15.3

Question 1

What does the inlet guide vane do

Answer 1

Straightens the airflow and direct it onto the first stages of the compressor

Question 2

What’s the purpose of a screen on the engine

Answer 2

Prevent FOD

Question 3

What is ram recovery or total pressure recovery and what does it do

Answer 3

The added pressure the inlet that increases pressure and airflow into engine

It compensates for loss of thrust due to increase in airspeed

Question 4

What is the purpose of turning vanes

Answer 4

They are placed inside side-scoop inlet to straighten flow and prevent turbulence

Question 5

What the 2 types of divided ducts

Answer 5

Wing root inlet or a scoop

Question 6

Disadvantage of divided duct arrangement

Answer 6

Sudden manoeuvres provide an imbalance in ram pressure which can cause a slight loss in power

Question 7

Function of an inlet duct

Answer 7

Provide correct amount of air into the engine inlet

Question 8

In a variable geometry duct what must the engine airflow be

Answer 8

Below Mach 1

Question 9

What do inlet ducts act as

Answer 9

Diffusers to decrease the velocity and increasing the static pressure

Question 10

What makes a variable geometry duct VGD ‘variable’

Answer 10

Inside area of the configuration can be changed

Question 11

How can you change the area of VGD

Answer 11

Introduce a restriction such as ramp or wedge in the duct

Question 12

What does a variable airflow bypass arrangement do

Answer 12

Extracts part of the inlet airflow from the duct ahead of the engine

Question 13

What’s the 3rd method to diffuse inlet air

Answer 13

Uses shockwaves into the airstream to decrease velocity of the airflow

Question 14

What does a compressor inlet screen do

Answer 14

Prevent engine from ingesting items into the intake

Can be placed along the inlet duct

Question 15

Disadvantage of compressor inlet screen

Answer 15

Loss of inlet duct pressure and subject to icing

Question 16

Are screens used on the engines with titanium or steel fan blades

Answer 16

No , the disadvantages outweigh the advantages

Question 17

When is a bell mouth compressor inlet used

Answer 17

During testing

Question 18

What is duct loss considered as in bell mouth compressor inlet

Answer 18

0

Question 19

How are turboprop inlets anti iced

Answer 19

Electrical elements in the lip opening of the intake

Question 20

Best arrangement for inlet design on turboprop

Answer 20

Ducted arrangement

Question 21

What’s the function of a conical spinner

Answer 21

Doesn’t allow ice build up on the surface

Question 22

On high bypass turbofan engines where is the fan constructed to

Answer 22

Forward end of the compressor

Question 23

What’s the function of the inlet cowl and where is it placed

Answer 23

Bolted to the front of the engine

Provides airflow path into engine

Question 24

What speed should the fan blades rotate to achieve the best efficiency

Answer 24

Low tip speed

Question 25

How does a fan reduce damage to engine

Answer 25

Throws fod radially outward and goes through fan discharge instead of engine

Question 26

2 ways of anti icing inlets

Answer 26

Warm bleed air from engines and conical spinner

Question 27

What 2 effects can ice have on the engine inlet

Answer 27

Reduce performance that can lead to compressor stall Pieces of ice damage fan blades or inlet vanes

Question 28

What combination do inlets use to keep it free from ice

Answer 28

Warm oil from engine oil reservoir & hot air from compressor/diffuser

Question 29

When are heat strips used

Answer 29

Only when it’s just the cowl that needs anti-icing

Question 30

What conditions does ice form

Answer 30

5 degreess in dry air 7 degrees in moist air (fog and rainy)

Question 31

What engines is bleed air used on

Answer 31

Engines with high-mass airflow

Question 32

Where is bleed air bled from

Answer 32

Bled off the HP compressor

Question 33

What the function of anti-icing valves

Answer 33

Protect against over pressurisation to prevent loss of engine power

Question 34

Where are anti ice valve operated

Answer 34

Automatically via ice detection system or manually in flight deck

Question 35

How is air for the intake ejected overboard

Answer 35

Via small grills

Question 36

What happens to air used for the cone and inlet guide vanes

Answer 36

Directed overboard or back into LP compressor intake

Question 37

How are anti ice valves operated and selected

Answer 37

Selected electrically and pressure operated

Question 38

Low and high duct pressure and temperature causes what

Answer 38

Latched relay to be tripped and locks system out until reset

Question 39

What air does engine anti ice system use

Answer 39

Hot air from pneumatic system or directly from engine

Question 40

Precaution against the doing ground tests on thermal anti-ice system

Answer 40

No personnel should be in the test area during ground tests

Question 41

What’s the manual override function used for

Answer 41

Valve or system failure

Question 42

What does EEC do in terms of anti icing

Answer 42

Controls flow of hot air into the engine inlets

Question 43

What are electric heat strip systems constructed of

Answer 43

Electrical resistance wire embedded in layers of neoprene materials

Question 44

Where are heat strips located

Answer 44

Lip of nacelle

Question 45

What does an inlet guide vane do

Answer 45

Straighten airflow and direct it to the first stages of the compressor