(a)
Supply electrical power (AMM 24-22-00/201).
(b)
Make sure the parking brake is off.
(c)
Set the Control Display Unit (CDU) to show page 2 of the Central Maintenance Computer (CMC) menu.
(d)
Push the Line Select Key (LSK) adjacent to "<OTHER FUNCTIONS" to show the other functions menu.
(e)
Push the LSK adjacent to "<INPUT MONITORING" to get access to the input monitoring pages.
(f)
Enter the ARINC word E/057/271/00 with the CDU keyboard.
(g)
Push LSK 1L for input of the word into the computer.
(h)
Make sure that bit 12 is 1 when the parking brake is off.
NOTE: The ARINC word shown on the CDU must look like this:
____
XXXXXXXXXXXXXXXX XXXX1XXXXXXXXXXX
The X digits are not related to this test. They can be 0 or 1.
(i)
Set the parking brake.
(j)
Make sure that bit 12 is 0 when the parking brake is set.
NOTE: The ARINC word shown on the CDU must look like this:
____
XXXXXXXXXXXXXXXX XXXX0XXXXXXXXXXX
The X digits are not related to this test. They can be 0 or 1.
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747-400 MAINTENANCE MANUAL
(k) Set the CDU to show the CMC menu.
S 795-021
(12)
Do a leak check of the parking brake:
(a)
Make sure that the system No. 4 wing and/or the tail FLT CONTROL SHUTOFF switches on the P461 panel is in the ON position.
(b)
Set the parking brake.
(c)
After 10 minutes, remove pressure from hydraulic system No. 4.
NOTE: Hydraulic systems No. 1 and 2 must not be pressurized.
____ Keep the brakes pressurized with the brake accumulator only.
(d) Do a minimum of one of these parking brake pressure tests:
NOTE: In all cases the pressure drop after 10 minutes must
____ be written down and must be less than 275 psi.
NOTE: Normally, passing one of these tests will supply
____ parking for at least 8 hours. The longer test times give a higher level of confidence should the leakage characteristic not be normal.
1) After 10 minutes, the parking brake pressure must not decrease more than 275 psi. 2) After 30 minutes, the parking brake pressure must not decrease more than 600 psi. 3) After 1 hour, the parking brake pressure must not decrease more than 800 psi. 4) After 2 hours, the parking brake pressure must not decrease more than 1000 psi.
(e)
If the parking brake pressure decreases faster than permitted, do the applicable Fault Isolation Procedure (FIM 32-44-00/101).
(f)
If the parking brake pressure drop is greater than allowed, fault isolation may be delayed and the airplane dispatched if this parking brake test is passed. 1) Pressurize hydraulic system 4 (AMM 29-11-00/201). 2) Set the parking brake. 3) Immediately remove the pressure from hydraulic system
No. 4. 4) After 10 minutes, parking brake pressure is not less than 825 psi.
(g)
Release the parking brake.
G.
Put the Airplane Back to Its Usual Condition
S 865-024
(1) Remove the power from hydraulic systems 1, 2 and 4
(AMM 29-11-00/201).
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S 865-025
(2) Make sure that the parking brake is released.
S 085-026
(3) Remove the pressure gage.
S 435-027
(4) Install a brake bleeder assembly at the brake.
NOTE:____ The brake bleeder assembly has a bleeder valve installed in a
bleeder adapter fitting. The bleeder adapter fitting is
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