AFT XFER OFF SCHED
(Caution)

AFT XFER OFF SCHED (Caution) is displayed when the total wing fuel quantity is less than 3000 lbs + 3 times the aft tank quantity and the aft tank is not empty.

• AFT XFER switch (S2) is not set to AUTO
• Fuel Control Panel (AP5)
• AFT Fuel Tank Probes (TU1AFT) (TU1AFTCMP) (TU2AFT) (TU2AFTCMP)
• Fuel Management Quantity and Gauging Computer (FMQGC) (A47)
• Associated Wiring

Advisory Wire/Service Bulletin:

• SB 700-28-034 - Fuel Re-circulation System

Forum Articles/Infoservice/Newsletter: None

NOTES:

• This message is not applicable to the Global 5000.
• The FMQGC is part of the NFF initiative and rarely is the cause of the issue.
• As viewed in CAIMS, the Probe Status "GOOD PROBE" indicates the probe is communicating with FMQGC and the probe is reporting a capacitance within a nominal range (between full dry and full wet). The OMS may report the Probe Status as "GOOD PROBE", yet a dry capacitance check per the AMM may find a probe out of AMM limits. The only way to verify if a probe is reporting accurately is to do the Dry Capacitance check IAW AMM task 28−41−00−760−801 Capacitance Test of the Fuel Quantity Probes.
  

1. Verify the AFT XFER switch is set to AUTO.
2. Are any of these CAS messages AFT XFER FAIL (Caution), or AFT XFER FAULT (Advisory), or FUEL COMPUTR FAIL (Caution), or FUEL COMPUTR FAULT (Advisory) posted ?

   1. If YES, Investigate and troubleshoot these messages first.
   2. If NO, then go to step 3.

3. Perform the fuel transfer operational test of the AFT- tank Manual transfer system (AMM 28-22-00-710-803.
   NOTE: The CAIMS, FMQGC, LRU TEST menu can be used to test the pumps and valves of the AFT transfer system.

   1. If the system checks OK, then go to step 6 and perform the fuel capacitance test on the AFT fuel tank fuel probes.
   2. If the AFT XFER OFF SCHED (Caution) CAS message is displayed, continue with next step.

4. Gain access to the Fuel Computer (FMQGC) (A47).
5. Remove the FMQGC. Inspect the tray, connector and wiring for proper installation, damage or contamination. Re-install the FMQGC making sure it is fully secured into place. Is the fault still present?

   1. If YES, then continue with the next step.
   2. If NO, do close out.

6. Perform the dry capacitance test for the AFT fuel tank probes and record values on the following data entry form. Did the AFT fuel tank capacitance test of the fuel probes pass?

   1. If YES, continue with the next step.
   2. If NO, inspect the faulty probe(S) for contamination or corrosion and rectify/replace as necessary (TU1AFT), (TU2AFT), (TU1CMPAFT) and (TU2CMPAFT).

7. Perform a wiring check of the interface between the AFT tank fuel probes and the FMQGC.

   1. If No defects are found, continue with the next step.
   2. If wiring defects are found, repair defective wiring as required.
      NOTE: You can attempt to move or shake the wiring at the connection points along the line to detect any intermittent connections.

8. Perform a visual inspection of the AFT tank fuel probes. Look for signs of contamination or corrosion. Make sure that the electrical connections are secured properly.

   1. If defects are found, rectify/repair as required.
   2. If no defects are found, continue with the next step.

9. Replace FMQGC (A47).
10. Do close out.