Blue Auxiliary Hydraulic Power

ATA29
  • The Blue auxiliary hydraulic power system supplies hydraulic power from the ram air turbine (RAT) to the Blue main hydraulic power system.
  • The RAT produces also electrical power through the constant speed motor/generator (CSM/G).
  • The actuator extends the RAT into the airflow automatically when there is:
    • A failure of both engines, or
    • A failure of one engine together with a failure of the electrical generator of the other engine
    • A total AC failure.
    • Note : The automatic function only operates when the speed of the aircraft is more than 100 kts ( 185 km/h)
  • Final : tóm lại vì 1 lý do gì đó khiến cho cả 2 nguồn AC fail và vận tốc máy bay nhiều hơn 185km/h ( 100 kts).thì nó sẽ tự động extend.
  • The flight and maintenance crews can also extend the RAT from the flight compartment. It is only possible to retract the RAT when the aircraft is on the ground.
  • The RAT has a stall protection device which prevents a RAT stall below the governed speed range. The stall protection device limits the maximum power the pump can take from the turbine. When the stall protection device is in operation, the pump displacement is adjusted to get a constant RAT speed not related to the aircraft speed.
  • The main components of the Blue auxiliary system are:
    • The RAT
    • The leg assembly with its pivot
    • The hydraulic pump
    • The RAT Actuator
    • The RAT control panel and
    • Selector switches to extend the RAT from the flight compartment.
  • The drain port of the RAT gearbox has a leakage drain line which transfers hydraulic fluid from the internal reservoir of the RAT pump to an external drain tank. The location of the drain tank is behind a cover plate on the left side of the RAT bay.
  • A P/BSW (2805GE) is installed on the hydraulic control panel 40VU in the cockpit. This switch permits the pilot to manually select the deployment of the RAT.
  • An index mechanism installed on the front of the leg assembly locks the turbine hub assembly in the correct position. The turbine hub has markings which allows easy alignment between the turbine hub and the index mechanism. This then permits the RAT to be stowed. During the deployment of the RAT, the index mechanism disengages from the turbine hub when the leg is not more than 10 deg before full extension
  • The RAT actuator extends the RAT into the airflow with the force of a spring. Therefore no hydraulic power is necessary to extend the RAT.
  • Two solenoids and one proximity switch are installed on the top of the RAT actuator. The two solenoids release a lock and the RAT extends. The RAT extends when both or one solenoid is energized. An extend lock keeps the RAT in the extended position.
  • A stow proximity switch gives a signal to the ECAM system if the RAT actuator is extended. The stowed proximity sensor sends a signal to the RAT control panel and the indicator light RAT STOWED comes on when the RAT is locked in its retracted position.
  • The RAT control panel has:
    • an ON/OFF switch to switch off 28 V DC,
    • a STOW/RESET switch,
    • a residual pressure warning light,
    • a RAT stow indicator light,
    • an interlock warning light,
    • a lamp test switch,
    • a ground connector.
  • The extension of the RAT is controlled by the:
    • Manual operation of the pushbutton switch OVRD HYD 2805GE on the HYD section of the overhead panel 40VU, or
    • Manual operation of the pushbutton switch OVRD ELEC 24XE on the overhead panel 21VU, or
    • Automatic control in the event of a total failure of the AC busbars 1XP and 2XP.
  • When the RAT receives an automatic or manual command to extend, one of the two deploy solenoids operates and releases the internal lock. Spring pressure causes the RAT actuator to extend, which extends the RAT into the airflow.
  • When the RAT extends, the stowed switch operates and sends a signal to the ECAM system where the legend RAT OUT appears.
  • Final :
    • có 2 solenoid phụ trách việc extend RAT , chỉ cần 1 trong 2 solenoid được energize là sẽ extend được RAT.
    • Có 1 stow proximity switch gửi tín hiệu đến ECAM báo RAT OUT. Đồng thời trên RAT Control Panel sẽ có indicator light RAT STOWED sáng.
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