Hydraulic Power Basics

1
Hydraulic Power Basics

• Hydraulic fluid
• Components
• System type

2
Hydraulic Power Basics

• Hydraulic fluid
• Low freezing point
• minimum viscosity change with temperature
  variations
• good lubrication quality
• high flash point
• anti-corrosive quality
• minimum effect on rubber based seals and lines

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Hydraulic Power Basics

• Hydraulic fluid

4
Hydraulic Power Basics

• Components
• Pump
• Pipe-line , Hoses
• Reservoir
• Accumulator
• Motor
• Valve
• Actuator
• Filter

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Hydraulic Pump
Fixed Volume Pump
Variable Volume Pump
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Hydraulic Pipeline
7
Hydraulic Reservoir
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Hydraulic Motor
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Hydraulic Power Basics

• System type - Open vs Close

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ATA 29 Hydraulic Power

• General
• The 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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ATA 29 Hydraulic Power

• 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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ATA 29 Hydraulic Power

• 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. Each reservoir gets
  pressurized air to 4565 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
  pressurization system or after an engine
  shutdown.
• One (or two) engine pump(s) directly connected
  through the accessory gearbox.

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ATA 29 Hydraulic Power

• 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 engine pump 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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ATA 29 Hydraulic Power

• 29-10 MAIN HYDRAULIC SYSTEMS
• Each system includes(cont)
• 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 output demand.
• 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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ATA 29 Hydraulic Power

• 29-10 MAIN HYDRAULIC SYSTEMS
• Each system includes(cont)
• 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 from a ground power cart. Connectors
  are installed on the ground service panels of the
  systems.

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ATA 29 Hydraulic Power

• 29-10 MAIN HYDRAULIC SYSTEMS

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ATA 29 Hydraulic Power

• 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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ATA 29 Hydraulic Power

• RAT

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ATA 29 Hydraulic Power

• 29-30 HYDRAULIC INDICATION SYSTEMS
• 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