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M15 > Revision > Flashcards

Revision Flashcards

1
Q

3 advantages of modular engine design to the operator?

A

Considered a minor repair
Easy transportation
Reduced need for spare parts
Modules replaceable on the wing
No re-balancing
Easy removal of modules

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2
Q

When a fan thrust reverser system is designed what must be ensured about the airstream?

A

The cascades direct the air away from other engines and the undercarriage

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3
Q

What effect will increasing the airflow velocity have on the angle of attack of a blade?

A

Decreasing angle of attack

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4
Q

At what angle is the air deflected forward on a cold stream thrust reverser?

A

Between 45 and 60 degrees

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5
Q

what is the optimal fuel/air mix?

A

1:15

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6
Q

What is the purpose of the turbine?

A

To provide the torque to drive the compressor also driving the accessory gearbox.

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7
Q

What effect will ram air have on engine thrust?

A

Engine thrust will increase

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8
Q

What shape does an inlet form?

A

A divergent duct

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9
Q

What percentage of air from the compressor is used for cooling?

A

70-80%

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10
Q

What is meant by the term “sub critical”?

A

The demand from the engine has dropped and the shock wave has been expelled to create a bow wave causing a reduction in pressure

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11
Q

Where are abradable shrouds found on a fan module?

A

On the inner wall of the fan case

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12
Q

What is used in airflow linings to reduce noise and how is itachieved?

A

Honeycomb acoustic liners that convert noise energy (sound waves) into heat energy.

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13
Q

What is the maximum number of stages used on a centrifugal compressor engine?

A

Two

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14
Q

Why is the flame tube only secured at one end?

A

To allow for thermal expansion

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15
Q

What will hotspots on the flame tube indicate?

A

The cooling airflow us not correct or the ceramic lining is damaged

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16
Q

What is the most common method of attaching turbine rotor blades?

A

Fir tree root

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17
Q

What components comprise the combustion section?

A

The casing and the flame tube

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18
Q

What percentage of air from the compressor is used for combustion?

A

20-30%

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19
Q

What are the three different methods of securing rotor blades?

A

Axial dovetail slots, circumferential dovetail slots and bolts/spins

20
Q

On engine shut down what is the contraction sequence of the turbine and the casing?

A

Turbine shrinks faster first then casing shrinks faster after

21
Q

What is the highest heat to metal contact in the engine?

A

1st stage hp turbine ngv

22
Q

How is vibration reduced in LP turbine blade?

A

By the use of shrouds

23
Q

What is the purpose of the exhaust cone?

A

The cone guides the discharge flow and prevents turbulence, it also prevents gas re-ingestion at the turbine frame.

24
Q

What section of the FCU is responsible for engine speed control?

A

The governing section (part of the computing section)

25
Q

What is the purpose of the reverse interlock?

A

To prevent power being increased until the thrust reverser is fully deployed

26
Q

Where on a FADEC engine would you normally find the FCU?

A

There is no FCU fitted to a FADEC engine

27
Q

Why must the engine be run at idle rpm prior to shutdown?

A

It allows the engine to cool down

28
Q

Which of the following pumps has the greater pumping capacity? Pressure or scavenge?

A

Scavenge

29
Q

The engine fuel system is split into which two sub systems?

A

Control and distribution

30
Q

What two methods are available for latching hydraulically operated thrust reverser do in position?

A

A latch mechanism or locks with an actuator

31
Q

What is the purpose of the de-oiler in a vent system?

A

To separate the oil from the air before the air is vented overboard

32
Q

What type of anti-freeze will damage titanium blades?

A

Methanol

33
Q

At what pressure will the frangible disc in a fire bottle burst?

A

1700psi

34
Q

Where do fire extinguisher firing circuits get their power?

A

Hot bus

35
Q

Which compressor is protected by the variable bleed valve?

A

LP compressor

36
Q

What is used for active clearance control on a compressor and why?

A

Warm air is used as there is no source of air cold enough for cooling

37
Q

If bypass fuel is used to cool the IDG, what else is usually fitted and why?

A

A recirculation valve is fitted

38
Q

What systems are affected when the fire button is pressed?

A

Fuel, hydraulic, air & electric

39
Q

What is the definition of a turbo shaft?

A

A gas turbine engine that delivers power to anything other then a prop

40
Q

What is a bowed rotor condition?

A

Where the engine bends due to different contracting and expanding rates due to temperature

41
Q

How does a centrifugal particle separator remove debris?

A

A swirl is intruded into the air flow by vanes, this cause any debris to be flung outwards

42
Q

Why do we have apu on aircraft?

A

Standby source of bleed air and electrical power in the event of engine failure.

43
Q

How is the flame tube protected from extreme temperatures of combustion?

A

By using the secondary airflow

44
Q

What is a compressor stall?

A

Airflow separation from the compressor aerofoils causing turbulent flow across the stage, the engine rpm drops and the engine can run roughly

45
Q

What effect will pneumatic engine anti-icing have on the operation of an engine?

A

EGT will rise as air is bled away from the engine

M15 (1 decks)

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