15.7 Exhaust (Level 1, 3 Questions)

Question 1

How much of the total thrust does the exhaust system contribute in a turboprop engine?
A. Most of it
B. All of it
C. A small portion

Answer 1

C. A small portion

Question 2

What is the main task of the exhaust system on a jet engine?
A. Reduce noise
B. Accelerate airflow to generate thrust
C. Cool turbine blades

Answer 2

B. Accelerate airflow to generate thrust

Question 3

What are the components of the exhaust cone assembly?
A. Outer shell, inner cone, radial struts, tie rods
B. Turbine shaft, fan blades, cone tip
C. Fuel lines, cooling ducts, intake fan

Answer 3

A. Outer shell, inner cone, radial struts, tie rods

Question 4

What do the radial struts in the exhaust cone help do?
A. Increase temperature
B. Straighten swirling exhaust gases
C. Increase turbulence

Answer 4

B. Straighten swirling exhaust gases

Question 5

What is the angle at which exhaust gases would leave the turbine without strut correction?
A. 90°
B. 30°
C. 45°

Answer 5

C. 45°

Question 6

What are two common methods for protecting the fuselage from exhaust heat?
A. Mufflers and silencers
B. Blankets and cooling fluid
C. Insulation blankets and shrouds

Answer 6

C. Insulation blankets and shrouds

Question 7

What is the primary purpose of insulation blankets?
A. Increase exhaust velocity
B. Reduce heat loss from the exhaust system
C. Absorb engine vibration

Answer 7

B. Reduce heat loss from the exhaust system

Question 8

Which nozzle design is used for subsonic gas velocities?
A. Convergent
B. Divergent
C. Convergent-divergent

Answer 8

A. Convergent

Question 9

Which nozzle design is used for supersonic gas velocities?
A. Fixed
B. Convergent
C. Convergent-divergent

Answer 9

C. Convergent-divergent

Question 10

In a ducted fan engine, how does the fan airflow exit the engine?
A. Through separate nozzles
B. Through closed ducts into a common nozzle
C. Directly into the atmosphere

Answer 10

B. Through closed ducts into a common nozzle

Question 11

What must be done to core airflow before exiting through the nozzle?
A. Accelerated
B. Cooled
C. Straightened

Answer 11

C. Straightened

Question 12

Using a converging nozzle increases gas velocity and can increase thrust by:
A. 5–10%
B. 15–20%
C. 25–30%

Answer 12

B. 15–20%

Question 13

What type of nozzle has no moving parts?
A. Variable area
B. Fixed
C. Divergent

Answer 13

B. Fixed

Question 14

When is a variable area exhaust nozzle used?
A. During idle
B. With afterburner operation
C. In subsonic flight

Answer 14

B. With afterburner operation

Question 15

What can happen if the exhaust nozzle area is too small?
A. Thrust is wasted
B. Engine may choke or stall
C. Fuel flow stops

Answer 15

B. Engine may choke or stall

Question 16

What happens in the convergent part of a nozzle?
A. Velocity decreases
B. Pressure increases
C. Gas velocity increases

Answer 16

C. Gas velocity increases

Question 17

What is the rear part of a convergent-divergent nozzle?
A. A convergent duct
B. A divergent duct
C. A fan duct

Answer 17

B. A divergent duct

Question 18

What happens in the convergent part of a nozzle?
A. Velocity decreases
B. Pressure increases
C. Gas velocity increases

Answer 18

C. Gas velocity increases

Question 19

What is a common type of noise suppressor in gas turbine engines?
A. External silencer units
B. Acoustic cones
C. Integral part of engine installation or exhaust nozzle

Answer 19

C. Integral part of engine installation or exhaust nozzle

Question 20

What causes the noise produced by the engine exhaust?
A. Fan blade vibration
B. High-velocity jet stream moving through a quiet atmosphere
C. Fuel combustion noise

Answer 20

B. High-velocity jet stream moving through a quiet atmosphere

Question 21

What kind of noise is created a few nozzle diameters downstream when little mixing has occurred?
A. Very low-frequency noise
B. High-frequency noise
C. No audible noise

