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29-00-00
ALL ú ú 01 Page 1 ú Jun 15/98
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
D. Ground service connections are given at each of the pressure and return modules. The ground service connections allow you to attach an external hydraulic supply source. Each hydraulic supply system reservoir can be filled from a central fill valve found in the left body gear wheel well. To fill the reservoirs, it is necessary to use an airplane-installed hand pump, or an external pressure filling cart. The ground servicing system is described in 29-18-00.
E. Hydraulic systems 1 and 4 are used to supply power for these:
-all landing gear systems
-normal and alternate brake systems
-trailing edge flaps
-
some of the primary flight controls (ailerons, elevators, and rudder) for the redundancy that is necessary.
F.
Each system (1 through 4) supplies power for the thrust reverser
operation of the related engine.
G.
Hydraulic systems 2 and 3 are used to supply power for most of the primary flight controls. System 2 supplies power for the alternate brakes.
3. Indicating and Warning Systems
______________________________
A. Signals given by sensors, transmitters, and switches are supplied to the hydraulic interface module (HYDIM) or the Hydraulic Quantity Interface Module (HYQUIM). The HYDIM and HYQUIM give outputs to the EICAS Interface Unit (EIU), hydraulic pumps, and the hydraulic control panel. The EIU gives signals to the EICAS display and the Central Maintenance Computer (CMC). Pressure/low pressure, temperatures, and quantity/low quantity are shown on the overhead panel and/or on the Engine Indicating and Crew Alerting System (EICAS), and/or on the CMC.
B. The hydraulic systems panels on the pilot's overhead panel has an amber light (SYS FAULT) for each hydraulic system. The light comes on when there is one or more of the following:
-
System low pressure
-
System low quantity
-
System overheat. The panel also has lights (PRESS) to show low pressure for each individual pump.
C.
Hydraulic Low Pressure Warning System
(1)
The hydraulic low pressure warning system gives a visual warning when the pressure in any of the hydraulic pumps, or the system pressure becomes too low. The hydraulic control module is found on the P5 panel in the flight compartment. The module has a PRESS light for each of the four engine-driven pumps (EDP's) and the four demand pumps. There is also a SYS FAULT light on the hydraulic control module for each hydraulic system.
D.
Hydraulic Fluid Quantity Indicating System
(1)
The hydraulic fluid quantity indicating system gives a visual display of the quantity of fluid in each hydraulic system. The indication is given as a fraction of the total system capacity. The indicating system will also give a visual warning if the fluid quantity becomes too low.
EFFECTIVITYùùùùùùùùùùùùùùùùùùùùùùùùùùùùùù. ú
29-00-00
ALL ú ú 05 Page 2 ú Jun 10/96
BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400
MAINTENANCE MANUAL
(2)
The hydraulic fluid quantity indicating system has a hydraulic fluid quantity transmitter for each hydraulic system. The Hydraulic Quantity Interface Module (HYQUIM) gives an output to the hydraulic control panel. The panel will show a warning when the fluid quantity decreases to 34 % of the system capacity. The quantity of fluid in each system is shown on the EICAS HYD page.
(3)
Since there is standpipe at the bottom of the reservior, the quantities of fluid not accessible to indication (the fluid level in EICAS reading is zero) are 1.12 gallons for system 1 and 4 and 0.74 gallons for system 2 and 3.
E.
Hydraulic Fluid System Overheat
(1)
The hydraulic fluid system overheat warning system gives a visual warning if the temperature of any of the hydraulic systems becomes too high. The warning system also shows the actual value of the temperature of each hydraulic system.
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