(10)
Turn the tee fittings until they align with the sense lines. S 434-026
(11)
Tighten the clamp nuts on both ends of the trim air PRSOV. S 434-027
(12)
Hold the tee fittings while you tighten the tube nuts. S 534-050
(13)
Remove the caps which you installed on the sense lines.
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747-400 MAINTENANCE MANUAL
S 164-073
CAUTION: MAKE SURE YOU DISCONNECT THE VALVE SENSE LINES TO AVOID DAMAGE
_______
TO THE VALVE DIAPHRAM FROM THE CLEANING PRESSURE.
(14) Make sure that the sense lines are clean, if not, do this steps:
(a) Use a vacuum cleaner or compressed air to remove unwanted materials in the sense lines.
S 434-028
(15)
Connect the sense lines to the tee fittings.
S 424-075
(16)
To connect the bonding jumper to the valve, do these steps:
(a) Use the solvent and the cheesecloth to clean and dry the bonding surfaces (AMM 20-11-14/701).
NOTE: The bonding surfaces must be clean and dry to
____ provide a good electrical ground path.
(b)
Install the screw, washers, and nut to connect the bonding jumper to the valve.
(c)
Use the bonding meter to measure the resistance between the bonding jumper terminal and the actuator near the bonding jumper connection. (AMM 20-22-01/601).
NOTE: If necessary, you can remove a small area of the
____ surface finish to make the measurement.
(d)
If the resistance is greater than 0.0025 ohms, then disassemble the bonding jumper connection, repeat the cleaning and assembly steps, and measure the resistance again.
(e)
Put a thin coating of the alodine on the exposed metal surfaces of the bonding jumper connection to protect against corrosion.
(f)
If you removed any of the surface finish from the valve, then use the alodine to repair the surface finish.
S 434-029
(17)
Connect the bonding jumper to the trim air PRSOV.
S 434-030
(18)
Connect the electrical connector, DV110, to the trim air PRSOV.
F. Do a Test of the Trim Air PRSOV
S 864-031
(1) Remove the DO-NOT-CLOSE tag and close this circuit breaker on the P6 main power distribution panel:
(a) 6F30, MASTER TRIM AIR CONT
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747-400 MAINTENANCE MANUAL
S 864-052
(2)
Supply electrical power (AMM 24-22-00/201).
S 864-053
(3)
Supply power to EICAS (AMM 31-61-00/201).
S 864-054
(4)
Operate the air conditioning pack(s) while you monitor the EICAS ECS maintenance page (AMM 21-00-00/201).
S 214-055
(5)
Make sure the TRIM AIR PRESS indication, on the EICAS ECS
maintenance page, is between 5.0 and 10.0.
S 864-056
(6)
Put the TRIM AIR switch to OFF at the P5 overhead panel.
S 214-057
(7)
Make sure the TRIM AIR PRESS indication, on the EICAS ECS
maintenance page, is between 0.0 and 0.5.
S 214-058
(8)
Do a check of the electrical and pneumatic connections if the trim air PRSOV does not operate correctly.
S 864-059
(9)
Put the TRIM AIR switch to ON.
S 214-060
WARNING:_______DO NOT TOUCH THE DUCTS. THE DUCTS ARE VERY HOT AND CAN BURN YOU VERY BADLY IF YOU TOUCH THEM.
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