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(WARNING)
RED MESSAGE (CAUTION)
AMBER MESSAGE (ADVISORY)
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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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04/14/21

Message Overview:

Message Name:

AIRCRAFT BLEED SYSTEM

Message Code:

B3-302118

Associated CAS:

L ENG THRUST FAULT
(Advisory)

Reporting LRU: AC BLEED SYS
System Description: 76-11-00
Schematic Diagram: 27-32-00
30-12-00
36-11-00
76-11-00
77-10-00
Wiring Diagram: 27-32-00
30-11-00
30-12-00
36-11-00
36-15-00
71-50-00

Message Description:

Aircraft bleed system fault to left engine.

[MCID 1506]
Aircraft bleed system.
A fault related to the aircraft bleed management system was sensed.

The FADEC sees a discrepancy between the bleed command and the bleed status.
Whenever the engine control system detects an alteration to the provided thrust as compared to the expected one provided this alteration does not cause a loss of thrust control.

Possible Causes:

  • Aircraft Bleed Management System fault

    • Engine Bleed PBAs (Push Button Annunciator) (Anti-Ice and Air Cond)
    • Stall Protection Computer (SPC) (A178)
    • Integrated Air System Controller 1 (IASC) (A55 FWD)
    • Integrated Air System Controller 2 (IASC) (A56 AFT)
    • Data Concentrator Unit (DCU) (A14)
    • Input/Output Concentrator (IOC) (A4-IOC)
    • High Pressure Valve (HPV)

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

Forum Articles/Infoservice/Newsletter: None

  • If both L & R ENG THRUST FAULT are posted at the same time, first suspect the Wing Anti-Ice (WAI) PBA or the Stall Protection Computer (SPC), which are common to both engines.
  • If only one engine is posting ENG THRUST FAULT, then WAI PBA, SPC and DCU will most likely NOT be the root cause.
  • If ENG THRUST FAULT comes along with faults related to airspeed, altitude, stab, trim or spoiler, or following a change of Air Data Source selection on the Reversion Select Panel, the ADC is most likely the root cause.
  • If when cycling a Bleed PBA, the CAS message comes and goes, the fault is likely a discrepancy between the actual bleed status and the bleed command, possibly due to an ARINC failure.
  • A bleed fault due to a bleed valve or an A/I valve failure will most likely raise other MDC faults or CAS messages than only the ENG THRUST FAULT.
  • Experience has shown that not turning the WAI OFF after a "WING ANTI-ICE LEAK" CAS message could lead to an "ENG THRUST FAULT" CAS message. Refer to the AW listed above for more details.
  • When Batteries are "ON" and engines are not running, if WAI is "ON" while the rotary switch is on "NORM", the L & R ENG THRUST FAULT CAS message will display.
  • Check for the following MDC messages displayed with the fault:

    • - X-channel bus 1A (MCID 0905),
    • - X-channel bus 1B (MCID 0906),
    • - X-channel discrete 1A (MCID 0933),
    • - X-channel discrete 1B (MCID 0934).

    If any of the above MCID codes are posted, correct the cross channel faults first.

Quick Links:

Removal of the Integrated Air System (IAS) Controller AMM 21-31-01-000-801
Installation of the Integrated Air System (IAS) Controller AMM 21-31-01-400-801
Operational Test of the Integrated Air System (IAS) Controller AMM 21-31-01-710-801
Removal of the Stall Protection Computer AMM 27-32-01-000-801
Installation of the Stall Protection Computer AMM 27-32-01-400-801
Removal of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-000-801
Installation of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-400-801
Operational Test of the Input/Output Concentrator Unit (IOC) AMM 31-45-05-710-801
Switch/Lights and Bulbs - Removal/Installation SPM 20-11-05-04
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02

Troubleshooting Recommendations:

  1. Are any of the following CAS messages also displayed?

    1. If YES, start troubleshooting with those CAS message, as L/R ENG THRUST FAULT is likely a consequence of the other CAS message root cause.
    2. If NO, continue with next step.

  2. Check CAS messages displayed on the cockpit and go into the MDC to check if any of the following fault codes or any other B3 code related to the A/I system or Air Conditioning is present:

    1. Interrogate the MDC as follows:

      1. On the cursor control panel, ensure the toggle switch is to the right and select Anti-Ice, ECS and Fuel buttons simultaneously. Press ENTER. The MDC main menu should now be displayed on Display Unit #3.
      2. Using the joystick, select Current Faults (if the fault is active) or Aircraft History to research stored faults. From Aircraft History you can then select 'Fault History' and locate the fault. Going into advanced diagnostics will provide an Equation ID for the fault identified. 

