Final Flashcards
One function of the Nozzle diaphragm of a turbine section is to:
Increase the velocity of the hot gases
An eddy current type RPM indicating systems measures ____________ to indicate rotation speed.
FREQUENCY
The velocity of compressor discharge air is Controlled by:
the taper of the compressor
The highest total pressure in a gas turbine engine occurs at the ___________________outlet.
COMPRESSOR SECTION
Fuel nozzle that has two discharge orifices and a flow divider within the nozzle is called a:
Single Line Duplex Fuel Nozzle
In a typical oil system, the main oil filter is located just
After the main pressure pump
The “waist” mounted accessory gearbox on a gas turbine engine would provide a drive pad for a:
Mechanical fuel pump
The compression ratio of an axial flow compressor:
Varies with engine RPM and inlet air temperature
The stators of one stage of an axial compressor converts?
velocity to static pressure
Three factors that must be considered when repairing fan blades include (1)Structural integrity of the blade and (2)Aerodynamic cross-section. The third factor is:
(3)Balance, and may cause you to remove material from the opposite blade that is not damaged.
An electronic torque meter system measure_______________________to indicate the difference between high and low torque.
TIME DIFFERENCE
An engine is tested, and it is found that maximum RPM is reached before maximum ITT and maximum thrust are reached. One solution is to:
Decrease exhaust nozzle area
In a subsonic inlet, ram recovery point refers to speed (of the aircraft) at which the duct will deliver air to the compressor.
Which has a total pressure equal to ambient air pressure.
During the start sequence, the electric starter is selected off:
After light off but before idle
The velocity of the gas flow through an in-flight turbofan engine will be the lowest at the:
Combustion section inlet
The pilot of an aircraft equipped with turbofan engines looks on a chart to select the EPR for take-off. He will need to know the atmospheric pressure and:
OAT
The exhaust section of a turbojet engine is designed to:
Impart a high exit velocity to the gases
Which is the ultimate limiting factor of engine peak performance?
Turbine inlet pressure
Impingement cooling refers to a method of cooling in which:
Cooler air is directed onto specific parts to carry heat away
The purpose of the combustion liner is to:
Mix fuel and air for the burning of fuel and heating of air
An inefficiency in a compressor that has achieved a target pressure will be revealed by a:
Higher than normal temperature rise
When a turbine engine equipped aircraft in altitude, the thrust decays at a faster rate above the troposphere. This is known as (the):
Thrust lapse rate
Compressor stalls can be avoided by:
Varying the size of the exhaust nozzle
If a cone is placed aft of the disc of the last turbine stage and forms part of the exhaust duct, it will cause the static pressure in the duct to:
Increase
A “two spool” engine on that has two:
Separate compressors and turbine rotors
Where is station #2 located in the engine?
Just in front of the compressor.
The gas velocity in the throat of a chocked nozzle is:
SONIC
Each engine manufacturer uses the standard tach generator RPM, but must _______________________________ to get the correct indication.
DRIVE THE GENERATOR AT THE CORRECT GEAR RATIO
The discharge of the stator to the impulse section of a combination type turbine blade will have a:
Higher velocity than the discharge to the other sections of the blade.
One function of the stator blades in an axial compressor is to:
Convert velocity to static pressure
What is the term describing permanent and cumulative deformation of a material (such as turbine blades) due to heat, and loading?
CREEP
The shape of a subsonic inlet duct is best described as:
A diffusing duct
One function of the stator blades in an axial compressor is to:
Redirect the air and give it proper angle of attack
What causes the discharge flow rate of a constant displacement fuel pump to vary?
RPM
Air pressure in the combustion section:
Must be held as close to constant as possible
on the electro-hydro-mechanical fuel control In the “Normal” (computer) mode, maximum PCD is limited by the:
P3 Limiter
specially on the electro-hydro-mechanical fuel control In “Normal” mode, the governor valve (plate valve) would open at:
105 N2
specially on the electro-hydro-mechanical fuel control A change in power lever position will cause a direct change in:
Py
specially on the electro-hydro-mechanical fuel control The enrichment system is designed to modify:
Px
specially on the electro-hydro-mechanical fuel control Differential pressure between Px and Py is least during:
Acceleration
specially on the electro-hydro-mechanical fuel control Differential pressure between Px and Py is greatest during:
Deceleration
specially on the electro-hydro-mechanical fuel control In the following formula Fn is the best described as representing: Fn = Wa(V2 – V1) = Wf (Vf) = Aj (Pj-Pa) g g
Net thrust
on the electro-hydro-mechanical fuel control xThe NF power turbine governor changes the metering valve position by:
Reducing Py
on the electro-hydro-mechanical fuel control The NG governor valve controls:
Py
In the following formula, 550 represents (A represents Delta): HP = Cp AT Wa (778) 550
1 Horsepower
Which of the FCU inputs comes from the pilot?
Power lever PLA (power level angle
Which of the inputs will establish the density of the air, for the FCU?
