Hydraulic Ata Ch 24

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Hydraulic Power Basics

Hydraulic fluid

Components

System type


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Hydraulic fluid

Low freezing point

minimum viscosity change withtemperature variations

good lubrication quality

high flash point anti-corrosive quality

minimum effect on rubber based seals and

lines


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Hydraulic fluidTYPE DYED

COLORSEALS & HOSES USAGE

VEGETABLE NO PURE RUBER Light A/C brake

MINERAL RED NOT NATURE

RUBBER

BRAKE, HYD,

LANDING GEAR

SYNTHETIC GREEN,PURPLE,

AMBER

BUTYL-RUBBER,

ETHYLENE,

PROPYLENE,TEFLON

LARGE A/C


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Components

Pump

Pipe-line , Hoses Reservoir

Accumulator

Motor Valve

Actuator

Filter


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Hydraulic Pipeline


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Hydraulic Reservoir


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Hydraulic Motor


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System type - Open vs Close
http://www.engineersedge.com/hydraulic/open_center_system.htmhttp://www.engineersedge.com/hydraulic/fixed_displacment_closed_center_system.htmhttp://www.engineersedge.com/hydraulic/fixed_displacment_closed_center_system.htmhttp://www.engineersedge.com/hydraulic/open_center_system.htm


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ATA 29 Hydraulic Power

GeneralThe hydraulic power is used to operate high power

demand services :

Flight controls ATA 27

Landing gear and braking system ATA 32 Cargo compartment doors ATA 52

Electrical Power (CSM/G) ATA 24

Thrust reversers ATA 78

The system is consists of :

MAIN HYDRAULIC SYSTEMS (29-10)

AUXILIARY HYDRAULIC SYSTEMS (29-20)

HYDRAULIC INDICATING SYSTEM (29-30)


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29-10 MAIN HYDRAULIC SYSTEMS The main hydraulic power systems are those which

supply the high power consumers of the aircraft with

hydraulic power. The aircraft has multiple main

independent hydraulic systems.

The systems are hydraulically isolated from each other.

It is not possible for hydraulic fluid to go from one

system to any other system.


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29-10 MAIN HYDRAULIC SYSTEMS Each system includes:

A reservoir to supply the hydraulic fluid to the pump and to

collect fluid from the return line.

Hydraulic reservoir pressurization system. The aircraft has a

pressurization system for the hydraulic reservoirs. Eachreservoir gets pressurized air to 45~65 psia(usual operation in

flight or on ground), which prevents cavitation of the pumps,

maintains normal return pressure in the hydraulic system, and

also helps to prevent foaming in the reservoirs. The system

also remains airtight in the event of failure of the pressurizationsystem or after an engine shutdown.

One (or two) engine pump(s) directly connected through the

accessory gearbox.


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29-10 MAIN HYDRAULIC SYSTEMS Each system includes(cont) :

The engine pump pressurizes automatically the hydraulic

system in a few seconds at a nominal pressure of 3000 PSI

(206 bars) when the relevant engine operates.

A fire shut off valve installed on the suction line of each enginepump and which isolates the pump from the reservoir in case of

fire or suction line rupture, or engine burst failure affecting at

least two hydraulic systems.

A HP manifold which directs pressure to all the user systems

and on which are installed: pressure switches

a pressure transducer

a relief valve

a leakage measurement solenoid valve.


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A ground service manifold to isolate on ground each section of

the system for the internal leakage measurement.

A system accumulator to damp pressure surges and

compensate pump response time in the event of high outputdemand.

Valves (check valves - priority valves, pressure-relief valves,

selector valves) which govern the possibility, direction or

priority of fluid flow.

Filters, which maintain cleanliness of the fluid.

Return manifolds.


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It is also possible to pressurize each main system with one or

more of the auxiliary systems if the main pumps cannot be

used or if for maintenance, a ground power cart is not available.

For maintenance all the systems can also be pressurized froma ground power cart. Connectors are installed on the ground

service panels of the systems.


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29-20 AUXILIARY HYDRAULIC SYSTEMS The auxiliary hydraulic systems supply alternative

pressure sources to hydraulic systems in case of total

engine failure.

These are the auxiliary hydraulic systems: Electric hydraulic pump.

Hydraulic power transfer unit (PTU).

Ram Air Turbine(RAT).


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RAT


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29-30 HYDRAULIC INDICATIONSYSTEMS

The hydraulic systems have sensors which monitor the

condition of the systems. The sensors monitor:

the contents of the hydraulic fluid in the reservoirs

the pressure of the hydraulic fluid in the systems

the output pressure of the pumps

the temperature of the hydraulic fluid (reservoir, electrical pump)

the internal pressure of the reservoir

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Hydraulic Ata Ch 24