The motoring valve lever controls the motoring valve. When you hold the lever in the MOTOR position, center hydraulic system pressure goes to the inlet side of the RAT hydraulic pump. This causes the pump to operate as a motor and turns the turbine.
The RAT governor controls the RAT speed to the normal RAT RPM.
The RAT requires a minimum of 45 gpm flow in the center hydraulic system to operate the RAT at full speed.
The ELMS calculates RAT speed from the RAT generator frequency. The hydraulic maintenance page shows RAT speed.
Training Information Point
When you release the motoring valve lever, the RAT motoring valve goes back to the FLIGHT position. The RAT then becomes a pump as it slows down. This pressurizes the hydraulic fluid to the RAT pressure transducer and turns on the RAT PRESS light. The RAT pressure indication stays on until internal leakage in the RAT module causes the pressure to decrease.
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RAM AIR TURBINE SYSTEM -FUNCTIONAL DESCRIPTION -MOTORING
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RAM AIR TURBINE SYSTEM -RAT GENERATOR HEATER SYSTEM
General
The RAT generator heater system operates automatically to heat the RAT generator. This prevents icing in the generator that could prevent RAT spin-up at low airspeed. The icing could be caused by moisture that gets into the RAT generator through many humid air/cold air cycles during normal airplane operation.
There are two heater elements in the generator. Only one element operates at a time. The other element is a spare.
The HYDIM CL card controls the RAT generator heater system. The P210 right power management panel supplies the electrical power to operate the heater system.
Functional Description
The HYDIM CL card sends a signal to the ELMS to operate the RAT heater for any of these conditions:
*
Total air temperature is less than 36F (2C) (ADIRU input through the AIMS)
*
ADP C1 case drain temperature is less than 77F (10C)
*
ADP C2 case drain temperature is less than 77F (10C)
*
ADP C1 operational test (MAT test)
*
ADP C2 operational test (MAT test)
*
Heaters operational test (MAT test).
The ON signal goes to the ELMS electronics unit (EEU) in the P210 power management panel. The EEU energizes relays to supply power to the RAT heater and to the ADU heaters.
The heaters go off 30 minutes after the total air temperature increases to more than 36F (2C) and both ADP case drain temperatures are more than 77F (10C). The heaters also go off 5 seconds after a RAT deployment.
A current monitor in the ELMS sends heater operation feedback to the EEU. The EEU sends this data to HYDIM CL to find RAT heater faults.
Indication
There is no indication that the RAT generator heater system is on. A RAT GEN HEAT status message shows for these conditions:
*
RAT generator heat is not on when commanded on
*
RAT generator heat is on when not commanded on.
Training Information Point
If one of the RAT heater elements fails, you can select the other element with the RAT generator heater switch on the E6-2 shelf.
You can do a test of the operation of the RAT generator heater system with a ground test through the MAT.
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RAM AIR TURBINE SYSTEM -RAT GENERATOR HEATER SYSTEM
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777 AIRCRAFT MAINTENANCE MANUAL
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HYDRAULIC INDICATING SYSTEM -INTRODUCTION
General
The hydraulic indicating system monitors these values:
*
Fluid and reservoir pressures
*
Fluid temperature
*
Fluid quantity.
The indicating systems get input from these sensors:
*
Hydraulic pump pressure transducer (8)
*
Hydraulic system pressure transducer (3)
*
Hydraulic reservoir pressure switch (3)
*
Hydraulic pump temperature transducer (8)
BEJ ALL POST SB 777-29-0024
* ACMP temperature switch (4)
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*
Hydraulic reservoir temperature transducer (3)
*
Hydraulic reservoir quantity transmitter (3)
Interface
The indicating systems sensors send data to the HYDIM cards. The HYDIM cards send the data to the AIMS for flight deck indication. The HYDIM cards also control the fault lights and the RAT indication lights on the hydraulic/RAT panel. 中国航空网 www.aero.cn 航空翻译 www.aviation.cn 本文链接地址：777 AMM 飞机维护手册 液压 Hydraulic Power(26)