Tt2, P2, PDC=P3
In order to increase the RPM the FCU must _____fuel the engine
over
What is the purpose of the minimum flow adjustment in an FCU
allows some fuel to always flow and prevent flame out
What is the purpose of the differential relief valve?
set a constant pressure differential
When the governor speeder spring pressure is equal to the centrifugal force on the flyweights, the governor is referred to as ____________
on speed (flight weights are balance)
When the governor speeder spring pressure is greater than the centrifugal force on the flyweights, the governor is referred to as ____________
under speed (flight weights tips in)
When the governor speeder spring pressure is less than the centrifugal force on the flyweights, the governor is referred to as ____________
over speed (flight weight tip off)
List the 2 methods of accurately metering fuel
-Fix orifice-Variable pressure (normal mode) -Variable orifice - Fixed pressure (manual mode)
When there is the greatest difference between Px and Py, the engine RPM will be _____
decrease
When there is the least difference between Px and Py, the engine RPM will be _____
increase
In a differential pressure fuel metering system, the governor controls the value of _____
Py
in Brayton Cycle the compressor discharge is at point ?
B
In the Thrust formula, what has the effect of increasing Fn?
increasing the weight of the air flow
a Nozzle is choked when ?
sonic velocity is reach at the trhoat
The stators of one stage of an axial compressor converts ?
velocity to static pressure
Most tach generators indicate 100 % when the generator is turning____ RPM
4200
considering the specific heat formula, the power extracted from the gas by the turbines can be calculated if we know (among other things):
Temperature change across the turbines
a large portion of the noise of a turbine comes from
a high differential shear zone
in the specific heat formula what does Cp represents?
air under constant pressure
what is the ultimate factor of engine peak performance ?
Turbine Inlet Temperature TIT
according with the general gas law, if the pressure of the gas decrease and the volume held constant then the temperature will ?
decrease
what does the turbulence of the combustion liner ?
facilitates the mixing of fuel and air
a two spool engine is one that has two ?
separate compressors and turbine rotors
in the thrust formula Fn represents ?
Net thrust
when converting Thrust to horsepower to obtain ESPH for a turbo prop engine (statics conditions ) this formula is used : ESPH =SHP+Fn/X “X” is equal to?
2.5 ( an industry accepted standard)
if a cone is placed aft of the disc of the last turbine stage and forms part of the exhaust duct, it will cause the static pressure in the duct to?
Increase
an increase in OAT affects the performance of a gas turbine in the following way:
decrease thrust
the exhaust section of a turbo jet engine is designed to ?
impart a high exit velocity
Thrust augmentation will be used during ?
Take off
a gas turbine engine is designed to supply power to an airframe supplied transmission would be classify as
turbo shaft
the pilot of an aircraft equipped with turbofan engine looks on a chart to select EPR for take off which 2 parameters are referenced in order to obtain the correct setting ?
OAT, Pressure Ambient
EEC outputs
Manual mode selenoid,torque meter, overspeed selenoid, surge bleed valve (Pneumatic Power)
Fuel is metered in Normal mode by using __________ orifice and _________ pressure
constant, variable
Fuel is metered in Manual mode by using __________ orifice and _________ pressure
variable, constant
In manual mode, the position of the bypass valve is controlled by the ___________
Delta P bellows
in Normal mode, to accelerate the engine the bypass valve must move _______ (direction)
it will drop to increase the fuel flow to the engine
Reduce fuel flow to the engine, the torque motor must ________ the plate valve orifice.
open
P1 pressure is trying to __________ the ΔP bellows
compress
P2 pressure is trying to __________ the ΔP bellows
expand
The purpose of the ΔP bellows is to:
take care of differential pressure
In which mode does the Pcd limiter monitor pressure?
prevent overthrust both modes
What pressure does the Pcd limiter monitor?
pneumatic pressure P3
PL pressure acts on which bellows?
acceleration bellows
Increasing PL pressure will cause the metering valve to ___________
close
In the drawing of the EHM FCU, to reduce fuel flow, the metering valve must move _____ (direction)
up, closing
The cam plate on the power lever shaft sets the RPM in __________ mode
Manual
The PLA Pot sets the RPM in __________ mode
Normal
in Normal mode, the manual mode piston is forced against the stops by _____ pressure
Pr pressure
The fuel shutoff valve is held in the open position by _____ pressure
P2
The Ultimate Overspeed Solenoid is energized by the __________
EEC needs to have computer on to work, normally close
When the Ultimate Overspeed Solenoid is energized, it is in the__________position
open
6 Inputs of the EEC
-N1 -N2 -Tt2 -Pt2 -PLA -ITT
The fuel shutoff valve is held in the open position by _____ pressure
P1
when the metering valve is up is open or close
close
identify A,B,C,D,E,F,
A=Inlet pressurizing valve 140-160 psi
B=by-pass valve
C=Delta P bellows 49-53 psi
D=Accel Bellows
E=Evac Bellows
F=Metrering Valve
identify G,H,I,J,K,L,
G=Outlet pressurization valve
H=fuel shut-off valve
I= Fuel/oil heater
J=Ultimate over speed selenoid
K=flow divider
L= PDC limiter or P3 limiter
identify ,M,N,O,P,Q
M= Manual mode selenoid (N.C)
N= Seed Governor (105% AUTO)N2
O=Fuel boost pump 35-40 psi
P=High Pressure relieve valve 1450 psi
Q=Torque Meter
identify R,ST,U,V
R=Anti ice sensor
S=Overboard drain
T= Anti ice valve
U= High pressure pump
V=Inlet filter
identify W,X,Y,Z
W=Flter by pas 6.5 psi
X=power level
Y=PLA POT Power level angle potenciometer
Z=Electronic Engine Computer
identify 1,2,3,4,5,6
1=Manual mode adjustment
2= metal filter 40 microns
3=rotary valve
4=fuel/oil cooler
5=primary fuel nozzles
6=secondary fuel nozzles
