(h)
Increase supply pressure from the test box to 15 psig.
(i)
Make sure the PRV is fully open by 15 psig. 1) Make sure the PRV is open by visually inspecting the position switch. 2) Make sure the PRV shows an OPEN indication on the ECS maintenance page.
3) If the PRV fully opens but does not indicate OPEN on the ECS maintenance page, troubleshoot the position switch and/or wiring.
4) Make sure the reference pressure is equal to or greater than 12 psig.
5) If the reference pressure is less than 12 psig do these steps: a) Check the fittings and tubing between the PRV and PRV
controller for leakage with a soap solution and repair as necessary. b) If no leaks are found, do these steps:
1.
Increase the supply pressure to 20 psig.
_
2.
If the reference pressure is less than 12 psig,
_ replace the PRV controller (AMM 36-11-20/401).
(j) If the PRV did not fully open, do these steps:
1) Check the fittings and tubing between the PRV controller and the PRV for leaks with a soap solution and repair as necessary.
2) If no leaks are found, do these steps: a) Increase the supply pressure up to 20 psig maximum or until the reference pressure reaches 12 psig. b) If the reference pressure is 12 psig and the PRV is not open, replace the PRV (AMM 36-11-19/401).
c) If the reference pressure is less than 12 psig and the PRV is not open, replace the PRV controller (AMM 36-11-20/401).
(k)
Reduce the reference pressure to zero.
(l)
Reduce the supply pressure to zero.
S 715-057
(4)
Test the PRV controller operation (Fig. 503 SH 2)
(a)
Disconnect the reference pressure (blue) hose from the actuator fitting or tee fitting.
(b)
Remove the actuator fitting and install the locking pin or remove the tee fitting and install the signal pressure sense line.
(c)
Disconnect the tubing from the actuator pressure port fitting (90-degree elbow) on the PRV controller.
(d)
Connect the straight fitting to the actuator pressure port fitting (90-degree elbow) on the PRV controller.
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747-400 MAINTENANCE MANUAL
(e)
Connect the reference pressure (blue) hose to the straight fitting in the actuator pressure port.
(f)
Use the 'HIGH PRESSURE GAUGE' on the test box.
(g)
Increase the supply pressure to 100 psig.
(h)
Increase the regulated pressure to the values listed in the table below.
NOTE: You may have to adjust the supply pressure to maintain
____
100 psig.
(i) Make sure the reference pressure is within the limits listed in the the table below.
NOTE: Let the reference pressure become stable before you take
____
a reading.
Supply Regulated Reference Pressure Pressure Pressure (psig) (psig) (psig)
100 55 53-79
100 60 38-59
100 65 27-43
100 70 20-29
100 75 16-21
(j) If the reference pressure is not within these limits, then replace the PRV Controller (AMM 36-11-20/401).
S 715-059
(5)
Test the PRV controller shutoff solenoid
(a)
Decrease the supply pressure to 50 psig.
(b)
Decrease the regulated pressure to zero.
(c)
Make sure the PRV is open.
(d)
Select the bleed switch on the overhead panel to OFF.
(e)
Make sure the reference pressure is less than or equal to 2 psig. 1) If the reference pressure is not less than or equal to 2
psig, remove the connector on the PRV controller. 2) Measure the voltage across pins 1 and 2 while the bleed switch is changed to the OFF position.
NOTE: The 28 VDC "pulse" can only be measured while the
____ switch is changed from ON to OFF. You should use an analog meter to see the pulse.
3) If the voltage is 28 VDC, replace the PRV Controller (AMM 36-11-20/401) 4) If the voltage is not 28 VDC, troubleshoot the wiring between the connector and the ASCTU.
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