-There is no pressure increase when you close the shutoff valves for the wing and tail.
If this procedure does not clearly identify the defective component, or the pressure readings do not agree, you must do the Hydraulic System Internal Leakage Check procedure.
TASK 29-11-00-706-682
15. Movement of the Fluid Between the Hydraulic Systems Check_________________________________________________________
A. References
(1)
09-11-00/201, Towing
(2)
24-22-00/201, Manual Control
(3)
29-11-00/201, Main Hydraulic Supply System
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A
747-400
MAINTENANCE MANUAL
B. Access
(1)
Location Zone
221/222 Control Cabin
C.
Prepare for Check
S 496-683
(1)
Make sure the ground lockpins for the landing gear are installed (AMM 09-11-00/201).
S 866-684
(2)
Supply electrical power (AMM 24-22-00/201).
S 866-685
(3)
Make sure the ALTN FLAPS ARM switch is OFF.
S 866-686
(4)
Put the A/P ENGAGE switches (L, C, and R) on the control panel for the AFCS mode in the OFF position.
S 866-687
(5)
Make sure the selector handle for the landing gear, on the first officer's panel, P2, is in the OFF position.
S 866-688
(6)
Put the STAB TRIM 2 and STAB TRIM 3 switches, on the control stand, in the NORM position.
S 866-689
(7)
Put the LOWER and UPPER YAW DAMPER switches, on the overhead panel, P5, to the INOP position.
D.
Do a check for the movement of the fluid from one hydraulic system to the three other hydraulic systems.
NOTE: Do this procedure for each hydraulic system, one system at a time.
____ S 866-690
(1) Pressurize the hydraulic system, on which you will do the check, with a demand pump (AMM 29-11-00/201).
NOTE: The three other hydraulic systems must not be pressurized.
____
S 866-691
(2)
Operate the flight controls through four or five cycles to cause the hydraulic fluid to become warm.
(3)
Put all the flight controls in the neutral position.
S 866-692
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A
747-400 MAINTENANCE MANUAL
S 796-693
(4)
Do a check of the components of the lateral flight controls.
(a)
Find the switches for the FLT CONTROL HYD POWER on the pilot's overhead maintenance panel, P461. 1) Put the WING switches, for the hydraulic systems No. 1, 2,
3, and 4, to the NORM position. a) Make sure the VALVE CLOSED lights for the four switches are off.
2) Put the TAIL switches, for the hydraulic systems No. 1, 2, 3, and 4, to the SHUTOFF position. a) Make sure the VALVE CLOSED lights for the four switches
come on.
(b)
Monitor the hydraulic quantity indication, on the EICAS status display, for the conditions which follow: 1) The quantity of the hydraulic fluid increases in one or
more of the three systems which are not pressurized. 2) The quantity of the hydraulic fluid decreases in the system which is pressurized.
(c)
Refer to the chart which follows, for the possible sources of the movement of the fluid between the hydraulic systems. 1) These are the applicable conditions for the chart which
follows: a) The supply shutoff valves for the aileron and spoilers must be in the open position. b) The supply shutoff valves for the rudder and elevator must be in the closed position. c) The systems which are identified with the flagnote *[1] must not be pressurized. d) The systems which are identified with the flagnote *[2] must be pressurized.
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