      1. Select the MDC fault or equation from the drop down below to provide additional information to assist in troubleshooting.

    1. If yes, start troubleshooting with that other MDC code.
    2. If not, continue with the next step.

  3. Is the R ENG THRUST FAULT CAS message displayed at the same time as L ENG THRUST FAULT?

    1. If YES, continue with next step.
    2. If NO, go to step 8.

  4. Set Wing Source Rotary switch on NORM and cycle WAI PBA.

    1. If the CAS message comes and goes when cycling the WAI PBA, continue with next step.
    2. If cycling the WAI PBA has no effect on the CAS message, go to step 8.

  5. Go into the MDC to check if SPC output ARINC label 271 bits 17 and 18 to FADEC ("WAI selected OFF A" & "WAI selected OFF B" (1=OFF, 0=ON)), follow the WAI PBA position.

    1. Interrogate the MDC as follows:

      1. On the cursor control panel, ensure the toggle switch is to the right and select Anti-Ice, ECS and Fuel buttons simultaneously. Press ENTER. The MDC main menu should now be displayed on Display Unit #3.
      2. Using the joystick, select LRU INDEX/OPERATIONS, then STALL COMPUTER (27-35) and look at Label 271 bits value.

  6. Set Wing Source Rotary switch on NORM and cycle WAI PBA.

    1. If the Label 271 bits 17 & 18 follow the WAI PBA position, go to step 8.
    2. If the Label 271 bits 17 & 18 do not follow the WAI PBA position, continue with next step.

  7. Check wiring at SPC inputs A178AP1 and A178BP1 as follows:

    • At SPC A178AP1 pin 20, make sure ground is available while Wing Anti-Ice is deselected (OFF).
    • At SPC A178AP1 pin 20, make sure ground is NOT available while Wing Anti-Ice is selected (ON).
    • At SPC A178BP1 pin 20, make sure ground is available while Wing Anti-Ice is deselected (OFF).
    • At SPC A178BP1 pin 20, make sure ground is NOT available while Wing Anti-Ice is selected (ON).

    1. If wiring check failed, replace WAI selector switch. Do close out.
    2. If wiring check is good, replace SPC per AMM. Do close out.

  8. Cycle L BLEED PBA.

    1. If the CAS message disappears or reappears depending on the PBA position, continue with next step.
    2. If the CAS message remains even while cycling the PBA, go to step 13.

  9. Go into the MDC to check if L BLEED status given by IASC 1 follows PBA position while cycling the PBA.

    1. Interrogate the MDC as follows:

      1. On the cursor control panel, ensure the toggle switch is to the right and select Anti-Ice, ECS and Fuel buttons simultaneously. Press ENTER. The MDC main menu should now be displayed on Display Unit #3.
      2. Using the joystick, select LRU INDEX/OPERATIONS then STALL COMPUTER (27-35) and look at Label 271 bits value.

  10. Cycle the L BLEED STATUS PBA and check if L BLEED status (LEFT BLEED OFF: YES or NO) follows the PBA position. Note result and continue with next step.
  11. Go back to MDC main menu and check if L BLEED status delivered by IASC 2 follows PBA position while cycling the PBA.

    1. Interrogate the MDC as follows:

      1. Return to the MDC main menu displayed on Display Unit #3.
      2. Using the joystick, select LRU TESTING then IASC 2A. Choose TEST and press ENTER. Select AIR COND PANEL DISCRETE STATUS. Then select AIR COND/ENGINE PANEL STATUS.

  12. Cycle the L BLEED STATUS PBA and check if L BLEED status (LEFT BLEED OFF: YES or NO) follows the PBA position.

    1. If L BLEED status does not follow the PBA position at steps 10 and 12, replace L BLEED PBA. Do close out.
    2. If L BLEED status follows the PBA position only at step 10 and not at step 12, replace the IASC 2.
    3. If L BLEED status follows the PBA position only at step 12 and not at step 10, replace the IASC 1.
    4. If L BLEED status follows the PBA position at steps 10 and 12, continue with next step.

  13. Refer to the Honeywell LMM (Subtask 72-00-00-810-323-A01).

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