AGK systems Lesson 2 Flashcards

1
Q

Input force x input distance =

A

output force x output distance

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2
Q

A Smaller piston displaces a volume equal to area multiplied by?

A

the distance moved (its stroke)​

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3
Q

Force =

A

area x pressure

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4
Q

area x pressure =

A

force

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5
Q

Passive hydraulic systems use _____ _____ to raise pressure

A

Passive hydraulic systems use human power to raise pressure

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6
Q

Active hydraulic systems use one or more _____

A

pumps​

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7
Q

Closed centered systems​ provides

A

Constant pressure all the time

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7
Q

Active systems can supply:​

A

Constant pressure all the time - closed centered systems​

Pressure only when demanded - open centered systems.​

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8
Q

Open centered systems provides

A

Pressure only when demanded -

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9
Q

What fulid do we put into an aircraft system?

A

Correct specification from an unopened container.

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10
Q

Hydraulic fluid must have these properties:​

A

Low viscosity to allow it to flow freely through the system​

Resistance to foaming or creating sludge​

Good lubrication qualities ​

Corrosion resistance​

Resistance to heat and thermal stability across the temperature range​

High boiling point and low freezing point (e.g., +80°C to -70°C)​

Chemically inert​

Non-flammable with a flash point above 100°C​

Good storage properties.

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11
Q

Hydraulic fluid is available in two common forms:​

A

Synthetic
Hydro-carbon based - Used in systems with butyl rubber/Teflon seals – may be Orange in colour​

Phosphate Ester (Synthetic) – Skydrol – usually purple in colour​

Mineral
For example DTD 585 which is coloured red​

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12
Q

Hydraulic fluids can be very _________ so avoid contact and wear protective clothing

A

corrosive

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13
Q

Which hydraulic fluid​ is red?

A

Mineral Based​
Kerosene​
Red​
Suitable for high pressure systems​
Good resistance to foaming​
High Boil and Flash Point although flammable​
Synthetic rubber seals

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14
Q

Which hydraulic fluid​ is purple?

A

Synthetic Based​
Phosphate Ester​
500A purple in colour​
Skydrol​
3 Grades in use​
500 500A 700​
Can be used at very high pressures​
Must only be used with the following:​
Butyl Rubber Ethylene Propylene ​
Teflon seals

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15
Q

Advantages of Hydraulic Systems

A

Excellent for providing large amounts of power​

Very little energy is lost in the transmission process​

Other advantages include:​

> Leaks are relatively easy to spot​
Reduced weight when compared to mechanical system​
Provide large amounts of force to operate heavy services.​

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16
Q

Disadvantages Hydraulic System

A

The fluid is highly corrosive​

The forces generated can require strong structures​

Large systems can be quite heavy​

Susceptible to fluid contamination​

Damage to hydraulic lines​

Hydraulic fluid is health risk and environmentally hazardous.​

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17
Q

What are the basic components of a hydraulic system

A

Reservoir
Accumulator
Pump
Double acting cylinder
Non return valves
4 port rotary selector valve

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18
Q

What is the operating range of a hydraulic system?

A

3000 - 4000psi

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19
Q

Does a hydraulic cylinder provide the same force in both directions?

A

No, the area is different in each direction due to the rod coming out of the system

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20
Q

Reasons for hydraulic pump failure

A

Electrics
Engine
No fluid

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21
Q

What does an actuator do?

A

Convert hydraulic pressure into movement

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22
Q

What’s the difference between single and double acting hydraulic actuators?

A

Single is pushing against a spring and has one feed.

Double has a double feed, the fluid pushes the piston in each direction?

23
Q

What are the types of selector valves?

A

Closed centre selector
Open centre selector
Linear (spool) valve selector

24
Q

There are two fundamental types of system:​

A

Passive - No hydraulic pump​
Active - Mechanically driven pump.​

25
Q

Most ‘transport category’ aircraft have what type of hydraulic system?

A

Closed centre system

26
Q

Describe the type of system that’s likely to be seen in a king air?

A

Uses a self-contained hydraulic power pack, operated by a reversible DC electric motor

27
Q

Which two liquid storage systems would need pressurising?

