15.12 Air Systems (Level 1, 2 Questions)

Question 1

Why is cooling provided to internal combustion engines?
A. To reduce noise
B. Due to intense heat generated during combustion
C. To improve airflow

Answer 1

B. Due to intense heat generated during combustion

Question 2

Without cooling air, what could the internal engine temperature reach?
A. 1150°C
B. 800°C
C. 2200°C

Answer 2

C. 2200°C

Question 3

With cooling air, what is the maintained internal engine temperature range?
A. 400–600°C
B. 800–1150°C
C. 1500–1800°C

Answer 3

B. 800–1150°C

Question 4

Where is the hottest section of the turbine engine?
A. Around the turbines
B. Near the air intake
C. Around the fan case

Answer 4

A. Around the turbines

Question 5

What function does secondary air perform?
A. Powers the fan
B. Increases fuel flow
C. Cools the combustion chamber liners

Answer 5

C. Cools the combustion chamber liners

Question 6

What moves over the surfaces of the combustion chamber liners for cooling?
A. Oil
B. Thin fast-moving film of air
C. Water vapor

Answer 6

B. Thin fast-moving film of air

Question 7

What type of cooling do some engines use for bearings?
A. Water and oil
B. Air and oil
C. Steam and air

Answer 7

B. Air and oil

Question 8

Where is internal cooling air bled from?
A. Fan blades
B. Turbine shaft
C. Compressor section

Answer 8

C. Compressor section

Question 9

How is air vented to or from the engine removed?
A. Manually
B. Using exhaust stream assistance
C. Through the fan intake

Answer 9

B. Using exhaust stream assistance

Question 10

What isolates the primary zones of turbine engines?
A. Electrical panels
B. Plastic dividers
C. Fireproof bulkhead or seals

Answer 10

C. Fireproof bulkhead or seals

Question 11

Which is not a primary engine zone?
A. Fan case compartment
B. Cargo hold
C. Core engine compartment

Answer 11

B. Cargo hold

Question 12

How is Zone 1 vented?
A. Using exhaust stream
B. With ram air through an inlet and vented through right fan cowling
C. Through the turbine exhaust

Answer 12

B. With ram air through an inlet and vented through right fan cowling

Question 13

How is Zone 2 cooled and vented?
A. Cooled by ram air and vented to the intake
B. Cooled by core air and vented downward
C. Cooled by fan air and exhausted into fan stream

Answer 13

C. Cooled by fan air and exhausted into fan stream

Question 14

What does Zone 3 contain?
A. Wing flaps
B. Fuel and oil lines
C. Passenger seats

Answer 14

B. Fuel and oil lines

Question 15

Which engine sections use cooling air?
A. Only the fan
B. Only the combustion chamber
C. Compressor, combustion, and turbine sections

Answer 15

C. Compressor, combustion, and turbine sections

Question 16

What can ice do to a turbine engine compressor?
A. Increase airflow
B. Disrupt the compressor and reduce engine efficiency
C. Improve fuel efficiency

Answer 16

B. Disrupt the compressor and reduce engine efficiency

Question 17

What serious damage can ice cause if it breaks off?
A. It can crack the fuselage
B. It can freeze the cockpit windows
C. It can damage engine blades

Answer 17

C. It can damage engine blades

Question 18

What is generally fitted to engine inlets to prevent ice formation?
A. Dehumidifier system
B. Anti-ice system
C. Fire suppression system

Answer 18

B. Anti-ice system

Question 19

At what temperature can ice form in the inlet due to high inlet velocities?
A. 20°C
B. 15°C
C. 5°C

Answer 19

C. 5°C

Question 20

Why can ice form in the inlet at 5°C?
A. Due to cold fuel temperature
B. Because of the chilling effect of high inlet velocities
C. From high exhaust pressure

Answer 20

B. Because of the chilling effect of high inlet velocities

Question 21

How can anti-icing systems be controlled?
A. Only manually
B. Only automatically
C. Automatically or manually

Answer 21

C. Automatically or manually

Question 22

What part of the engine inlet does the anti-ice system heat?
A. Inner casing
B. Fan blades
C. Lip of the inlet

Answer 22

C. Lip of the inlet

Question 23

Where does the heated air exit after warming the lip?
A. Through the wing
B. Through a grill on the nose cowl
C. Through the exhaust nozzle

