15.3

Question 1

Describe a diverging duct

Answer 1

Air is tighter as it enters and widens as it exits

Question 2

Describe a converging duct

Answer 2

Air is wider as it enters and thins out as it exits

Question 3

For air to smoothly flow into compressor the velocity should be what?

Answer 3

Between 0.4 and 0.7 Mach

Question 4

Air inlets are designed to do what to airflow?

Answer 4

Decelerate it

Question 5

Poor air pressure and velocity distribution results in what?

Answer 5

Compressor stall

Question 6

During flight the inlet ducts covert kinetic energy to what?

Answer 6

Pressure energy

Question 7

The ideal compressor inlet pressure should be the same as what?

Answer 7

Total head pressure at air inlet lip

Question 8

What is the most efficient inlet configuration for subsonic flight?

Answer 8

The pitot type quasi-circular diffuser

Question 9

To reduce flow separation, what can you do to the inlet lip?

Answer 9

Make inlet lip well rounded

Question 10

What do cross winds cause?

Answer 10

Stall

Question 11

A pitot type intake design is only practical when?

Answer 11

Relatively low supersonic mach numbers up to 1.5

Question 12

Where and what is the critical condition?

Answer 12

Shockwave forms on inlet lip in the optimum position

Question 13

What and where is the sub critical condition?

Answer 13

The shockwave detached from the inlet lip and moves further upstream. Reduces Mach number

Question 14

What are where is the super critical condition?

Answer 14

When airflow demand is stronger than inlet can provide and pressure drops
Shockwave is swallowed

Question 15

Negative effects of super critical condition?

Answer 15

Airflow enters inlet at supersonic velocity
Shockwaves occur before compressor and causes flow separation into compressor

Question 16

What is pitot efficiency percentage?

Answer 16

96-99%

Question 17

What is wing root efficiency?

Answer 17

87-95%

Question 18

What is side efficiency?

Answer 18

80-89%

Question 19

What is turbo prop annular (dart) efficiency?

Answer 19

74-82%

Question 20

Describe a normal shockwave?

Answer 20

Pressure rises rapidly
Direction of flow across shockwave remains constant
Not all kinetic energy converts to pressure energy-large amounts turns to unusable heat

Question 21

Describe an oblique shockwave?

Answer 21

Airflow is forced to change direction
Airflow changes in value even though still supersonic

Question 22

Describe bow wave?

Answer 22

Adjacent parts of the wave will bend in a downstream and then cause an oblique shockwave

Question 23

What can ice cause for engine?

Answer 23

Disturbs the airflow and leads to compressor stall
Engine can consume ice and can damage it

Question 24

Engines have what type of anti ice system?

Answer 24

Thermal anti ice system

Question 25

What are some requirements for anti icing systems?

Answer 25

Reliable Ease of maintenance No excess weight No appreciable loss of engine power

Question 26

Thermal anti ice systems are sub divided to what?

Answer 26

Bleed air Electrical heating

Question 27

Apart from thermal systems, what are other methods of anti icing?

Answer 27

Hot oil Rubber spike

Question 28

What are the indications given on anti ice systems?

Answer 28

A- Value not in position selected B- Low duct pressure C- High duct pressure D- Low duct temperature E- High duct temperature

Question 29

Operation or the A-E indications causes what?

Answer 29

Causes a latched relay to trip, locks the system out until it has been reset

Question 30

Pressing the engine anti icing switch/light on energises what?

Answer 30

The thermal anti icing valve (TAI)

Question 31

The amber anti icing light inside the switch illuminates till when?

Answer 31

Until the low pressure switch sense a duct pressure of more than 5 psi

Question 32

Duct over pressure are signalled to where?

Answer 32

EICAS/ECAM

Question 33

Process of anti ice system

Answer 33

-hot air enters anti ice duct -hot air sprays through small holes into engine cowling -hot air heats up leading edge -air leaves through lower part of structure

Question 34

What electrical supply is for the ice protection systems?

Answer 34

Either AC or DC

Question 35

What are the figures for FAST and SLOW on the ice protection cyclic sequence?

Answer 35

FAST (ON/OFF) 2 minutes OAT between -6 and 10 degrees c SLOW (ON/OFF) 6 minutes OAT below -6 degrees c

Question 36

At temperature between 10 degrees and -6 what cycle is selected

Answer 36

FAST

Question 37

At temperatures below -6 degrees what cycle is selected?

Answer 37

SLOW

Question 38

What should heater mats be examined for?

Answer 38

Splits Wrinkling Tears Discolouration (due to overheating)

Question 39

To avoid corrosion what must be renewed when tears are noticed?

Answer 39

Anti corrosion strips

Question 40

When should functional testing of complete anti/de icing system be carried out?

Answer 40

-Periods specific in approved maintenance schedule -When a system malfunction occurs -When a new/overhauled mats have been installed -After component replacement -After repairs to mats