Message Name:

CMPL - COMPENSATOR/WRG

Message Code:

284466BPK

Associated CAS:

FUEL QTY DEGRADED
(Advisory)

CMPL FMQGS COMPENSATOR/WRG FAULT shows when the COMPENSATOR (CMPL) has failed open, shorted, out of range or is contaminated.

• Compensator (CMPL) (C7)
• Fuel Management Quantity and Gauging Computer (FMQGC) (A47)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

NOTE: 

• 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. Using CAIMS, check for FMQGC Fault message.

   1. If FMQGS COMPUTER CH A AUTOCAL #1/WRG FAULT is displayed, go to step 16.
   2. If CMPL FMQGS COMPENSATOR/WRG FAULT is indicated, go to step 12.
   3. If 2 or more probes faults are indicated, continue with next step.

2. Sump the tank, check for Water Contamination in the fuel, sample about a gallon or more.

   1. If water is found in fuel sample, drain and access tank to clean.
   2. If fuel sample is clean, continue with next step.

3. Using CAIMS, check compensator and probes for stable capacitance values and record values on the following data entry form. Move the FMQGC box and harness.

   1. If capacitance values are out of range or unstable (small variation is acceptable), re-rack the FMQGC and ensure it is completely engaged with connector A47BP1.
   2. If capacitance values are good, suspect an intermittent fault and continue with next step.

4. Using CAIMS, LRU Test Page, check for compensator stable capacitance value. Ensure no intermittent connection of the excitation line wiring and connectors (A47BP1, CJ413, CP413 and LTP2).

   1. If capacitance values are out of range or unstable (small variation is acceptable), go to step 6.
   2. If capacitance values are good, suspect an intermittent fault and continue with next step.

5. Using the alternate method, check for intermittent excitation line connectors (A47BP1, CJ413, CP413 and LTP2), using a digital AC Voltmeter. Measure the excitation voltage between the center pin and the connector body at connector LTP2.

   1. If voltage is 5.3 VAC (approx.) and stable, suspect an intermittent fault. Repair as required and do close out.
   2. If voltage is 3.2 VAC (approx. or less), continue with next step.

6. Perform continuity check for shield termination between connector LTP2 and A47BP1.

   1. If there is no continuity, repair defective wiring as required and do close out.
   2. If there is continuity, continue with next step.

7. Check FMQGC connectors A47BP1 and A47BJ1 for security and proper assembly.

   1. Center pin 1 is not recessed, it is crimped properly and secured to shield pin 1S.
   2. Shield pin 1S is crimped properly and locked to connector A47BP1.
   3. Ensure center contact socket/pin has good friction and they are not bent.

8. Check connector CJ413, CP413 and LTP2 for security and proper assembly.

   1. Shield cable nut (jam nut) is secured and not cross-threaded.
   2. Center pin is corrosion free and soldered properly to the cable.
   3. Proper cable shield termination to connector.

9. With the FMQGC removed, check for open circuit between the center conductor and the shield at connector LTP2. The resistance value should be very high (>100 Mega Ohms range) and stable.

   1. If fault indication is gone, do close out.
   2. If fault remains, continue with next step.

10. Defuel the aircraft and drain the tanks. Check for water droplets or biological growth on access cover, probe and in surrounding area. Access connectors between LTJ2 and CMPL.

    1. If water contamination is found, clean tank and ventilate to dry it out, remove probe and clean in alcohol bath before re-installation.
    2. If Tank/Probe are clean, continue with next step.

11. Check security of terminals for excitation line wiring and connector between LTJ2, TU2L and CMPL.

    • Ensure shield termination is crimped properly and secured to probe clamping
    • Ensure conductor lugs are crimped properly and torque on probe terminals
    • Ensure terminals are corrosion free
    • Measure Excitation Voltage at Probe, 5.3 VAC (aprox.)

    1. If wiring checks are not good, repair defective wiring as required or probe terminal and do close out.
    2. If wiring checks are good, continue with next step.

12. Using CAIMS, LRU Test Page, check probe CMPL capacitance value.

    1. If capacitance value is good, suspect an intermittent fault and go to step 14.
    2. If capacitance value is out of range or unstable (small variation is acceptable), continue with next step.

13. Check probe CMPL for contamination.

    1. If probe is contaminated, clean probe and do close out.
    2. If probe is clean, continue with next step.

14. Perform wiring check between CMPL compensator and FMQGC.
    NOTE: No wire splicing or insulation repair allowed inside the fuel tanks.

    1. If wiring checks are not good, repair defective wiring as required and do close out.
    2. If wiring checks are good, continue with next step.

15. Replace compensator CMPL.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

16. Reset FMQGC power in a last chance to clear the fault.

    1. If system checks are good, do close out.
    2. If fault remains, continue with next step.

17. Replace the FMQGC.
18. Do close out.