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M15 > POWERPLANT INSTALLATION > Flashcards

POWERPLANT INSTALLATION Flashcards

1
Q

What are powerplants divided into cooling zones by means of?

A

Fireproof bulkheads (firewalls)

Made from steel, titanium or thermoplastics.

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2
Q

What does the engine nacelle do?

A

Give the engines a necessary aerodynamic smoothness and protects engine components from damage.

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3
Q

What size dents are allowed in class 1 aerodynamic areas?

A

Only very small dents.

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4
Q

What gives undisturbed airflow around the pylon?

A

Fairings.

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5
Q

What part of the air intake can be heated to prevent build up of ice?

A

Nose lip.

Spray duct distributes hot air.

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6
Q

Why does the inner barrel have acoustic linings?

A

Reduce noise radiation from the fan.

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7
Q

What are index pins for?

A

Ensures the engine cowl can only be installed in the correct position.

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8
Q

What part of the engine covers the accessory gearbox?

A

Fan cowling.

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9
Q

What is the fan cowling usually made of?

A

Sheet metal or composite materials.

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10
Q

How many latches is the lower part of each fan cowling fastened to the opposite cowling?

A

3 or more.

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11
Q

What ducts do the fan air pass through in the fan reverser cowling?

A

C ducts (because of shape)

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12
Q

What is the fan reverser cowling made of?

A

Steel or titanium

Composites for skin only

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13
Q

How can the fan reverser cowling only be opened?

A

Hydraulic pressure.

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14
Q

What is cowl load sharing for fan reverser cowling?

A

Uses V shaped grooves and blades that give good contact to the engine fan frame.

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15
Q

Which cowling has 2 passive fire protection features preventing fire from hot sections reaching other areas of the aircraft.

A

Fan reverser cowling.

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16
Q

What is the fire seal on the fan reverser cowling connection to the fan frame made of?

A

Titanium with heat resistant silicon layer

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17
Q

What is the core cowling always made of?

A

Metal, covers hot section.

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18
Q

What 2 components is the exhaust nozzle made up of?

A

Centre body

Exhaust sleeve

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19
Q

What engines have reduced exhaust signature?

A

High bypass fan engines. Turbines extract most energy from gas stream.

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20
Q

How do acoustic panels reduce noise?

A

Noise absorbing materials convert noise energy to heat energy.

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21
Q

What materials are used for low temperature and high temperature areas in the acoustic panel?

A

Low- lightweight composites

High- fibrous-metallic materials

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22
Q

What is the noise absorbing material made up of in acoustic panels?

A

Perforated metal or composite facing skin, supported on honeycomb structure.

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23
Q

What size are acoustic panels?

A

Air intake- 1 inch thick

Inner fan case and outer casings- 1-1.5 inch thick

Exhaust cone- 0.5 inch thick

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24
Q

What does the compartment ventilation exhaust discharge?

A

Air that was used to cool core engine cases.

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25
Q

How is the pressure relief door usually held shut?

A

Closed by a spring.

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26
Q

What does a lanyard do in the pressure relief valve?

A

Prevents panel from flying away.

27
Q

How are holes usually covered to prevent anything entering?

A

Plastic covers fixed with strips or tape, special plastic plug for exhaust nozzle.

28
Q

What are engines under the wing called?

A

Wing mounted engines.

29
Q

What is the pylon where all engines are fitted on?

A

Engine strut.

30
Q

How many mounts is the engine usually connected to the pylon by?

A

2

Forward mount- to fan frame

Aft mount- to turbine frame

31
Q

What do the engine mounts do?

A

Transfer all forces from the engine to the pylon.

32
Q

What axis does the engine weight act in?

A

Vertical axis (known as z axis)

Carried by forward and aft mounts.

33
Q

What axis does the engine thrust act in?

A

Longitudinal axis (also called x axis)

Axial force, only supported by forward mount.

34
Q

What axis do side loads act in?

A

Lateral axis (also known as y axis)

Generated by flight manoeuvres, transferred by forward and aft mount.

