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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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07/14/23

Message Overview:

Message Name:

NO FQGC-A BUS TO RDC

Message Code:

B3-006793

Associated CAS:

FUEL QUANTITY FAULT
(Advisory)

Reporting LRU: FQGC
System Description: 28-41-00
Schematic Diagram: 28-41-00
Wiring Diagram: 28-41-01

Message Description:

FQGC-A bus data invalid or missing to RDC.

Possible Causes:

  • Fuel Quantity Gauging Computer (FQGC) (A57)
  • Remote Data Concentrator (RDC) (A13)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/ Service Bulletin: 

  • AW300-28-0398 - SmartFix Plus Fuel System Troubleshooting Updates

Forum Articles/Infoservice/Newsletter: None

NOTE: Flight crew should be aware that if 'FUEL QTY FAULT' or 'FUEL QTY FAIL' CAS is posted, they should verify fuel synoptic page and report any abnormal conditions or parameters.

Quick Links:

Standard Aircraft Configuration for Maintenance AMM 12-00-00-867-803
Use of Fuel Biocide Additive When Pressure Refueling AMM 12-11-01-620-801
Pressure Refueling AMM 12-11-01-650-801
Use of Fuel Anti-Icing Additive When Pressure Refueling AMM 12-11-01-660-801
Suction Defueling AMM 12-11-09-650-801
Use of Fuel Biocide Additive When Gravity Refueling AMM 12-11-13-620-801
Gravity Refueling AMM 12-11-13-650-801
Use of Fuel Anti-Icing Additive When Gravity Refueling AMM 12-11-13-660-801
Microbial Growth Test AMM 12-11-28-280-801
Fuel-System Safety Precautions AMM 28-00-00-910-801
Cleaning of the Fuel Tank AMM 28-10-00-160-801
Biocide Treatment of the Fuel Tank AMM 28-10-00-620-801
Drain Water from the Fuel Tank AMM 28-10-00-680-801
Prepare Fuel Tank for Access AMM 28-10-00-840-801
Removal of Fuel Fumes AMM 28-10-00-840-802
Close the Fuel Tank after Maintenance AMM 28-10-00-840-803
General Visual Inspection of the Fuel Storage System AMM 28-10-00-210-801
Operational Check for Water in the Fuel AMM 28-10-00-750-801
Component Location AMM 28-11-00-992-801
Component Location AMM 28-41-00-992-801
Built-In Test of the Fuel-Quantity Gauging System AMM 28-41-00-740-801
Removal of the Fuel Quantity Computer AMM 28-41-01-000-801
Removal of the Fuel Quantity Probe AMM 28-41-13-000-801
Installation of the Fuel Quantity Probe AMM 28-41-13-400-801
Removal of the Fuel Quantity Probe with Compensator AMM 28-41-13-000-802
Installation of the Fuel Quantity Probe with Compensator AMM 28-41-13-400-802
Capacitance Check of the Fuel Quantity Probes AMM 28-41-13-760-801
Cleaning of the Fuel Quantity Probes AMM 28-41-13-160-801
Removal of the Remote Data Concentrator (RDC) AMM 31-41-05-000-802
Installation of the Remote Data Concentrator (RDC) AMM 31-41-05-400-802
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
Data Download from the Maintenance Diagnostic Computer (MDC) AMM 45-45-01-970-802
Safety Precautions - Maintenance Practices - ALL SPM 20-00-01-02-01
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL SPM 20-20-00-02-01

Troubleshooting Recommendations:

  1. Make sure Refuel/Defuel panel is set to OFF and reset the following circuit breakers, waiting 10 seconds before pushing the breakers back.:

    Circuit Breaker Name
    CB3-C3 FUEL QTY 1
    CB4-C3 FUEL QTY 2
    CB1-D2 EICAS RDC A
    CB2-D2 EICAS RDC B

    1. If the cyan 'FUEL QTY FAULT' EICAS message is still displayed, go to next step.
    2. If the cyan 'FUEL QTY FAULT' EICAS message is no longer displayed, do close out.

  2. Verify fuel synoptic page for any MAGENTA parameters other than fuel quantities.

    1. If any abnormal MAGENTA indications other than fuel quantities are displayed on the Fuel Synoptic page, or were reported displayed by pilots at a time that can be correlated to B3-006793, replace RDC.
    2. If there are no abnormal MAGENTA parameters, go to next step.

  3. Re-rack the Fuel Quantity Gauging Computer (FQGC). Is the fault message still present?

    1. If YES, go to next step.
    2. If NO, do close out.

  4. Carry out wiring checks per Table 1. Repair or replace any defective wiring as required.

    Table 1
    RDC (A13) FQGC (A57)
    Connector Pin + Connector Pin - Expected Result
    A13DP1 A1 A57BP1 67 Continuity
    A13DP1 B1 A57BP1 68 Continuity

  5. Do power checks per Table 2. Repair or replace any defective wiring as required.

    Table 2
    CONNECTOR PINS (28 VDC) PIN (ground) Expected Results
    A57BP1 95 97 ≈28 VDC

  6. If wiring is found serviceable, replace FQGC.
  7. If fault continues, replace RDC.
  8. Do close out.

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