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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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07/17/23

Message Overview:

Message Name:

OPN/SHRT/OUT OF RANGE

Message Code:

B3-007128

Associated CAS:

None

Reporting LRU: L TNK PR 8/COMP
System Description: 28-41-00
Schematic Diagram: 28-41-00
Wiring Diagram: 28-41-13

Message Description:

The FQGC has detected a discrepancy in the Left Tank fuel quantity probe 8 or Compensator probe circuit.

  • If the left tank quantity is replaced with magenta dashes, the fault is within the L probe 8 circuit. If the left tank quantity is shown, the fault is within the L compensator circuit.
  • The fault can be triggered by the presence of water in the probe.

Possible Causes:

  • Water Contamination
  • Fuel Quantity Gauging Computer (FQGC) (A57)
  • Left Fuel Quantity Probe With Compensator (No. 8) (MT13)
  • Associated Wiring

Troubleshooting Tips:

Advisory Wire/Service Bulletin:

  • AW300-28-0118 - No Fault Found Initiative: Fuel Quantity and Gauging Computer (FQGC)
  • AW300-28-0138 - Fuel Tank Sumping
  • SB 100-28-06 - Fuel management and quantity gauging system (FMQGS) - Replacement and Relocation of Fuel Quantity Probes No. 5, and Replacement of Fuel Quantity Probes No. 8 with Compensator to correct Gauging System Faults
  • SB 100-28-08 - Rework-Wing Tank-Addition Of Sealant To Facilitate Water Drainage From Wing Fuel Tanks And Prevent Erratic Fuel Indications

Forum Articles/Infoservice/Newsletter: None

  • 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).
  • When sumping water from affected fuel tank it is preferable to have the fuel probe 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, do not move aircraft for at least 2 hours before sumping.

Fuel Probes Capacitance
EMPTY TANK FULL TANK OUT OF RANGE
PROBE VALUE pf PROBE VALUE pf VALUE pf
1 29 1 53 <25.88 or >65.1
2 29.1 2 56.8 <25.88 or >65.1
3 29 3 56.8 <25.88 or >65.1
4 34.1 4 67.4 <30.83 or >77.16
5 40.8 5 80.1 <37.13 or >91.93
6 63.8 6 127.1 <58.66 or >146.01
7 59.7 7 118.4 <54.8 or >136.2
8 79.5 8 158.6 <72.94 or >181.43
9 63.7 9 126.9 <58.66 or >146.01
10 66 10 128.2 <121.39 or >138.42

Quick Links:

Pressure Refueling AMM 12-11-01-650-801
Suction Defueling AMM 12-11-09-650-801
Drain Water from the Fuel Tank AMM 28-10-00-680-801
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
Installation of the Fuel Quantity Computer AMM 28-41-01-400-801
Removal of the Fuel Quantity Probe AMM 28-41-13-000-801
Installation of the Fuel Quantity Probe AMM 28-41-13-400-801
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
Wiring - Maintenance Practices - ALL SPM 20-12-00-02
Wire Repair - Maintenance Practices - ALL SPM 20-12-10-02
Electrical Connectors - Maintenance Practice - ALL SPM 20-20-00-02

Troubleshooting Recommendations:

  1. If the MDC fault code is in the FAULT HISTORY and the left fuel tank indication is not dashed, no action is required, but it is recommended to sump fuel from the left tank in case water was the cause of the failure.
  2. If the MDC fault code is in the CURRENT FAULT, and the left fuel tank quantity indication is replaced with magenta dashes, do the Capacitance Check of the Fuel Probes.

    1. If the reading for L PR08 is under 72.94pF, check wiring from FQGC to left probe 8. If wiring is found serviceable, replaced probe.
    2. If the reading for L PR08 is over 181.43pF, sump at least 2 gallons of fuel from the left fuel tank or until no water is found. If fault continues, go to next step.

  3. If the MDC fault code is in the CURRENT FAULT, and the left fuel tank quantity indication is available, do the following do the Capacitance Check of the Fuel Probes.

    1. If the reading for L PR10 is under 121.39pF, check wiring from FQGC to left compensator. If wiring is found serviceable, replaced probe.
    2. If the reading for L PR10 is over 138.42pF, sump at least 2 gallons of fuel from the left fuel tank or until no water is found. If fault continues, go to next step.

  4. 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.

  5. Defuel the aircraft. If fault continues, go to next step.
  6. Access the left tank probe 8/COMP.

    1. Check probe for loose electrical connections.
    2. Clean probe (AMM 28-41-13-160-801).
    3. If fault continues, go to next step.

  7. Check wiring from FQGC to left tank probe 8/COMP. If wiring is found serviceable, replace left tank fuel probe 8/COMP.
  8. If fault continues, replace FQGC.
  9. Do close out.

collect_probe

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