Answer 23

B. Through a grill on the nose cowl

Question 24

What are the subsystems of internal engine cooling divided into?
A. Compressor, combustion chamber, fuel tank
B. Compressor, combustion chamber, turbine disc, NGV and blade, accessory section
C. Exhaust nozzle, fan case, intake duct

Answer 24

B. Compressor, combustion chamber, turbine disc, NGV and blade, accessory section

Question 25

What is the typical temperature at the rear stages of the compressor? A. 100–200°C B. 200–300°C C. 350–400°C

Answer 25

C. 350–400°C

Question 26

Where does compressor cooling air come from? A. Combustion chamber B. Intermediate compressor stage C. Exhaust nozzle

Answer 26

B. Intermediate compressor stage

Question 27

What is the combustion chamber made of? A. A solid cylinder B. An outer casing with a perforated inner liner C. A steel block with drilled holes

Answer 27

B. An outer casing with a perforated inner liner

Question 28

What percentage of air enters the combustion liner as primary air? A. 20–30% B. 50–60% C. 70–80%

Answer 28

A. 20–30%

Question 29

What is the role of secondary airflow in the combustion chamber? A. Increases combustion speed B. Heats the liner C. Prevents flames from contacting the liner

Answer 29

C. Prevents flames from contacting the liner

Question 30

What does cooling air in the combustor create on the liner? A. Vibration B. A thermal barrier film C. A solid carbon layer

Answer 30

B. A thermal barrier film

Question 31

Why is turbine cooling key to engine performance? A. To slow down fuel usage B. To increase exhaust noise C. It allows operation 300–400°C above metal alloy limits

Answer 31

C. It allows operation 300–400°C above metal alloy limits

Question 32

What method is commonly used for turbine disc cooling? A. Coolant fluid B. Engine bleed air C. Ice packs

Answer 32

B. Engine bleed air

Question 33

How are Nozzle Guide Vanes (NGV) and turbine blades cooled? A. Fuel mist B. Water injection C. Compressor air

Answer 33

C. Compressor air

Question 34

Why might engine accessories need their own cooling system? A. They are far from the engine B. They produce considerable heat C. They require high pressure

Answer 34

B. They produce considerable heat

Question 35

What is used to cool oil-cooled generators? A. Radiators B. Water jackets C. Air-cooled oil cooler

Answer 35

C. Air-cooled oil cooler

Question 36

What is LP compressor bleed air used for in the engine? A. Fuel injection B. Cooling the turbine blades C. Sealing the engine bearing chambers

Answer 36

C. Sealing the engine bearing chambers

Question 37

What does the pressurised air act on in the bearing chambers? A. Turbine blades and stators B. Air seals and oil seals C. Fan blades and rotors

Answer 37

B. Air seals and oil seals

Question 38

What is the purpose of the pressurised air acting on the seals? A. To increase fuel efficiency B. To provide thrust C. To prevent oil from escaping the bearing chamber

Answer 38

C. To prevent oil from escaping the bearing chamber

Question 39

Where does the air that enters the bearing compartments eventually go? A. Into the combustion chamber B. Vents overboard through the hollow rotor shaft C. Into the turbine casing

Answer 39

B. Vents overboard through the hollow rotor shaft

Question 40

What is a secondary function of the compressor? A. Reducing engine weight B. Supplying air to aircraft systems C. Increasing fuel pressure

Answer 40

B. Supplying air to aircraft systems

Question 41

From which part of the compressor is air often bled? A. Middle pressure stage B. First stage C. Final or highest pressure stage

Answer 41

C. Final or highest pressure stage

Question 42

What are the areas below the engine cowlings divided into? A. Intake and exhaust compartments B. Fan and core compartments C. Compressor and turbine compartments

Answer 42

B. Fan and core compartments

Question 43

What does the external cooling system prevent from building up? A. Fuel in the combustor B. Flammable vapours in engine compartments C. Carbon in exhaust ducts

Answer 43

B. Flammable vapours in engine compartments

Question 44

What separates the fan and core compartments? A. Exhaust ducts B. Heat exchangers C. Bulkheads and seals

Answer 44

C. Bulkheads and seals

Question 45

When is there only positive ventilation of the core compartment? A. When the engine is off B. During maintenance C. When the engine operates

Answer 45

C. When the engine operates

Question 46

What can happen after engine shutdown due to uneven expansion? A. Fan blade crack B. Compressor surge C. Bowed rotor

Answer 46

C. Bowed rotor