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MAIN HYDRAULIC SYSTEMS -TRAINING INFORMATION POINTS -GROUND SERVICING SYSTEM
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BOEING PROPRIETARY -Copyright # -Unpublished Work -See title page for details.
RAM AIR TURBINE SYSTEM -INTRODUCTION
General
The ram air turbine (RAT) supplies an emergency source of hydraulic power to operate the flight controls. The RAT also is an emergency source of electrical power.
The RAT extends automatically in flight with a loss of hydraulic pressure in the three hydraulic systems. You can manually extend the RAT from the flight deck.
Control of RAT retraction is from the right wheel well.
Components
These are the components of the ram air turbine system:
*
RAT assembly
*
RAT actuator
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RAT compartment door and actuation link
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RAT stowed switch (not shown)
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RAT checkout module.
Most RAT components are in the RAT compartment behind the right wheel well. The RAT checkout module is in the right wheel well.
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RAM AIR TURBINE SYSTEM -INTRODUCTION
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RAM AIR TURBINE SYSTEM -GENERAL DESCRIPTION
General
The HYDIM cards or the ELMS control the automatic operation of the RAT.
The RAT manual switch permits manual RAT extension. Indication lights on the RAT manual switch show RAT pressure indication and RAT unlocked condition.
HYDIM Control
The two center HYDIM cards get these inputs to control automatic RAT extension:
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Airspeed (ADIRU through the AIMS)
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Groundspeed (ADIRU through the AIMS)
*
Air/ground condition (WOW cards)
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Engines above idle (EDIUs)
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Hydraulic system pressures (HYDIM).
RAT Power Output
The RAT hydraulic pump supplies hydraulic power for some of the center hydraulic system flight controls.
The RAT generator supplies electrical power to the P310 standby power management panel in the ELMS. See the standby power section for more information about the RAT generator (SECTION 24-33).
Indications
The AIMS gets RAT position and pressure data for flight deck indication and fault detection.
RAT pressure indication shows on the hydraulic synoptic display, the hydraulic maintenance page, and the pressure light on the RAT manual switch.
The ELMS calculates RAT speed from the RAT generator frequency. RAT speed shows on the hydraulic maintenance page.
RAT Generator Heater System
A RAT generator heater system keeps moisture from freezing inside the RAT generator. Ice inside the generator could stop RAT spin-up if the RAT is deployed at low airspeeds.
HYDIM controls the RAT generator heater system. The ELMS supplies the electrical power to operate the heaters.
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RAM AIR TURBINE SYSTEM -GENERAL DESCRIPTION
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RAM AIR TURBINE SYSTEM -RAT ASSEMBLY
General
These components are part of the RAT assembly:
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RAT governor-generator assembly
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RAT hydraulic pump
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RAT strut
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RAT blade lock pin
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RAT blade locked switch
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RAT strut angle switch.
RAT Governor-Generator Assembly
The RAT governor-generator assembly has these components:
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Turbine
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Flyweight governor
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Electric generator.
A two-bladed variable pitch turbine turns the shaft of the generator and the pump. Turbine blade diameter is approximately 41.5 inches (105 cm).
The flyweight governor is inside the turbine hub. It controls turbine blade pitch to control turbine speed. Governed speed is approximately 4510 rpm.
The generator is a 115v ac, 3-phase generator rated at 7.5 KVA. A RAT generator heater system keeps ice out of the generator. See the standby power section for more information about the RAT generator (SECTION 24-33).
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