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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
CYAN MESSAGE (STATUS)
WHITE MESSAGE Require immediate crew attention. These messages are accompanied by flashing master warning, triple chime attenson with or without voice message or dedicated tone. Require immediate crew awareness and future crew action may be required in the form of alternate system selection or performance limitation. These message are accompanied by flashing master caution and a single chime. Indicate safe or normal system operation which require crew awareness, over and above the dark cockpit philosophy. Indicate minor failures or reduction in systems capability, which require no crew action.

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For AOG assistance contact:

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Quick Links

03/10/21

Message Overview:

Message Name:

OUTBOARD BRAKE FAIL

Message Code:

B3-006383

Associated CAS:

OUTBD BRAKES FAIL
(Caution)

L OUTBD BRAKE FAIL
(Caution)

R OUTBD BRAKE FAIL
(Caution)

Reporting LRU: BRAKE CTRL UNIT
System Description: 32-43-00
Schematic Diagram: 32-43-00
Wiring Diagram: 32-43-01

Message Description:

The Brake Control Unit has detected a fault with the outboard brake hydraulic control, or the outboard brake control unit.

Possible Causes:

  • Brake Control Unit (BCU) (A67)
  • Left Brake Control Valve (BCV) (MPE23)
  • Right Brake Control Valve (BCV) (MPE24)
  • Left Brake Shut-Off Valve (BSOV) (MPE27)
  • Right Brake Shut-Off Valve (BSOV) (MPE28)
  • Left Break Pressure Transducer (MT97)
  • Right Break Pressure Transducer (MT98)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

Quick Links:

Removal of the Brake Control Unit AMM 32-43-01-000-801
Installation of the Brake Control Unit AMM 32-43-01-400-801
Removal of the Brake Control Valve AMM 32-43-09-000-801
Installation of the Brake Control Valve AMM 32-43-09-400-801
Operational Test of the Brake Control Valve Resistance AMM 32-43-09-710-801
Removal of the Brake Pressure Transducer AMM 32-43-17-000-801
Installation of the Brake Pressure Transducer AMM 32-43-17-400-801
Removal of the Brake Shutoff Valve AMM 32-43-25-000-801
Installation of the Brake Shutoff Valve AMM 32-43-25-400-801
Removal of the Brake Hydraulic Fuse AMM 32-43-33-000-801
Installation of the Brake Hydraulic Fuse AMM 32-43-33-400-801
Removal of the Wheel Speed Transducer AMM 32-43-49-000-801
Installation of the Wheel Speed Transducer AMM 32-43-49-400-801
Data Download from the Maintenance Diagnostic Computer (MDC) AMM 45-45-01-970-802
Standard Practices - Replace Wiring SPM 20-12-00-02
Standard Practices - Electrical Wiring - Continuity Test - Adjustment/Test SPM 20-12-01-05
Standard Practices - Wire Repair SPM 20-12-10-02

Troubleshooting Recommendations:

SETUP:

  1. Pressurize the left and right hydraulic systems.
  2. Make sure the inboard and outboard brake accumulators are charged (inboard and outboard brakes 'PRESS NORM' indication is green on the hydraulic synoptic page).
  3. Depressurize the left and right hydraulic systems.

FAULT CONFIRMATION:

NOTE: Do not re-pressurize the hydraulic systems during this procedure. This is to ensure that the BCU does not perform the power-up hydraulic test sequence. If the inboard or outboard brake 'PRESS NORM' indication becomes amber during the procedure, reset circuit breaker RCBP-C15 (OUTBD BRAKES) after having recharged the accumulators.

  1. Reset circuit breaker RCBP-C15 (OUTBD BRAKES).

    1. After 30 seconds, if the '(L) (R) OUTBD BRAKE FAIL' CAS message IS NOT shown, go to step 3 of this section.
    2. After 30 seconds, if the '(L) (R) OUTBD BRAKE FAIL' CAS message IS shown, continue with next step.

  2. Access the MDC system parameters page.

    1. If the left or right inboard pressure indication is over 250 psi, replace pressure transducer.
    2. If the left or right inboard pressures is between 130 and 250 psi, read the note below and go to step 3 of this section.
      NOTE: While pressures between 130 psi and 250 psi are not the cause of the CAS message, it is abnormal to have pressure in this range with no brake pedal input. Consider investigating.

      • With BCU PN 142-045-1, the brake control valve may have a high internal leakage, or the pressure transducer may be faulty.
      • With BCU PN 142-045-2, the pressure transducer may be faulty.

