Airbus A350 - Hydraulic System
Each hydraulic system is monitored and controlled by its associated Hydraulic Monitor & Control (HMC). The normal operating pressure of each hydraulic system is approximately _____
The reservoir is self-pressurized to prevent pump cavitation, and incorporates an automatic bleed device that removes entrapped air on ground only.
Each hydraulic system has its own cooling system, that prevents the overheat and thermal degradation of hydraulic fluid. Each hydraulic system has one hydraulic heat exchanger in:
The temperature of the fluid is controlled by a temperature control valve inside the case-drain filter manifold.
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If either system fails, the steering remains available because of:
In the case of one or both hydraulic systems fail, the following backups are available:
If only one engine-driven pump per hydraulic system is operative, the following systems remain available:
Landing gear retraction/extension is available but retraction time is longer than in normal.
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The GREEN and YELLOW pumps can only be disconnected via maintenance action on ground.
There is one fire shutoff valve (FSOV) per engine (one FSOV per engine driven pump). The fire shutoff valve is between the reservoir and the engine-driven pump.
There are two fire shutoff valves (FSOVs) per engine, one FSOV per engine driven pump. The fire shutoff valves are between the reservoir and each engine-driven pump.
In the case of excessive temperature, overheat, low pressure or low level in the hydraulic system, the Hydraulic Monitoring and Control Application (HMCA) automatically stops the operation of the affected electric pump as long as the hydraulic failure is present.
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The electric pump reinflates the accumulator to ensure a sufficient pressure:
There is one electric pump per hydraulic system which can provide hydraulic power only on ground (when all engines are off) and in flight.
There is one electric pump per hydraulic system which can provide hydraulic power only on ground, when all engines are off. The electric pump is powered with 230 V at a fixed frequency of 400 Hz. Due to the variable frequency of the engine generators, the electric pump is inhibited as soon as one engine is started.
An accumulator helps to maintain a constant delivery pressure to the consumers and compensates for transient demands during:
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EXCESSIVE TEMPERATURE IN THE HYDRAULIC SYSTEM - The hydraulic system monitors the temperature in the reservoir and in the EDP. If the abnormal temperature is detected in the RSVR, both EDPs are automatically depressurized and the associated hydraulic system is lost until the end of the flight.
The aircraft has two identical and independent hydraulic systems, referred to as GREEN and YELLOW. These two systems operate continuously, and power:
A FSOV (fire shutoff valve) close automatically, when:
When the EDP case drain overheat is detected, the system shuts down automatically, associated with the HYD G(Y) SYS PRESS LO ECAM alert.
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