FUEL QUANTITY FAULT
(Advisory)

The cyan 'FUEL QUANTITY FAULT' advisory Crew Alerting System (CAS) message indicates the left or right channel has detected a fault or loss of temperature compensation.

• Fuel System Computer Unit (A57)
• Remote Data Concentrator (RDC) (A13)

Advisory Wire/Service Bulletin:

• AW300-28-0118 - No Fault Found Initiative: Fuel Quantity and Gauging Computer (FQGC)
• AW300-28-0138 - Fuel Tank Sumping
• AW300-28-0398 - SmartFix Plus Fuel System Troubleshooting Updates

Full Throttle Blog/Forum Articles/Infoservice/Newsletter: None

Flight Operation Notifications Manual (FONM): None

NOTES:

• Because water has a higher dielectric constant than fuel, water in fuel tanks will affect the reading of fuel quantity probes if it comes in contact with them. The reading will become out of range and the FQGC will stop sending fuel quantity for that tank (magenta dashes). At a certain point, enough water in a fuel quantity probe will 'short' the probe's concentric tubes and collapse the oscillator signal feeding all probes for that tank. The FQGC will identify the oscillator as faulty and will shut down the affected tank channel and identify the fault as internal to the FQGC (MDC code B3-006789).
• Before replacing the FQGC, make sure the failure is not caused by the presence of water contamination on fuel probes.
• When sumping water from affected fuel tank it is preferable to have fuel probes immersed in fuel, in order for the water to pool at the bottom of the fuel tank.
• To get most of the water to the bottom of the tank, for T/S purposes do not move aircraft for at least 2 hours before sumping.
• You can view and compare the Left wing and Right wing Fuel probe capacitance values via the MDC on the Fuel Probe Capacitance Display page. If one probe seems off compared to the other side, the affected probe may need to be cleaned.
• Fill the Detailed FQGC Troubleshooting Report if Fuel Quantity Gauging Computer (FQGC) pn 738360-1-2 is replaced.

1. Pull and reset the Fuel Quantity system breakers (CB3-C3, CB4-C3), recheck the system for the fault.
   
2. 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. 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 Message History and locate the fault. Going into advanced diagnostics will provide an equation id for the fault identified.
   3. Select the MDC fault or equation from the drop down below to provide additional information to assist in troubleshooting.
      Select the MDC Codes:B3-006788 - NO FQGC OUTPUT TO RDC [FQGC]B3-006789 - INTERNAL FAULT [FQGC]B3-006790 - NO L-GP-5 BUS INPUT [FQGC]B3-006791 - NO R-GP-5 BUS INPUT [FQGC]B3-006792 - WOFFW INPUT DISAGREE [FQGC]B3-006793 - NO FQGC-A BUS TO RDC [FQGC]B3-006794 - NO FQGC-B BUS TO RDC [FQGC]B3-006795 - AHC INPUT DISAGREE [FQGC]B3-007021 - OPN/SHRT/OUT OF RANGE [L COLLECT PROBE]B3-007128 - OPN/SHRT/OUT OF RANGE [L TNK PR 8/COMP]B3-007135 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 1]B3-007136 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 2]B3-007137 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 3]B3-007138 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 4]B3-007139 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 5]B3-007140 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 6]B3-007141 - OPN/SHRT/OUT OF RANGE [L TNK PROBE 7]B3-007690 - OPN/SHRT/OUT OF RANGE [R COLLECT PROBE]B3-007850 - OPN/SHRT/OUT OF RANGE [R TNK PR 8/COMP]B3-007857 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 1]B3-007858 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 2]B3-007859 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 3]B3-007860 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 4]B3-007861 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 5]B3-007862 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 6]B3-007863 - OPN/SHRT/OUT OF RANGE [R TNK PROBE 7]B3-648401 - IRS INPUT DISAGREE [FQGC]
      

3. Do close out.