Powerplant IV Mod 2 Quiz

Turbine Overhaul and Maintenance

What is the recommended method for repairing corrosion pitting on compressor stator vanes?

Blending

What are examples of blade damage in axial-flow and centrifugal-flow engines?

All of the above;

Damage to the outer half of the blade

Nicks and dents in the critical band

Cracks in the leading edges

Why is it important to follow the manufacturer's maintenance and overhaul manuals when performing repairs or inspections on turbine engines?

To ensure proper functioning of the engine

What is the recommended method for cleaning turbine blades during a hot section inspection?

Ultrasonic cleaning

What is the purpose of using a borescope inspection during a hot section inspection?

To check for cracks and warping

What is the importance of following the manufacturer's detailed assembly instructions during engine maintenance?

All of the above;

To extend the engine's service life

To prevent foreign material from entering the engine

To ensure efficient maintenance

Which marking material is recommended for parts directly exposed to the engine's gas path?

All answers are correct;

Felt tip marker and chalk

What method is recommended for inspecting combustion chambers for cracks?

Fluorescent penetrant inspection

Which type of crack is considered the most severe in combustion chambers?

Stress rupture cracks

What is the recommended method for reinstalling turbine blades after inspection?

Numbering the blades and reinstalling them in the same slots

What is the flat rating of a turbine engine?

The guaranteed thrust under specific operating conditions

Why is it important to monitor EGT during takeoff?

To prevent damage to the engine

What is the purpose of the N1 indicator in a turbine engine?

To indicate engine speed

Why is it impractical to measure turbine inlet temperature in most engines?

Because it is too hot

Why are tachometers usually calibrated in percent rpm?

To make it easier to compare different types of engines

What is the purpose of following manufacturer's operating instructions for starting and operating a turbine engine?

To avoid a hot or hung start

What is the appropriate action to take in case of an engine fire during start or ground operation?

Move the fuel lever to the off position and continue cranking or motoring the engine until the fire has been expelled from the engine.

How is the takeoff power for a turboprop engine calculated?

By determining the maximum allowable exhaust gas temperature and torquemeter pressure

What is the purpose of a continuity check in an aircraft EGT circuit?

To eliminate any error caused by one or more inoperative aircraft thermocouples

Why is regular testing and maintenance important for an EGT system?

All answers are correct;

To ensure the accuracy of the EGT indicator

To prevent potential errors in the system

To troubleshoot any issues that may arise

An APU is usually rotated during start by?

An electric starter

Fuel is normally supplied to an APU from

The airplanes main fuel supply

Frequently, an aircraft auxiliary power unit (APU) generator

Is identical to the engine-driven generators

Usually, the most load placed on an APU occurs when

The bleed air valve is opened

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

Automatically by the APU fuel control system

The function of an APU plenum is to

Stabilize the pressure before of the air before it enters the compressor

Standard sea level pressure is:

29.92 in. Hg

When in operation the speed of an APU

Remains at or near rated speed regardless of the load condition

An APU uses aircraft fuel, supplied under pressure by

Electric boost pump

An APU can provide redundancy to aircraft systems by

Providing a back up electrical and pneumatic source

Where is the highest temperature in a turbine engine with respect to the metal parts?

Turbine inlet nozzle vanes

What is the name given to the thermodynamic cycle of a APU gas turbine engine uses to produce electrical or pneumatic power?

Continuous combustion cycle

T or F:
Compressor inlet screens are used on Turboprops and APUs to prevent all FOD from entering the intake of the engine

False

T or F:
APUs are installed in the aircraft and are used to supply electrical power, air hydraulic pressure, and fuel to the aircraft engines when the main engines are not running.

False

T or F:
APU’s are small gas turbine engines or reciprocating-engine that power a generator, hydraulic pump, and air pump.

True

An APU can be operated:

Both A and B;
While the aircraft is in flight and While the aircraft is on the ground

T or F:
An APU is usually manually controlled

False

T or F:

An APU can only be operated while on the ground?

False

An APU is usually rotated during start by:

An electrical starter

Most APU’s have automatic controls for starting, stopping and maintaining operation within safe limits because:

They provide the correct sequencing of the start cycle

Where is the highest gas pressure in a turbojet engine?

At the outlet of the compressor section

The pressure of subsonic air as it flows through a convergent duct :

Decreases Pressure

Name the four basic types of Combustion Sections used in aircraft turbine engines?

Can type, Reverse-flow type, Annular type and Can-annular type

The exhaust section of a turbine engine is designed to

Impart a high exit velocity to the exhaust gases

Using Standard Day Conditions, What is the standard sea level temperature?

59 degrees F

Using Standard Day Conditions, What is the standard sea level pressure?

29.92 in. Hg

What are the two types of compressors used in turbine engines?

Axial and centrifugal flow

Where is the highest temperature in a turbine engine with respect to the metal parts?

Turbine inlet nozzle vanes

What are the three types of turbine blades?

Impulse, reaction and impulse-reaction

What is the name given to the thermodynamic cycle of a gas turbine engine to produce thrust?

Brayton cycle