Turbine Engines

Powerplant (AMP) ASA Prepware Questions with TURBINE ENGINES

The non-rotating axial-flow compressor airfoils in an aircraft gas turbine engine, are called

stator vanes.

Who establishes mandatory replacement times for critical components of turbine engines?

The engine manufacturer.

Reduce blade vibration and improved airflow characteristics in gas turbines are brought about by

shrouded turbine rotor blades.

The fan rotational speed of a dual axial compressor forward fan engine is the same as the

low-pressure compressor.

Fuel is normally supplied to an APU from the

airplane’s main fuel tank.

If the RPM of an axial-flow compressor remains constant, the angle of attack of the rotor blades can be changed by

changing the velocity of the airflow.

A turbine engine compressor which contains vanes on both sides of hte impeller is a

double entry centrifugal compressor.

Wher is the highest gas pressure in a turbojet engine?

In the entrance of the burner section.

If a turbine engine is unable to reach takeoff EPR before its EGT limit is reached, this is an indication that the

compressor may be contaminated or damaged.

What turbine engine section provides for proper mixing of the fuel and air?

Combustion section.

The compression ratio of an axial-flow compressor is a function of the

number of compressor stages.

Which of the following is a good indication of a malfunctioning fuel nozzle when inspecting the exhaust section of an aircraft turbine engine?

Hotspots on the tail cone.

What type of combustion chamber is used in a turbine engine when engine length is critical?

Reverse-flow.

The function of the exhaust cone assembly of a turbine engine is to

straighten and collect the exhaust gases into a solid exhaust jet.

When aircraft turbine blades are subjected to excessive heat stress, what type of failures would you expect?

Stress rupture.

Turbine engine components exposed to high temperatures generally may not be market with

wax, grease pencil, or a graphite lead pencil.

When necessary, APU engine cooling before shutdown may be accomplished by

closing the bleed air valve.

In which type of turbine engine combustion chamber is the case and liner removed and installed as one unit during routine maintenance?

Can

A weak fuel to air mixture along with normal airflow through a turbine engine may result in

a lean die-out.

The pressure of supersonic air as it flows through a divergent nozzle

decreases

Hot spots in the combustion section of a turbojet engine are possible indicators of

malfunctioning fuel nozzles.

The air passing through the combustion chamber of a turbine engine is

used to support combustion and to cool the engine.

Turbine blades are generally more susceptible to operating damage than compressor blades because of

exposure to high temperatures.

Where do stress rupture cracks usually appear on turbine blades?

Across the leading or trailing edge at a right angle to the edge length.

What type of turbine blade is most commonly used in aircraft jet engines?

Impulse-reaction

Anti-icing of jet engine air inlets is commonly accomplished by

engine bleed air ducted through the critical areas.

An APU is usually rotated during start by

an electric starter

At what point in an axial-flow turbojet engine will the highest gas pressures occur?

At the compressor outlet.

A gas turbine engine comprises which three main sections?

Turbine, compressor, and combustion.

What is the purpose of the diffuser section in a turbine engine?

To increase pressure and reduce velocity.

What are the two basic elements of the turbine section in a turbine engine?

Stator and rotor.

Jet engine turbine blades removed for detailed inspection must be reinstalled in

the same slot.

Which of the following may be used to mark turbine engine components exposed to high temperatures?

Layout dye.

Three types of turbine blades are

impulse, reaction, and impulse-reaction.

The basic gas turbine engine is divided into two main sections: the cold section and the hot section. (1) The cold section includes the engine inlet, compressor, and turbine sections. (2) The hot section includes the combustor, diffuser, and exhaust sections. Regarding the above statements,

Neither 1 nor 2 is true.

The highest heat-to-metal contact in a jet engine is the

turbine inlet guide vanes.

Which two elements make up the axial-flow compressor assembly?

Rotor and stator.

A cool-off period prior to shutdown of a turbine engine is accomplished in order to

allow the turbine wheel to cool before the case contracts around it.

What is one purpose of the stator blades in the compressor section of a turbine engine?

Control the direction of the airflow.

Which of the following influences the operation of an automatic fuel control unit on a turbojet engine?

Burner pressure

One function of the nozzle diaphragm in a turbine engine is to

Direct the flow of gases to strike the turbine blades at the desired angle.

Which of the following engine variables is the most critical during turbine engine operation?

Turbine-inlet temperature.

Usually, most of the load placed on an APU occurs when

the bleed air valve is opened.

The exhaust section of a turbine engine is designed to

impart a high exit velocity to the exhaust gases.

What term is used to describe a permanent and cumulative deformation of the turbine blades of a turbojet engine?

Creep

When in operation, the speed of an APU

remains at or near rated speed regardless of the load condition.

Stator blades in the compressor section of an axial-flow turbine engine

decrease the air velocity and prevent swirling.

Some engine manufacturers of twin spool gas turbine engines identify turbine discharge pressure in their maintenance manuals as

Pt 7

What is the proper starting sequence for a turbojet engine?

Starter, ignition, fuel.

In what section of a turbojet engine is the jet nozzle located?

Exhaust

The pressure of subsonic air as it flows through a convergent nozzle

decreases

Standard sea level pressure is

29.92 inches Hg

The compressor stators in a gas turbine engine act as diffusers to

decrease the velocity of the gas flow.