35
Q

Why is thrust only transferred by the forward mount?

A

The axial thermal expansion of engine (can be more than 20mm) must not generate force to mounts.

36
Q

How is the forward mount connected to the pylon by?

A

4 attachment bolts.

Vertical engine loads

37
Q

On the forward mount, how are thrust and side loads transferred?

A

Shear pins.

38
Q

What construction is the support beam for forward engine mount?

A

Fail safe.

Loads can be shared between remaining 2 connections if one breaks.

39
Q

What type of anti-vibration mounts are used on turboprop?

A

Resilient rubber mounts.

Need to be inspected for heat and fluid deterioration

40
Q

What is PTFE used for in hoses?

A

High pressure applications.

-54 to 223 celsius and on most fluids.

41
Q

The does the use of steel for pipes permit?

A

Use of thinner walls, no excessive weight gains.

42
Q

What are feeders?

A

Cables which take power to and from a component.

43
Q

What design are most connectors found on modern aero engines?

A

Bayonet design.

44
Q

How are wiring looms and bundles secured?

A

Dacron lacing cord.

(Nylon tie wraps not permitted)

As engines high vibration areas, no more than 2 inches apart.

45
Q

What is the bootstrap method for engine change?

A

Uses a beam attached to the top of the pylon with quick release pins.

Standard method for all wing mounted engines.

Requires a long time.

46
Q

What is the crane supported sling method?

A

More expensive equipment but about 30% less time than bootstrap.

Sling connected with 2 chain hoists.

47
Q

What is the uplift loader method of engine change?

A

Expensive special equipment. (Not commonly used)

Fastest time (40% faster than bootstrap)

48
Q

Why are friction dampers fitted to the throttle lever assembly?

A

Prevent movement from vibration.

49
Q

What are the components of an engine drain system?

A

Drain lines

Module assembly where all drain lines end

50
Q

What is the lower part of a drain system called which puts the fluids overboard?

A

The drain mast

51
Q

What typical areas would you find component leaks?

A
  • pylon
  • fuel operated VBV and SVS actuators and servo valves
  • oil tank scubber
  • fuel oil heat exchanger
52
Q

Where can drain lines be found?

A
  • drive pads of the HMU
  • Starter
  • IDG
  • fuel oil and hydraulic pumps
53
Q

How is a fire risk in the pylon drain outlet minimised?

A

The most important outlet drains fuel directly overboard

Ensures fuel can’t be collected anywhere and drip on engine

54
Q

What is a direct drain system?

A

Drain lines which end with a specific hole in the drain mast.
(Fuel lines on left, oil lines on right)

55
Q

How can you identify which system a leak has come from on a direct drain system?

A

Follow the fluid mark directly to the designated hole.(tells you which system it’s from)

56
Q

How do you do a system leak rate check on the drain systems?

A

Disconnect drain lines from the drain mast and fit small plastic bottles to it. Do engine leakage run

57
Q

What is the purpose of a drain collector system?

A

Uses separate collectors to catch leaks for individual accessory gear box components

58
Q

On drain collector assemblies, where do leaks which aren’t from the accessory gear box go?

A

Directly to the drain module assembly.

59
Q

What is the system process if there is a leak in the fuel pump?

A
  1. Fuel pump collector
  2. If full overflows to holding tank
  3. Overflow again, to drain mast
60
Q

Why should an overflow of the holding tank not occur?

A

As it is emptied during flight

61
Q

How are holding tanks emptied during flight?

A

Ram air enters front side of drain mast, at 200 knots ram air pressure opens spring loaded valve and pressurises tank
(Fluid forced out)

62
Q

How do you empty collectors?

A

Manually by a spring loaded drain valve

Used to check leakage rate of accessory drive seal

63
Q

How do you check the leakage rate of an accessory drive seal?

A

Drain collectors with manual spring loaded drain valve. Measure fluid. Next flight compare the fluid leakage against collected fluid.

M15 (18 decks)

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