Message Name:

L HYD SOV FAIL

Message Code:

00LHSVFL

Associated CAS:

L HYD SOV FAIL
(Caution)

Under either conditions below:

• Data Acquisition Unit (DAU) 1 is sensing the Hydraulic Shut-Off Valve (SOV) open, and the Data Acquisition Unit (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)
• Data Acquisition Unit (DAU) 1 (A17)
• Data Acquisition Unit (DAU) 3 (A30)
• Fire-Handle-Switch
• Left Hydraulic Shut-Off Valve (SOV) Cockpit Switch (E13)
• Junction Box (JB3)
• DC Power Center (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 Hyd. 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. With no Hydraulic pressure in the system you should be able to move the valve by hand using the indication lever. If you can not move it by hand or feel binding, then replace the whole valve assembly. Do not use tools to 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. In the aft equipment bay, physical move the right hydraulic SOV to the open or closed position, (opposite to what it is failed at). Ensure hydraulic pressure is at 0, and do this by hand only. Use a rag to prevent hand indentations. Move valve a few times to verify no binding, or damage.
4. Physically move the valve to the open position.
5. Install connector L45P1 on to LH Hyd. SOV.
6. Have an assistant do an operational test of the right 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.

   1. If system checks are good, do close out.
   2. If fault remains, continue with next step.

7. Check if the circuit breaker trips.

   1. If the circuit breaker does not trip, go to step 12.
   2. If the circuit breaker trips, continue with next step.

8. Disconnect the left hydraulic SOV connector L45P1. Reset the left hydraulic SOV circuit breaker.

   1. If the circuit breaker does not trip, go step 39.
   2. If the circuit breaker trip, continue with next step

9. Disconnect JB3 connector JB3EP1 and check if the circuit breaker trips.

   1. If the circuit breaker trip, go to step 11.
   2. If the circuit breaker does not trip, continue with next step.

10. Perform a wiring check from left hydraulic SOV to JB3.

    1. If wiring checks are not good, repair defective wiring as required and replace the JB3 Printed Circuit Board (PCB) 3 if required and do close out.
    2. If wiring checks are good, continue with next step.

11. Perform a wiring check from JB3 to DCPC.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

12. Check the position of the left hydraulic SOV.

    1. If the left hydraulic SOV moves to the close position, go to step 21.
    2. If the left hydraulic SOV does not move to the close position, continue with next step.

13. Disconnect the left hydraulic SOV connector L45P1, verify good ground at L45P1-H and perform a voltage check between L45P1-G (+) to L45P1-H (-).

    1. If 28 VDC is present, go step 39.
    2. If 28 VDC is not present, continue with next step.

14. Remove the JB3 face plate and check for 28 volts at PCB 3 TP-92.

    1. If the voltage is not good, go to step 16.
    2. If the voltage is good, continue with next step.

15. Perform a wiring check between JB 3 and the left hydraulic SOV connector L45P1.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

16. Remove the JB3 face plate and check for 28 volts at PCB 3 TP-94.

    1. If the voltage is good, go to step 18.
    2. If the voltage is not good, continue with next step.

17. Perform a wiring check of wiring between JB3 and DCPC.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, replace DCPC and continue with next step.

18. Disconnect JB3 connector JB3EP1 and check for the following readings:

    Condition	JB3	Expected Result	Result
    SDS1-IN	JB3EP1-15	Ground
    SDS1-OUT	JB3EP1-15	Open
    A209-Pull	JB3EP1-16	Ground
    A209-Push	JB3EP1-16	Open

    1. If all of the above readings are good, replace the JB3 and do close out.
       NOTE: 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.
    2. If any of the above readings are not good, continue with next step.

19. Perform a wiring check between the JB3 and the applicable panel.

    1. If wiring checks are not good, repair defective wiring as required and replace the applicable panel if required and do close out.
    2. If wiring checks are good, continue with next step.

20. Perform a continuity check between JB3 connector JB3EP1-2 and JB3EP1-17.

    1. If there is no continuity, repair wiring as required and do close out.
    2. If there is continuity, continue with next step.

21. Check the position of the left hydraulic SOV.

    1. If the left hydraulic SOV moves to the close position, go to step 30.
    2. If the left hydraulic SOV does not move to the close position, continue with next step.

22. Disconnect the left hydraulic SOV connector L45P1, verify good ground at L45P1-H and perform a voltage check between L45P1-A (+) to L45P1-H (-).

    1. If 28 VDC is present, go step 39.
    2. If 28 VDC is not present, continue with next step.

23. Remove the JB3 face plate and check for 28 volts at PCB 3 TP-96.

    1. If the voltage is not good, go to step 25.
    2. If the voltage is good, continue with next step.

24. Perform a wiring check between JB 3 and the left hydraulic SOV connector L45P1.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

25. Remove the JB3 face plate and check for 28 volts at PCB 3 TP-94.

    1. If the voltage is good, go to step 27.
    2. If the voltage is not good, continue with next step.

26. Perform a wiring check of wiring between JB3 and DCPC.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, replace DCPC and continue with next step.

27. Disconnect JB3 connector JB3EP1 and check for the following readings:

    Condition	JB3	Expected Result	Result
    SDS1-IN	JB3EP1-15	Ground
    SDS1-OUT	JB3EP1-15	Open
    A209-Pull	JB3EP1-16	Ground
    A209-Push	JB3EP1-16	Open

    1. If all of the above readings are good, replace the JB3 and do close out.
       NOTE: 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.
    2. If any of the above readings are not good, continue with next step.

28. Perform a wiring check between the JB3 and the applicable panel.

    1. If wiring checks are not good, repair defective wiring as required and replace the applicable panel if required and do close out.
    2. If wiring checks are good, continue with next step.

29. Perform a continuity check between JB3 connector JB3EP1-2 and JB3EP1-17.

    1. If there is no continuity, repair wiring as required and do close out.
    2. If there is continuity, continue with next step.

30. Set the left engine fire handle IN and the LH hydraulic SOV switch OUT (open).
31. Disconnect the left hydraulic SOV connector L45P1 and install a jumper between L45P1- C and H.

    1. If the L HYD SOV FAIL message goes away, replace the SOV.
    2. If the L HYD SOV FAIL message is still shown, remove jumper and connect L45P1.

32. Interchange DAU 1 with another DAU 3.

    1. If system checks are good, go to step 38.
    2. If fault remains, continue with next step.

33. Remove DAU 1 and check for the following readings:

    DAU 1	Expected Result	Result
    A17AP1-C6	Ground
    A17AP1-C13	Open

    1. If the above readings are good, go to step 35.
    2. If any of the above readings are not good, continue with next step.

34. Perform a wiring check between the left hydraulic SOV and the DAU 1.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

35. Select the left hydraulic SOV switch IN (close) and check for the following readings:

    DAU 1	Expected Result	Result
    A17AP1-C6	Open
    A17AP1-C13	Ground

    1. If the above readings are good, go to step 38.
    2. If any of the above readings are not good, continue with next step.

36. Perform a wiring check between the left hydraulic SOV and the DAU 1.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

37. Disconnect the left hydraulic SOV connector L45P1 and install a jumper between L45P1- E and H.

    1. If the L HYD SOV FAIL message is not shown, remove jumper and connect L45P1.
    2. If the L HYD SOV FAIL message is still shown, continue with next step.

38. Replace DAU 1.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

39. Replace left hydraulic SOV.
40. Do close out.