Which of the following acts as a diffuser in a turbine engine and converts velocity to pressure?

Stators

(1)Welding and straightening of turbine engine rotating airfoils does not require special equipment. (2) Welding and straightening of turbine engine rotating airfoils is commonly recommended by the manufacturer. Regarding the above statements

Neither No. 1 nor No. 2 is true.

At what stage in a turbine engine are gas pressures the greatest?

Compressor outlet.

In an axial-flow compressor, one purpose of the stator vanes at the discharge end of the compressor is to

straighten the airflow and eliminate turbulence.

Hot section inspections for many modern turbine engines are required

on a time or cycle basis.

What is the primary factor which controls the pressure ratio of an axial-flow compressor?

Number of stages in compressor.

The velocity of supersonic air as it flows through a divergent nozzle

increases

Continued and / or excessive heat and centrifugal force on turbine engine rotor blades is likely to cause

creep

The purpose of a bleed valve, located in the beginning stages of the compressor, in an aircraft gas turbine engine is to

vent some of the air overboard to prevent a compressor stall.

Generally, when starting a turbine engine, the starter should be disengaged

after the engine has reached self-accelerating speed.

The turbine section of a jet engine

drives the compressor section.

How does a dual axial-flow compressor improve the efficiency of a turbojet engine?

Higher compression ratios can be obtained.

Which of the following types of combustion sections are used in aircraft turbine engines?

Multiple-can, annular, and can-annular.

What must be done after the fuel control unit has been replaced on an aircraft gas turbine engine?

Retrim the engine.

Some high-volume turboprop and turbojet engines are equipped with two-spool or split compressors. When these engines are operated at high altitudes, the

low-pressure rotor will increase in speed as the compressor load decreases in the lower density air.

Newton’s law of motion, generally termed the “law of momentum,” states:

Acceleration is produced when a force acts on a mass. The greater the mass, the greater the amount of force needed.

Which of the following can cause fan blade shingling in a turbofan engine?

Engine overspeed and / or FOD.

What is the purpose of the dump valve used on aircraft gas turbine engines?

The fuel is quickly cut off to the nozzles and the manifolds are drained preventing fuel boiling off as a result of residual engine heat.

The recurrent ingestion of dust or other fine airborne particulates into a turbine engine can result in

erosion damage to the compressor and turbine sections.

Which statements are true regarding aircraft engine propulsion?

An engine driven propeller imparts a relatively small amount of acceleration to a large mass of air.

The Brayton cycle is known as the constant

pressure cycle.

The blending of blades and vanes in a turbine engine

should be performed parallel to the length of the blade using smooth contours to minimize stress points.

On APUs equipped with a free turbine and load compressor, the primary function of the load compressor is to

provide bleed air for aircraft pneumatic systems.

Which of the following variables affect the inlet air density of a turbine engine?

Speed of the aircraft, altitude of the aircraft, and ambient temperature.

Which of the following is the ultimate limiting factor of turbine engine operation?

Turbine-inlet temperature.

In a turbine engine with a dual-spool, axial-flow compressor, the compressor and high-pressure turbine are

each split into two sections.

What is the possible cause when a turbine engine indicates no change in power setting parameters, but oil temperature is high?

Engine main bearing distress.

A purpose of the shrouds on the turbines blades of an axial-flow engine is to

reduce vibration.

Fuel scheduling during APU start and under varying pneumatic bleed and electrical loads is maintained

automatically by the APU fuel control system.

Using standard atmospheric conditions, the standard sea level temperature is

59 degrees F.

Main bearing oil seals used with turbine engines are usually what type(s)?

Labyrinth and / or carbon rubbing.

What is the first engine instrument indication of a successful start of a turbine engine?

A rise in the exhaust gas temperature.

What is meant by a shrouded turbine?

The turbine blades are shaped so that their ends form a band or shroud.

Which of the following may be used to accomplish internal inspection of an assembled turbine engine?

A borescope.

When the leading edge of a first-stage turbine blade is found to have stress rupture cracks, which of the following should be suspected?

Overtemperature condition.

What is the major function of the turbine assembly in a turbojet engine?

Supplies the power to turn the compressor.

A turbine engine hot section is particularly susceptible to which kind of damage?

Cracking

In a gas turbine engine, combustion occurs at a constant

pressure

When starting a turbine engine

A hot start is indicated if the exhaust gas temperature exceeds specified limits.

The stator vanes in an axial-flow compressor

convert velocity energy into pressure energy.

Generally, when maximum APU shaft output power is being used in conjunction with pneumatic power

pneumatic loading will be automatically modulated to maintain a safe EGT.

Frequently, an aircraft’s auxiliary power unit (APU) generator

is identical to the engine-driven generators.

An advantage of the axial-flow compressor is its

high peak efficiency.

The abbreviation Pt 7 used in turbine engine terminology means

the total pressure at station 7. What is the function of the inlet guide vane assembly on an axial-flow compressor?

The two types of centrifugal compressor impellers are

single entry and double entry.

An exhaust cond placed aft of the turbine in a jet engine will cause the pressure in the first part of the exhaust duct to

increases and the velocity to decrease.

Severe rubbing of turbine engine compressor blades will usually cause

galling.