05/06/21
Message Overview:
Message Description:
The Left APU Generator Contactor 2 (LAPC2) has failed.
Possible Causes:
- Left Auxiliary DC Power Contactor (LAPC2) (K149)
- Auxiliary Power Center Primary Logic (ALOG) (PCB11)
- Auxiliary Power Center (Aux DCPC) (A196)
- Left DC Power Center (L DCPC) (A35)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin:
- AW300-24-0024 - Electrical System - Troubleshooting Tips
- AW300-24-0137 - Y06 Electrical System Upgrade
Forum Articles/Infoservice/Newsletter: None
Quick Links:
| Removal of the DC Power Center (DCPC) | AMM 24-61-01-000-801 |
| Installation of the DC Power Center (DCPC) | AMM 24-61-01-400-801 |
| Functional Test of the DC Power Center (DCPC) | AMM 24-61-01-720-801 |
| Removal of the Auxiliary Power Contactor | AMM 24-61-13-000-801 |
| Installation of the Auxiliary Power Contactor | AMM 24-61-13-400-801 |
| Removal of the Auxiliary DC Power Center (Aux DCPC) | AMM 24-64-01-000-801 |
| Installation of the Auxiliary DC Power Center (Aux DCPC) | AMM 24-64-01-400-801 |
| Operational Test of the Auxiliary DC Power Center (Aux DCPC) | AMM 24-64-01-710-801 |
| Removal of the Auxiliary Power Center Primary-Logic | AMM 24-64-13-000-801 |
| Installation of the Auxiliary Power Center Primary-Logic | AMM 24-64-13-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Disconnect the Left Auxiliary DC Power Contactor K149 (LAPC2) connector located in the L DCPC. Do visual inspection of the connector and associated wiring for any loose pins and/or damaged wire.
- If inspection is satisfying, continue with next step.
- If inspection is not satisfying, go to step 8.
- Do wiring check of the following wires:
From To Results AUX DCPC conn. A196P3 - pin m L DCPC conn. A35P5 - pin m AUX DCPC conn. A196P3 - pin E L DCPC conn. A35P5 - pin E AUX DCPC conn. A196P3 - pin F L DCPC conn. A35P5 - pin F AUX DCPC conn. A196P3 - pin B L DCPC conn. A35P5 - pin B - If wiring check is satisfying, continue with next step.
- If wiring check is not satisfying, repair wiring.
- Do wiring check of the following wires:
From To Results L DCPC conn. A35J5 - pin m K149 conn (P-side) - pin 6 L DCPC conn. A35J5 - pin E K149 conn (P-side) - pin 1 L DCPC conn. A35J5 - pin F K149 conn (P-side) - pin 3 L DCPC conn. A35J5 - pin B K149 conn (P-side) - pin 2 - If wiring check is satisfying, continue with next step.
- If wiring check is not satisfying, go to step 8.
- Verify Left Auxiliary DC Power Contactor K149 (LAPC2) coils by measuring the resistances at the contactor connector (P-side) as per the following table:
Coils Expected Values Results (Pick-up) Pin 1 and Pin 2 between 4.5 Ω and 6.5 Ω (Hold) Pin 2 and Pin 3 between 260 Ω and 280 Ω - If the verification is satisfying, continue with next step.
- If the verification is not satisfying, replace the defective Auxiliary DC Power Contactor.
NOTE: It is important to not skip this verification before proceeding with the interchange at step 5. A short of one of the 2 coils will result with a blowing of a fuse on the Auxiliary Power Center Primary Logic PC11.
- Interchange the Left Auxiliary DC Power Contactor K149 (LAPC2) with the Right Auxiliary DC Power Contactor K148 (RAPC2). Is the fault message still present?
- If YES, continue with next step.
- If NO, replace the defective Auxiliary DC Power Contactor.
- Replace the Auxiliary Power Center Primary Logic PC11. Is the fault message still present?
- If YES, continue with next step.
- If NO, do close out.
- Replace the Aux DCPC. Is the fault message still present?
- If YES, continue with next step.
- If NO, do close out.
- Replace the Left DCPC.
- Do close out.