Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Groundschool : Module 1 > AGK Systems - Hydraulic Systems > Flashcards

AGK Systems - Hydraulic Systems Flashcards

1
Q

What are actuators?

A

Turn hydraulic pressure into movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Three types of linear Actuator

A

Single Acting
~hydraulic pressure in one direction against a spring

Double Acting Balanced
~Selectable equal hydraulic pressure in both directions but equal force

Double Acting (Unbalanced)
~Selectable equal hydraulic pressure in both directions but unequal force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are Selector Valves?

A

Direct hydraulic fluid to various parts of the system

Amongst other things they can control the direction of their movement

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

Selector Valve Types

A

Closed Centre Selector

Open Centre Selector

Linear Valve Selector

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

Open Centre Hydraulic Systems

A

Only one actuator can be used at any one time

Small to mid sized a/c

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Closed Centre Hydraulic Systems

A

Maintains constant supply of hydraulic fluid pressure using a Variable Volume Pump

Services supplied in parallel so can be operated simultaneously

Off loading valve allows pump to unload when services are not operated
~reduces engine power required

Multiple actuators can be moved at the same time

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Light A/C systems

A

Uses self containing hydraulic power pack via reversible DC electric motor

Gear is held in retraced position by hydraulic lock

Pump comes on line when required

Thermal relief valve protects against over pressure

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is a Hydraulic Reservoir?

A

Stores hydraulic fluid

Allows for thermal expansion of hydraulic fluid

Accepts fluid retaining from low pressure side of hydraulic system

Holds excess fluid to compensate for leaks

They are pressurised to stop boiling at alt

Sight Glass to check the level

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What are stack pipes?

A

Keep a level of fluid in them in case of an emergency

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is an accumulator?

A

Comprises pressurised gas and fluid in a cylinder separated by a piston or rubber diaphragm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Accumulator uses

A

Provide emergency braking system
~6 applications of brake

Used to damp out pressure pulses

Cater for thermal expansion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

An Accumulator pressure gauge displays…

A

Pre charge nitrogen gas pressure the hydraulic system isn’t provided

Hydraulic System pressure when it is powered

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What happens if you incorrectly pre charge an Accumulator?

A

harmful hammering

E.g. Hydraulic Leak

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

Accumulator Summary

A

Stores energy to keep hydraulic fluid under pressure

Provides limited supply of pressure in an emergency

Dampens out pressure fluctuations

Allows for thermal expansion

Cater for small internal leaks

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Hydraulic Pumps

A

Provide fluid flow and therefore pressure, they do not provide pressure

Usually EDP’s

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are two widely used Hydraulic pumps?

A

Constant Delivery (fixed volume) Pump
~these are spur and rotary pumps often in light a/c

Constant Pressure (variable volume) Pump
~These piston pumps more common in larger a/c (around 3000psi)

17
Q

Constant Delivery (fixed volume) Pump

A

Provides constant fluid supply

Typically spur gear

Flow rate dependant on speed of rotation

Gears normally rotate at constant speed

REQUIRES AN AUTOMATIC CUT OUT VALVE (ACOV)

18
Q

Constant Pressure (variable volume) Pump

A

Output volume NOT dependent upon pump RPM

Volume CAN be altered

Self Regulates and only supplies fluid needed to maintain constant woking pressure

Engine Driven

On start up: pump swash plate is at maximum deflection

Pump is lubricated by hydraulic fluid

DOES NOT require ACOV

19
Q

When is the Constant Pressure Pump at nil stroke?

A

When swash plate is perpendicular to input drive shaft

20
Q

What is a case drain?

A

Keeps pump cool when not pumping as it may get very hot

21
Q

What is a hydraulic motor?

A

Uses hydraulic pressure to generate rotary motion

Forces piston down in cylinder block

Useful for operating screw jacks to drive the flap and slat mechanisms

Speed of motor is dependant on fluid flow rate

Selector Valve can change direction of rotation

22
Q

What does a Pressure Relief Valve do?

A

Protects system from over pressurisation

May act as a Thermal Relief Valve (TRV)

23
Q

What is a Restrictor Valve?

A

Reduces fluid flow to slow the speed of operation of a service

A one way restrictor allows full flow in one direction and restricted flow in the other

E.g. slowing of landing gear extension

24
Q

What is a Priority Valve?

A

Ensure sufficient fluid flow at all times to the primary controls and wheel brakes

It closes and isolates non essential circuits if system pressure drops below a set limit

25
Q

What is a shuttle valve

A

Allows most appropriate pressure

Allows one service to be operated by two independent supplies

guarantees an adequate supply if either system fails

Under normal operating conditions the shuttle is to the left side

When the main supply fails the shuttle moves to the right and allows the emergency supply to take over

26
Q

What is a hydraulic Fuse?

A

Upstream of components to shut off flow & prevent total fluid loss in the event of a major leak

Shuts off when there is a leak in the system by the difference in pressure - where the leak is
~Results in no fluid loss

27
Q

What is a Shut Off Valve?

A

Similar to Hydraulic Fuses

They’re not self regulating

Operate by external controller
~E.g. control on FD

28
Q

Large A/C Hydraulic System Schematic

A
29
Q

What is a Hand pump?

A

Used for maintenance or emergency back up

Used on the ground to operate hydraulic doors, brakes, flaps and anything linked to that system

Hydraulic fluid is supplied from the bottom of the Reservoir

30
Q

RAT

A

After landing, probably need a tug as it doesn’t provide any hydraulic power after landing due to the speed of the a/c

ONLY PROVIDES HYDRAULIC POWER FOR FLIGHT CONTROLS

31
Q

Hydraulic Power Transfer Unit (PTU)

A

On modern a/c with more than one hydraulic system, back up power can be obtained via a PTU

Concept of PTU:
~hydraulic motor in one system
~drive hydraulic pump on another system

32
Q

Air Turbine Motors (ATM)

A

High pressure bleed air from an engine powers an air turbine which in turn, powers an hydraulic pump

Used on older a/c designs

33
Q
A

Groundschool : Module 1 (38 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions