compressor that is cheaper to manufacture is the
centrifugal type, because of its fewer parts
Which is a constructional feature of an axial-flow compressor casing?
Split horizontal centerline
The percentage of combustion efficiency of a gas turbine is usually between
95 and 100
Which facet of jet engine design helps prevent igniter plug fouling?
Directing air around the plug
Carbon monoxide gas is poisonous and odorless, and has
no color
What is the most chemically correct ratio for burning fuel in a combustion chamber of a jet engine?
15:1
The excess airflow that is not burned in the combustion section of the jet engine is used to
cool the burner surfaces
The inner and outer surfaces of an annular-type combustion chamber are formed by
interlocking stainless-steel bands
Fuel that accumulates after a failed engine start is
drained overboard by a drain system
The parts of a can-annular combustion section must be removed in a specific order because of the
combustion chamber crossover tubes
What is the most common type of fuel nozzle system?
Pressure-atomizing
Three types of turbine and vane assemblies used in jet engines are impulse, reaction, and
reaction-impulse
In the reaction type turbine, what in the design causes the rotor to burn?
The reduction in pressure and the increase in velocity of the exhaust gases occur in the passage between the rotor blades
The “fir tree” method of attaching turbine blades (buckets) to the turbine rotor disc is preferred because
of the temperature differential between the turbine rotor disc and the blades
Which method of attaching the turbine blades (buckets) to the turbine rotor disc is used most frequently?
Series of grooves or notches broached in the rim of the turbine rotor disc
The fan exhaust duct connects the turbine outlet and the
jet nozzle
The design of an exhaust duct straightens the exhausts gases as it leaves the last stage of the turbine section to provide for
larger total thrust in a more efficient manner
The rear opening of the exhaust duct on the jet engine is referred to as the
exhaust nozzle
Some jet engines are trimmed/adjusted to their correct exhaust gas temperature by an alteration of what?
Exhaust nozzle area
How many different types of loads can be imposed on a jet engine bearing?
Three
Before inspecting new jet engine bearings, you should
remove the preservative coating
Next to contamination and improper lubrication, what is the greatest enemy of anti friction bearings?
Improper removal
The most commonly used bearing removal tools include
arbor presses and bearing pullers
Which type of defect appears on bearings as a result of bearing parts striking together?
Nicks
Which type of bearing defect results from inadequate lubrication?
Galling
Excessive bearing wear can usually be detected by
roughness of the metal
Before you install separable bearings in a jet engine, you must make sure the
bearings are a matched set
To cause an accessory in a jet engine to operate at its most optimum speed, design engineers must
change the gear ratio
On an F108 engine, the radial drive shaft connects the core engine to the
accessory drive assembly
Which F108 major engine module provides for mounting of the front of the engines to the airframe?
Fan major module
Power to drive the accessory gearbox (AGB) on the F108 engine is transmitted from the
accessory major module
F108 structural rigidity is obtained with a short length and by having only two main structures that are called
mainframes
Primary airflow in the F108 engine is through all of the following components except the
accessory gearbox
Which types of load does the No. 2 bearing take up in the F108 engine?
Radial
The F108 engine has an air duct through the inside diameter of the core compressor rotor that forms a flow path for
pressurizing and cooling airflow
On the F108 engine, the combustion chamber is of which design type?
Annular
On the F108 engine, the low-pressure turbine (LPT) shaft assembly connects the fan shaft with the
LPT rotor
On the F108 engine, as gases flow through the convergent passageways of the low-pressure turbine (LPT) nozzle their pressure drops, and their axial velocity
increases
The F108 engine turbine frame is the engine rear main structural component, and it supports the
LPT rotor rear section
On the F108 engine, what connects the inlet gearbox (IGB) to the transfer gearbox (TGB) bevel gears?
Radial drive shaft
On the F108 engine, how is the transfer gearbox (TGB) mounted to the fan case?
By a single clevis-and-link rod-mounting arrangement
On the TF34 jet engine, the fan forward shaft, bolted to the aft side of the double disc, is supported by
both the No. 1 thrust ball bearing and the No. 2 roller bearing
The single-stage fan rotor on the TF34 jet engine provides what percentage of the engines thrust?
85 percent
On the TF34 jet engine, which strut does the fan speed pickup protrude through to the number two bearing locknut?
9 o’clock
The compressor inlet temperature sensor is mounted on the outer surface of the splitter nose at what “o’clock” position on the TF34 jet engine?
9 o’clock
How many stages of compressor blades are in the TF34 engine?
14
Why is the compressor stator case split horizontally?
To allow access to the compressor rotor
What stages of compressor vanes are variable in the TF34 engine?
Stages 1-5
What type of combustion liner does the TF34 have?
Annular
On the TF34 jet engine, the first-stage nozzle consists of 24 cast segments with how many vanes in each segment?
2
What is the purpose of the low-pressure turbine (LPT) transition assembly?
To funnel hot gases from the HPT rotor to the larger diameter LPT rotor
On the TF34 jet engine, which strut is used to port seventh stage compressor air into the C-sump area to pressurize the number six carbon seal?
12 o’clock
Which of these items does not belong to the TF34 engine accessories section?
Compressor stator
In order to facilitate borescoping the engine, what is provided for rotating the high-pressure rotor system and where is it located?
A gearbox cranking pad located between the lube and fuel pump pads
Which one of these compressor section subsystems does not belong on the F117-PW-100 jet engine?
High-pressure turbine (HPT) group
The high-pressure compressor (HPC) group on the F117-PW-100 jet engine consists of how many rotor stages and how many stages of rotors surrounded by a two section titanium and steel case?
12 rotors and 12 stators
How many exit vanes make up the compressor exit stator assembly on the F117-PW-100 jet engine?
72
The combustion chamber assembly provides the optimum environment for combustion and directs the flow of
hot gases to the turbine nozzle
Which of these turbine section subsystems does not belong on the F117-PW-100 jet engine?
Low-pressure compressor (LPC) nozzle group
Which one of these components is not an engine accessory component on the F117-PW-100 jet engine?
Radial drive shaft
Which one of the listed components is not an aircraft accessory component on the F117-PW-100 jet engine?
Low-pressure turbine (LPT) module