A

Hydraulic fluid
Fuel

28
Q

Describe the hydraulic system

A

Stores the hydraulic fluid sufficient for all actuators at full extension​

Normally pressurised but may be vented to atmosphere​

It allows for fluid thermal expansion and replenishment of system loss​

Accepts fluid returning from the low pressure side, usually after cooling​

Holds excess fluid to compensate for leaks​

Has a sight glass to check the level when:​

All system components are at the correct setting​

Accumulators are fully charged.

29
Q

Half atmospheric pressure is at what altitude?

A

18,000ft

30
Q

Why use a pressurised reservoir?

A

Prevents the fluid from boiling at altitude​

Provides positive pressure at the pump inlet

31
Q

Which gas is used in a Hydraulic accumulators?

A

Nitrogen

32
Q

EDP is a shortening of

A

Engine driven pump

33
Q

Hydraulic pumps may be pressurised by:

A

Engine driven​
Electrical motor driven​
Hand operated​
Driven by a Ram Air Turbine (RAT)​
Driven by a hydraulic motor or Power Transfer Unit (PTU)​

34
Q

Hydraulic pump may break mechanically. How is the accessory gearbox protected from this?

A

Quill Drive (illustrated) provides a weak ‘shear’ link. In the event of pump seizure the quill drive shears and disconnects – protects the driveline and engine.​

35
Q

Constant Delivery Pump

A

Constant delivery or fixed volume pump provides fluid​

Typically spur gear system​

Flow rate dependent on speed of rotation of the gears​

Normally requires an automatic cut out valve (ACOV).​

36
Q

Constant delivery pump is always paired with an

A

automatic cut-out value

37
Q

An automatic cut-out valve is always paired with a

A

constant delivery pump

38
Q

What type of pump is based on a swash plate and provides a constant pressure. It only demands power when pressure is being demanded.

A

Swash-plate pump
Multiple piston pump

39
Q

The swash-plate pump is at nil stroke at what point?

A

When the swash plate is perpendicular to the shaft

40
Q

A Swash-plate pump may get hot in low demand situations. How is this rectified?

A

A case drain will allow a calibrated amount of hydraulic fluid can escape and return to the reservoir.

41
Q

What type of pump does the following describe?

Pump output is not dependent on speed​

Output volume is regulated by the control piston​

No ACOV or accumulator required​

Driven by a gearbox linked to the engine​

On start up:​

The pump swash plate is at minimum deflection = 0° (upright) ​

A blocking valve off-loads the pump – recirculates oil inside the pump – pressure to suction​

The pump is lubricated by the hydraulic fluid.​

A

Constant pressure pumps

42
Q

Hydraulic motors are like another component in reverse?

A

Swash-plate pump

43
Q

Tell me about hydraulic filters

A

Micron type filters used using a pleated element with a shape retaining spring​

​The element is designed to capture contaminants greater than 10 microns diameter​

44
Q

What happens if the filter gets blocked?

A

If the filter begins to clog:​

Differential pressure sensor operates warning light​

Or a red filter pop-out button protrudes from main casing​

A bypass valve automatically allows unfiltered fluid to flow.​

45
Q

What does a restrictor valve (choke valve) do?

A

Slows flow in one direction.

46
Q

What does a shuttle valve do?

A

Selects between two independent supplies

47
Q

Aircraft tyres have a carbon content to do what?

A

Earth the aircraft

48
Q

Oleo contains:

A

Nitrogen and oil

49
Q

What does the oil in an oleo control

A

compression and extension

50
Q

In an oleo, what is the spring medium

A

nitrogen

51
Q

In an oleo, what is the medium used for dampening.

A

Hydraulic oil
DTD 585

52
Q

What type of switches are used for weight-on-wheels and landing gear?

A

Microswitches
or
proximity switches

53
Q

When is an undercarriage leg is subject to the greatest tortional load?

A

the strut on the inside of a tight turn

54
Q

VLO stands for

A

Velocity Landing Gear Operating (Travelling (doors open)

55
Q

VLE stands for

A

Velocity Landing Gear Extended (Down (doors closed)

VLE is higher for ferry flights

Beware of fuel consumption

56
Q
A