CB TRIP DC FEED
(Caution)

Message displayed if one or more of the following conditions is met;

• DC BUS 1 Feeder 1, 2, 3 or 4 tripped
• DC ESS BUS Feeder 1, 2, 3 or 4 tripped
• DC BATT BUS Feeder 1, 2, 3 or 4 tripped
• DC BUS 2 Feeder 1, 2, 3 or 4 tripped

• Aircraft system(s) failure
• DC BUS failure
• DCPC component(s)
• Associated Wiring

Advisory Wire/Service Bulletin: None

Forum Articles/Infoservice/Newsletter: None

CAUTION: If a circuit breaker opens, do not try to close it before you correct the problem that caused it to open. You can cause damage to the aircraft wiring and equipment.

1. Open CAIMS on the PMAT. Inspect the ACTIVE FAULTS as per AMM Task. Check for any DC system or DCPC related active faults.

   1. If there are active fault posted, troubleshoot them first. Active faults not listed in the drop down menu below can found in 'Troubleshooting' - 'By CAIMS'
   2. If there are no active faults, continue with next step
      Select an CAIMS Message:2460402DCP - DCPC SPDA DC BUS 1 FEEDER CARD A22460403DCP - DCPC SPDA DC BUS 2 FEEDER CARD A32460404DCP - DCPC SPDA DC ESS BUS FEEDER CARD A42460405DCP - DCPC SPDA DC BAT BUS FEEDER CARD A5

2. Access the EMS CDU Signboard Menu as per AMM Task. Select 'CDU OUT'. Select labels '110-137' and scroll the pages until you can see labels 134 and 135. Refer to the following table and record which bit(s) is (are) set to 1 in the data field:
   

   Label	Bit	Feed	Trip=1 Normal=0
   134	20	DC BUS 1 Feed 1
   134	21	DC BUS 1 Feed 2
   134	22	DC BUS 1 Feed 3
   134	23	DC BUS 1 Feed 4
   134	24	DC ESS BUS Feed 1
   134	25	DC ESS BUS Feed 2
   134	26	DC ESS BUS Feed 3
   134	27	DC ESS BUS Feed 4
   135	15	DC BATT BUS Feed 1
   135	16	DC BATT BUS Feed 2
   135	17	DC BATT BUS Feed 3
   135	18	DC BATT BUS Feed 4
   135	19	DC BUS 2 Feed 1
   135	20	DC BUS 2 Feed 2
   135	21	DC BUS 2 Feed 3
   135	22	DC BUS 2 Feed 4

3. Disconnect the DCPC affected Feed output recorded in step 3. Disconnect the associated SPDA feed input. Do a continuity check between the affected DCPC output and the SPDA input. Make sure you check for short circuits to ground and short circuits between the power and return. Were any defects found with the wiring interface?
   CB TRIP DC FEED IMAGE

   1. If YES, repair defective wiring as required.
   2. If NO, continue with next step.

4. Reconnect the DCPC but leave the affected SPDA disconnected and apply power to the A/C. Is the CAS message still present?

   1. If YES, continue with next step.
   2. If NO, go to step 7.

5. Access the DCPC logic assembly. Swap the affected DC Feeder card recorded in step 3. Did the fault follow the card?

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

6. Replace affected SPDA. On the MRA, mention the exact name of the feed that was tripped.
7. Do close out.