747-400 AMM 飞机维护手册液压 HYDRAULIC 2(119)_航空信息_民用航空_通用航空

(12)
If you find leakage, repair the cause of the leakage.

S 864-019

(13)
Release the pressure in the hydraulic system if it is not necessary (Ref 29-11-00/201).

S 864-020

(14)
Remove the electrical power if it not necessary (AMM 24-22-00/201).

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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
A
747-400 MAINTENANCE MANUAL
S 214-021
(15)
Examine the doors on the trailing edge fairing:

(a)
Examine the latches on the doors in the trailing edge fairing for cracks and wear.

(b)
Make sure all the latches are there.

S 414-022
CAUTION: MAKE SURE YOU LATCH THE DOORS ON THE TRAILING EDGE FAIRING
_______ CORRECTLY. IF THE DOORS OPEN DURING A FLIGHT, THIS CAN CAUSE DAMAGE TO THE DOORS
(16) Close the doors in the trailing edge fairing (AMM 54-62-00/201).
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BOEING PROPRIETARY - Copyright (C) - Unpublished Work - See title page for details.
1.

A
747-400 MAINTENANCE MANUAL
HYDRAULIC FLUID QUANTITY INDICATING SYSTEM - DESCRIPTION AND OPERATION
______________________________________________________________________
General
_______
A. The hydraulic fluid quantity indicating system will give a visual display of the quantity of fluid in each hydraulic system's hydraulic reservoir. The indication will be given as a percentage of the total reservoir system capacity. It will also give a visual warning if the fluid quantity becomes too low.
B. The system has a hydraulic fluid quantity transmitter for each hydraulic system reservoir and a hydraulic quantity interface module (HYQUIM). It uses the hydraulic control panel to give a warning when the fluid quantity decreases to 34% of the system reservoir capacity. It uses the EICAS HYD page to show the quantity of fluid in each system resevoir.
Hydraulic Fluid Quantity Transmitter (Fig. 1)
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A. The hydraulic fluid quantity transmitters are installed on the bottom of the hydraulic reservoirs. The operation of the four transmitters is the same. The dimensions of the outboard transmitters are different from the dimensions of the inboard transmitters.
B. The transmitters will measure the quantity of fluid in the hydraulic reservoirs. The transmitters send an analog signal that changes in proportion to the fluid quantity in the system. Electrical power for the transmitters is supplied by the 28 volt dc bus No. 3 or the ground handling bus.
Operation (Fig. 2)
_________
A. Functional Description
(1) The hydraulic fluid quantity transmitters send electrical signals to the HYQUIM. The HYQUIM sends the signals to the EICAS interface unit (EIU) and the hydraulic control module. The EIU then sends the signals to the EICAS HYD page on the auxiliary EICAS display. The EICAS HYD page will show system quantity in digital readouts as a percentage of the proper fluid level. A value of 1.00 is an indication that the reservoir is filled to the recommended full level. Acceptable levels for airplane departure are in the range of
0.80 to 1.10.
(2) When the fluid quantity is 0.34 or less, a LO (low quantity) message will show. This message shows adjacent to the digital indication of the hydraulic quantity on the auxiliary EICAS display. This low quantity message shows on the EICAS status, synoptic, and maintenance displays. This low quantity message shows when the airplane is on the ground, or in flight.
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