Message Name:

LH OR RH SIDE OF AIRCRAFT UNPOWERED

One side of the aircraft (LH or RH) has no power upon electrical power application. Synoptic page reflects this condition.

• Left DC Power Center (DCPC) (A35)
• Right DCPC (A36)
• L DCPC Primary Logic Card (PCB-3)
• R DCPC Primary Logic Card (PCB-4)
• L DCPC Protection Card (PCB-1)
• R DCPC Protection Card (PCB-2)
• L DCPC Battery Diode PCB
• R DCPC Battery Diode PCB
• L Battery Contactor (K73)
• R Battery Contactor (K74)
• Left Secondary Power Center (A37)
• Right Secondary Power Center (A38)
• Left Circuit Breaker Panel (CBP1)
• Right Circuit Breaker Panel (CBP2)
• Associated Wiring

Advisory Wire/Service Bulletin:

• AW300-24-0024 - Electrical System - Troubleshooting Tips:
• AW300-24-0284 - Metallic Particles Found in the Left Direct Current Power Center (LDCPC) Battery Diode PCB Area

Forum Articles/Infoservice/Newsletter: None

1. Gain access to the affected DCPC (LH or RH) in the aft equipment bay.
2. Perform a visual inspection of the terminal studs on the affected DCPC. Look for signs of electrical arcing or burn marks. Make sure all fasteners on the terminal studs are properly torqued.

   1. If defects are found, take the necessary measures to rectify.
   2. If no defects or apparent signs of damage are found, continue with next step.

3. While power is applied to the aircraft, perform a 28 VDC voltage check on the T4 (Main Bus) and T5 (Essential Bus) terminals.

   1. If 28 VDC is present, go to step 9.
   2. If 28 VDC is missing, continue with next step.

4. Swap the DCPC Primary Logic Cards (PLC) between DCPC (PCB-3 with PCB-4). Did the fault transfer to the other side?

   1. If YES, replace the defective PLC.
   2. If NO, continue with next step.

5. Swap the DCPC Protection cards (PCB-1 with PCB-2). Did the fault transfer to the other side?

   1. If YES, replace the defective Protection card.
   2. If NO, continue with next step.

6. Swap the LH and RH Battery diode cards. Did the fault transfer to the other side?

   1. If YES, replace the defective card.
   2. If NO, continue with next step.

7. Swap the LH DCPC K73 relay with the RH DCPC K74 relay. Did the fault transfer to the other side?

   1. If YES, replace the defective relay.
   2. If NO, continue with next step.

8. Replace the affected DCPC.
9. Access the RH or LH side Cockpit Circuit Breaker Panel (CCBP) (affected side). Perform a 28 VDC voltage check on the Left (Right) Main Bus, the Essential Bus and the Battery Bus.

   1. If 28 VDC is present, perform a wiring check inside the CCBP. Repair as required.
   2. If one or more busses does not have 28 VDC present, continue with next step.

10. Gain access to the affected Secondary Power Center (LH or RH).
11. Perform a visual inspection of the terminal studs on the affected Secondary Power Center. Look for signs of electrical arcing or burn marks. Make sure all fasteners on the terminal studs are properly torqued.

    1. If defects are found, take the necessary measures to rectify.
    2. If no defects or apparent signs of damage are found, continue with next step.

12. While power is applied to the aircraft, perform a 28 VDC voltage check on the T4 (Main Bus) and T5 (Essential Bus) terminals and connector A37P2-T (Left BATT Bus) or A38P2-M (Right BATT Bus).

    1. If 28 VDC is present, continue with next step.
    2. If 28 VDC is missing, perform a wiring check between the same side DCPC and the Secondary Power Center.

13. Perform a 28 VDC voltage check on the T1 (Main Bus) and T2 (Main Bus) terminals and connector A37P2-P (Left BATT Bus) or A38P2-P (Right BATT Bus).

    1. If voltage is present, perform a wiring check between the affected Secondary power center and the same side CCBP. Repair as required.
    2. If voltage is not present, replace the defective Secondary Power center.

14. Do close out.