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M15 > 15.3 > Flashcards

15.3 Flashcards

1
Q

Describe a diverging duct

A

Air is tighter as it enters and widens as it exits

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2
Q

Describe a converging duct

A

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

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3
Q

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

A

Between 0.4 and 0.7 Mach

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4
Q

Air inlets are designed to do what to airflow?

A

Decelerate it

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5
Q

Poor air pressure and velocity distribution results in what?

A

Compressor stall

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6
Q

During flight the inlet ducts covert kinetic energy to what?

A

Pressure energy

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7
Q

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

A

Total head pressure at air inlet lip

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8
Q

What is the most efficient inlet configuration for subsonic flight?

A

The pitot type quasi-circular diffuser

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9
Q

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

A

Make inlet lip well rounded

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10
Q

What do cross winds cause?

A

Stall

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11
Q

A pitot type intake design is only practical when?

A

Relatively low supersonic mach numbers up to 1.5

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12
Q

Where and what is the critical condition?

A

Shockwave forms on inlet lip in the optimum position

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13
Q

What and where is the sub critical condition?

A

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

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14
Q

What are where is the super critical condition?

A

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

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15
Q

Negative effects of super critical condition?

A

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

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16
Q

What is pitot efficiency percentage?

A

96-99%

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17
Q

What is wing root efficiency?

A

87-95%

18
Q

What is side efficiency?

A

80-89%

19
Q

What is turbo prop annular (dart) efficiency?

A

74-82%

20
Q

Describe a normal shockwave?

A

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

21
Q

Describe an oblique shockwave?

A

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

22
Q

Describe bow wave?

A

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

23
Q

What can ice cause for engine?

A

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

24
Q

Engines have what type of anti ice system?

A

Thermal anti ice system

25
Q

What are some requirements for anti icing systems?

A

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

26
Q

Thermal anti ice systems are sub divided to what?

A

Bleed air
Electrical heating

27
Q

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

A

Hot oil
Rubber spike

28
Q

What are the indications given on anti ice systems?

A

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

29
Q

Operation or the A-E indications causes what?

A

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

30
Q

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

A

The thermal anti icing valve (TAI)

31
Q

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

A

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

32
Q

Duct over pressure are signalled to where?

A

EICAS/ECAM

33
Q

Process of anti ice system

A

-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

34
Q

What electrical supply is for the ice protection systems?

A

Either AC or DC

35
Q

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

A

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

36
Q

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

A

FAST

37
Q

At temperatures below -6 degrees what cycle is selected?

A

SLOW

38
Q

What should heater mats be examined for?

A

Splits
Wrinkling
Tears
Discolouration (due to overheating)

39
Q

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

A

Anti corrosion strips

40
Q

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

A

-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

M15 (18 decks)

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