L HYD SOV FAIL
(Caution)

• DAU 1 is sensing the hydraulic Shut-off Valve (SOV) open, and the DAU 3 is reporting the left fire handle out and/or the LH hydraulic SOV switch selected to "CLOSE".

OR

• DAU 1 is sensing the left hydraulic SOV closed, and the DAU 3 is reporting the left fire handle pushed in and/or the cockpit LH hydraulic SOV switch selected to "OPEN".

• Left Hydraulic Shut-off Valve (SOV) (L45)
• Data Acquisition Unit (DAU) 1 (A17)
• Data Acquisition Unit (DAU) 3 (A30)
• L Engine Firewall Shut-off Valve (EDP 1A) (L45)
• L Engine Fire Handle (A209)
• L Hydraulic SOC switch (SDS1)
• Junction Box 3 (JB3) Printed-Circuit Board 3 (PCB3) Relay K19
• Direct Current Power Center (DCPC) (A63)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Notice To Operators (NTO): None

Flight Operation Notifications Manual (FONM): None

• When replacing the pressure filters, a hydraulic lock has been known to prevent new filter installation. A "B" nut next to the filter manifold may need to be loosened or removed to bleed off pressure and allow the installation of the filter.
• Using the CMM for the Hydraulic SOV, it is possible to change the actuator of the valve without removing the hydraulic Valve. There may be internal seals in the valve portion that are preventing the valve to move freely, and has caused the actuator to fail.
• If you cannot move it by hand or feel binding, then replace the whole valve assembly.
• Do not move the valve indicator.
• You can use the test points on the JB boxes to verify the relay, or card integrity.
• Use the ground or power side of the relay coil to ensure the relay is functional. The relay is on the PCB card. The relay can be changed per the JB CMM.

1. Ensure fire handle is in, and power is off the affected system, or aircraft.
2. In the aft equipment bay, remove connector L45P1 at the LH Hyd. SOV and inspect the pins and sockets for damage or corrosion. Leave connector off.
3. CAUTION: Do not use the visual indicator to manually operate the valve. Damage to the indicator or valve may occur.
4. Install connector L45P1 on to LH Hyd. SOV.
5. Have an assistant do an operational test of the left hydraulic SOV, while you monitor the valve in the back. If no movement is seen on the valve when commanded, and the valve moves when you assist the indicator arm; ensure the EICAS Hyd. Page indications are accurate to the valve position and commands. Remember that CAIMS/ System Diagnostic/ ATA 31/ DAU 1A, and 1B/ LRU Test/ Discreet Inputs allows you to see DAU input from the LH Hyd. SOV.
6. If system checks are good, do close out. If fault remains continue with next step.
7. If the circuit breaker does not trip, go to step 10.
8. If the circuit breaker trips:

   1. Disconnect the left hydraulic SOV connector L45P1.
   2. Reset the left hydraulic SOV circuit breaker.
   3. If the circuit breaker does not trip, replace the left hydraulic SOV.
   4. If the circuit breaker trip, disconnect JB3 connector JB3EP1.
   5. If the circuit breaker does not trip, do a wiring check from left hydraulic SOV to JB3 and replace the JB3 Printed Circuit Board (PCB) 3 if required.
   6. If the circuit breaker trip, do a wiring check from JB3 to DCPC.

9. If the left hydraulic SOV moves to the close position, go to step 12.
10. If the left hydraulic SOV does not move to the close position:

    1. Disconnect the left hydraulic SOV connector L45P1, verify good ground at pin H.
    2. Do a voltage check between L45P1-G (+) to L45P1-H (-).
    3. If 28 volt is present, replace the left hydraulic SOV.
    4. If the voltage is not present, remove the JB3 face plate and check for 28 volts at PCB 3 TP-92.
    5. If the voltage is not good, go to step 10. G.).
    6. If the voltage is good, do a wiring check between JB 3 and the left hydraulic SOV connector L45P1 and repair applicable wiring.
    7. Remove the JB3 face plate and check for 28 volts at PCB 3 TP-94.
    8. If the voltage is not good, do a wiring check of wiring between JB3 and DCPC, if wiring is good, replace DCPC.
    9. If the voltage is good, disconnect JB3 connector JB3EP1 and check for:

       • Ground at JB3EP1-15 with the LH hydraulic SOV control switch IN.
       • Open at JB3EP1-15 with the LH hydraulic SOV control switch OUT.
       • Ground at JB3EP1-16 with engine No. 1 fire handle pulled.
       • Open at JB3EP1-16 with engine No. 1 fire handle pushed in.