Answer 21

B. High-frequency noise

Question 22

What happens to the frequency of noise as the jet stream slows and mixes with the atmosphere?
A. It increases
B. It becomes ultrasonic
C. It becomes lower frequency

Answer 22

C. It becomes lower frequency

Question 23

What effect does operating an engine at lower power settings have on noise?
A. Increases it
B. Reduces it
C. Has no effect

Answer 23

B. Reduces it

Question 24

Why is a fan-type engine quieter than a turbojet of similar size?
A. It uses fewer rotating parts
B. It runs at a lower temperature
C. Its exhaust gas velocities are slower

Answer 24

C. Its exhaust gas velocities are slower

Question 25

What do corrugated perimeter and multi-tube type suppressors do to the exhaust stream? A. Split it into smaller streams B. Redirect it downward C. Cool it instantly

Answer 25

A. Split it into smaller streams

Question 26

What is the effect of splitting the jet stream into smaller streams? A. It makes the sound louder B. It changes the frequency and increases atmospheric absorption C. It cools the exhaust gases

Answer 26

B. It changes the frequency and increases atmospheric absorption

Question 27

What does the acoustic lining between the engine and cowl do? A. Reflects heat B. Converts acoustic energy into heat C. Channels fuel

Answer 27

B. Converts acoustic energy into heat

Question 28

What is the purpose of a thrust reverser? A. To increase engine thrust B. To reduce fuel consumption C. To deflect exhaust gas in the opposite direction

Answer 28

C. To deflect exhaust gas in the opposite direction

Question 29

When can thrust reversers usually be used? A. Only during takeoff B. Only when the aircraft is on the ground C. At any time during flight

Answer 29

B. Only when the aircraft is on the ground

Question 30

Which part of the airflow is reversed in modern turbofan engines? A. Exhaust gas B. Core airflow C. Fan airflow

Answer 30

C. Fan airflow

Question 31

What is a clamshell type thrust reverser? A. A fixed nozzle that redirects fan air B. A reverser installed in front of the exhaust nozzle using rotating doors C. A system of external fins that deploy on landing

Answer 31

B. A reverser installed in front of the exhaust nozzle using rotating doors

Question 32

How is the clamshell type thrust reverser operated? A. Manually B. Electrically C. Pneumatically using HP compressor bleed air

Answer 32

C. Pneumatically using HP compressor bleed air

Question 33

What is a bucket door type thrust reverser? A. A movable duct section on the nacelle B. A hydraulically operated system at the exhaust nozzle C. A spring-loaded deflector on the wing

Answer 33

B. A hydraulically operated system at the exhaust nozzle

Question 34

What does a fan reverser do? A. Blocks core flow completely B. Deflects cold fan air using cascade vanes C. Directs hot gas through additional nozzles

Answer 34

B. Deflects cold fan air using cascade vanes

Question 35

How does a pivoting door reverser work? A. Uses magnetic fields to redirect exhaust B. Uses internal vanes to recirculate gas C. Uses doors to deflect fan airflow forward

Answer 35

C. Uses doors to deflect fan airflow forward

Question 36

What issue can occur if thrust reversers are used at low aircraft speeds? A. Increased climb rate B. Compressor stall from reversed airflow ingestion C. Decreased cabin pressure

Answer 36

B. Compressor stall from reversed airflow ingestion

Question 37

Why is airflow direction important on twin-engine aircraft during reverse thrust? A. To prevent overheating the wing B. To ensure airflow does not enter main wheel well or raise dirt C. To reduce fan speed

Answer 37

B. To ensure airflow does not enter main wheel well or raise dirt

Question 38

On a four-engine aircraft, what must be considered with reverse thrust? A. Thrust must be symmetrical B. Noise levels must be reduced C. Reverse airflow must not be ingested by neighboring engines

Answer 38

C. Reverse airflow must not be ingested by neighboring engines

Question 39

What happens even with a defective thrust reverser system? A. The aircraft is grounded immediately B. It can be released for service if correctly deactivated C. The engine is shut down permanently

Answer 39

B. It can be released for service if correctly deactivated

Question 40

What is thrust vectoring used for in military aircraft? A. For fuel efficiency B. To change flight direction by adjusting exhaust nozzle C. To balance weight

Answer 40

B. To change flight direction by adjusting exhaust nozzle