02/25/21
Message Overview:
Message Description:
The Left Main Fuse (LMAINF) connecting the Left Essential Bus to the Left Secondary Power Center, located in the Left DC Power Center, has blown.
Possible Causes:
- Left Main Fuse (LMAINF) (F1)
- Left DC Power-Center Protection (LPROT) (PCB1)
- Left DC Power Center (L DCPC) (A35)
- Left Secondary Power Center (LSPC) (A37)
- Left Circuit Breaker Panel (LCBP) (CBP1)
- Associated Wiring
Troubleshooting Tips:
Advisory Wire/Service Bulletin: None
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 DC Power-Center Protection | AMM 24-61-77-000-801 |
| Installation of the DC Power-Center Protection | AMM 24-61-77-400-801 |
| Removal of the DC Power-Center Fuses | AMM 24-61-79-000-801 |
| Installation of the DC Power-Center Fuses | AMM 24-61-79-400-801 |
| Removal of the Secondary Power Center (SPC) | AMM 24-62-01-000-801 |
| Installation of the Secondary Power Center (SPC) | AMM 24-62-01-400-801 |
| Removal of the Cockpit Circuit-Breaker Panel (CCBP) | AMM 24-65-01-000-801 |
| Installation of the Cockpit Circuit-Breaker Panel (CCBP) | AMM 24-65-01-400-801 |
| Wiring - Maintenance Practices - ALL | SPM 20-12-00-02 |
| Wire Repair - Maintenance Practices - ALL | SPM 20-12-10-02 |
Troubleshooting Recommendations:
- Disconnect both batteries and the External DC power.
- Inspect Left DCPC (A35), external and internal, for any signs of burning and any foreign object that could have caused a short circuit.
- If inspection is okay, continue with next step.
- If inspection is not okay, replace defective L DCPC (A35) and go to step 4.
- Remove, inspect and measure the Left Main Fuse (F1) located in the Left DCPC (A35). Is the Fuse good?
- If YES, go to step 4.
- If NO, replace defective fuse and continue with next step.
NOTE: AIPC has to be follow to ensure proper Fuse Part Number. An incorrect fuse current rating might cause major damages to the aircraft.
- Inspect Left SPC (A37), external and internal, for any signs of burning and any foreign object that could have caused a short circuit.
- If inspection is okay, continue with next step.
- If inspection is not okay, replace defective L SPC (A37) and continue with next step.
- Inspect Left CBP (CBP1), external and internal, for any signs of burning and any foreign object that could have caused a short circuit.
- If inspection is okay, continue with next step.
- If inspection is not okay, replace defective L CBP (CBP1) and continue with next step.
- Disconnect and do wiring check of the following power feeders:
From To Results L DCPC - Stud T4 L SPC - Stud T4 L SPC - Stud T2 L CBP - Stud T1 - If check is okay, continue with next step.
- If check is not okay, repair/replace defective feeder.
- Swap the Left DC Power-Center Protection (PCB1) with the Right DC Power-Center Protection (PCB2). Is the fault message still present?
- If YES, contact your FSR for a deeper investigation.
- If NO, replace the defective DC Power-Center Protection.
- Do close out.