    If any of the above readings are not good do a wiring check between the JB3 and the applicable panel and replace the applicable panel if required.
    10. Verify for continuity between JB3 connector JB3EP1-2 and JB3EP1-17.
    If there is no continuity, repair wire.
    11. If all of the above are good, replace the JB3. (Remember if you want to change the PCB 3 Card, that your fault could be in the back of the JB3 motherboard, and the card will not fix the problem).

11. If the left hydraulic SOV moves to the open position, go to step 14.
12. If the left hydraulic SOV does not move to the open position:

    1. Disconnect the left hydraulic SOV connector L45P1, verify good ground at pin H.
    2. Do a voltage check between L45P1-A (+) to L46P1-H (-).
    3. If 28 volts is present, replace the left hydraulic SOV.
    4. If the voltage is not present, remove the JB3 face plate and check for 28 volts at PCB 3 TP-96.
    5. If the voltage is not good, go to step 12. G.).
    6. If the voltage is good, do a wiring check between JB 3 and the left hydraulic SOV connector L45P1 and repair applicable wiring.
    7. Remove the JB3 face plate and check for 28 volts at PCB 3 TP-94.
    8. If the voltage is not good, do a wiring check of wiring between JB3 and DCPC, if wiring is good, replace DCPC.
    9. If the voltage is good, disconnect JB3 connector JB3EP1 and check for:

       • Ground at JB3EP1-15 with the LH hydraulic SOV control switch IN.
       • Open at JB3EP1-15 with the LH hydraulic SOV control switch OUT.
       • Ground at JB3EP1-16 with engine No. 1 fire handle pulled.
       • Open at JB3EP1-16 with engine No. 1 fire handle pushed in.

    If any of the above readings are not good, do a wiring check between the JB3 and the applicable panel and replace the applicable panel if required.
    10. Verify for continuity between JB3 connector JB3EP1-2 and JB3EP1-17. If there is no continuity, repair wire.
    11. If all of the above are good, replace the JB3. (Remember if you want to change the PCB 2 Card, that your fault could be in the back of the JB4 motherboard, and the card will not fix the problem).

13. Set the left engine fire handle IN and the LH hydraulic SOV switch OUT (open).
14. Disconnect the left hydraulic SOV connector L45P1 and install a jumper between L45P1- C and H.
15. If the L HYD SOV FAIL message goes away, replace the SOV.
16. If the L HYD SOV FAIL message is still shown, remove jumper and connect L45P1.
17. Interchange DAU 1 with another DAU.
18. Remove DAU 1 and check for the following readings:

    1. Ground at DAU 1 connector A17AP1-C6.
    2. Open at DAU 1 connector A17AP1-C13.

If any of the above readings are not good, do a wiring check between the left hydraulic SOV and the DAU 1.
19. If the above readings are good, select the left hydraulic SOV switch IN (close).
20. Check for the following readings:

    1. Open at DAU 1 connector A17AP1-C6.
    2. Ground at DAU 1 connector A17AP1-C13.

    If any of the above readings are not good, do a wiring check between the left hydraulic SOV and the DAU 1.

21. If the above readings are good, install the DAU 1.
22. Disconnect the left hydraulic SOV connector L45P1 and install a jumper between L45P1- E and H.
23. If the L HYD SOV FAIL message is still shown, replace the DAU 1.
24. Remove jumper and connect L45P1.
25. Do close out.