    3. If pressures are below 130 psi, continue with next step.

  3. Access the MDC system parameters page.
  4. Gradually apply the left and right brake pedals while observing the left and right outboard brake pressure indications.

    1. If both the left and right outboard brake pressures do not increase, go to step 1 of the 'FAULT ISOLATION' section.
    2. If only one brake pressure increases, go to step 3 of the 'FAULT ISOLATION' section.
    3. If both brake pressure increase and the '(L) (R) OUTBD BRAKE FAIL' CAS message IS NOT displayed, go to step 8 of the 'FAULT ISOLATION' section.
    4. If both brake pressure increase and the '(L) (R) OUTBD BRAKE FAIL' CAS message IS displayed, go to step 13 of the 'FAULT ISOLATION' section.
      NOTE: Pressures may decrease when the fault message appears.

FAULT ISOLATION:

  1. Inspect inboard shutoff valve wiring and connector.

    1. If defects are found, repair defective wiring as required.
    2. If no defects are found, continue with next step.

  2. Swap the inboard and outboard Brake Shutoff Valves (BSOV) and carry out the 'FAULT CONFIRMATION' section.

    1. If the fault followed to the inboard side, replace faulty BSOV.
    2. If the fault did not follow, replace the BCU.

  3. Access the MDC LRU TEST page and carry out the outboard 'BCV RESISTANCE TEST'.

    1. If the test fails, inspect the outboard brake control valve connector and wiring and If no fault is found, replace the outboard BCV.
    2. If test passes, continue with next step.

  4. Have a second person action and hold the brake hydraulic fuse bypass lever of the brake that did not show a pressure increase.
  5. Apply pressure to the relevant brake pedal and observe the brake pressure indication.

    1. If pressure increases, continue with next step.
    2. If pressure does not increase, go to step 7.

  6. Carry out a leak check downstream of the brake hydraulic fuse and if no leak is found, replace the brake hydraulic fuse.
  7. Swap the inboard and outboard Brake Control Valves (BCV) and carry out the 'FAULT CONFIRMATION' section.

    1. If the fault followed to the inboard side, replace the faulty BCV.
    2. If the fault did not follow, replace the BCU.

  8. Pressurize the right hydraulic system.

    1. If the '(L) (R) OUTBD BRAKE FAIL' CAS message is displayed, replace the BCU.
    2. If not, continue with next step.

  9. Access the MDC LRU TEST page and carry out the outboard 'HARDWARE MONITOR TEST'.

    1. If the test fails, replace the BCU.
    2. If the test passes, continue with next step.

  10. Depressurize the right hydraulic system.
  11. Carry out the outboard BCU 'EPROM TEST'.

    1. If the test fails, replace the BCU.
    2. If the test passes, continue with next step.

  12. Perform a leak check of the outboard brake system.

    1. If no leak found, there is no fault in the system.
    2. If a leak is found, rectify as required.

  13. Access the MDC LRU TEST page and carry out the inboard 'BCV RESISTANCE TEST'.

    1. If the test fails, inspect the outboard BCV connector and wiring and If no fault is found, replace the outboard BCV.
    2. If the test passes, continue with next step.

  14. Perform a leak check of the outboard brake system.

    1. If leaks are found, rectify as required.
    2. If no leaks are found, continue with next step.

  15. Swap the inboard and outboard Brake control valves and carry out the 'FAULT CONFIRMATION' section.

    1. If the fault followed to the other side, replace the faulty BCV.
    2. If the fault did not follow to the other side, continue with next step.

  16. Reset circuit breaker RCBP-C15 (OUTBD BRAKES).
  17. Gradually apply the left brake pedal.

    1. If the '(L) (R) OUTBD BRAKE FAIL' CAS message is displayed, reset circuit breaker RCBP-C15 (OUTBD BRAKES) and continue with next step.
    2. If not, continue with next step.

  18. Gradually apply the right brake pedal.

    1. If both left and right brake pedal application caused the '(L) (R) OUTBD BRAKE FAIL' CAS message to be displayed, replace the BCU.
    2. If only 1 brake pedal application caused the '(L) (R) OUTBD BRAKE FAIL' CAS message to be displayed, continue with next step.

  19. Swap the outboard left and outboard right pressure transducers and test again.

    1. If the fault follows to the other side, replace the faulty pressure transducer.
    2. If the fault does not follow to the other side, replace the BCU.

NOTE: If further assistance is required, send a download of the BCU NVM to Bombardier CRC with a complete description of the issue and troubleshooting steps taken.

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