Loss of the 28VDC SHED ESS Bus 801PP

TASK 24-60-00-810-810-A
Loss of the 28VDC SHED ESS Bus 801PP

1. Possible Causes

CNTOR-DC SHED ESS BUS [8PH]
RELAY-B HYD PUMP CTL [21XE]
wiring
RELAY-STAT INV CTL [6XB]
C/B-EMER/SHED/CNTOR/SPLY [1PH]

2. Job Set-up Information
A. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 24-00-00-810-803-A	Circuit Breaker Tripped and/or C/B TRIPPED Warning
AMM 23-71-00-710-001	Operational Test of the CVR and the CVR Channel Recording
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AMM 24-41-00-862-002	De-energize the Aircraft Electrical Circuits Supplied from the External Power
ASM 246201
AWM 246202
AMM 24-62-55-000-001	Removal of the DC Shed Essential Bus Contactor
AMM 24-62-55-400-001	Installation of the DC Shed Essential Bus Contactor
AMM 31-60-00-860-001	EIS Start Procedure

3. Fault Confirmation
Subtask 24-60-00-860-064-A

A. Job Set-up
(1) Aircraft Maintenance Configuration
(a) Energize the aircraft electrical circuits
AMM 24-41-00-861-002.
(b) Do the EIS start procedure (Upper ECAM DU and lower ECAM DU only)
AMM 31-60-00-860-001.

Subtask 24-60-00-710-068-A

B. Test
(1) Do this test:

ACTION	RESULT
On the ECAM control panel: push the ELEC key to get the ELEC page.	On the upper ECAM display unit: the ELEC DC ESS BUS SHED warning comes into view.

(2) Do the operational test of the CVR and the CVR channel recording (test of the CVR only) AMM 23-71-00-710-001.

4. Fault Isolation
Subtask 24-60-00-865-056-A

A. Table of the circuit breakers used in this procedure:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C ALL
106VU	EMER/SHED/CNTOR/SPLY	1PH	C07

Subtask 24-60-00-810-059-A

B. If the test confirms the fault:

Do a check of the status of the circuit breaker (1PH).

(1) If the circuit breaker (1PH) is closed:

Do a check for 28VDC between pins B/5 and B/3 of the DC SHED ESS BUS contactor (8PH) ASM 246201.

(a) If there is 28VDC on the contactor (8PH):

Replace the CNTOR-DC SHED ESS BUS [8PH] AMM 24-62-55-000-001 and AMM 24-62-55-400-001.

(b) If there is no 28VDC on the contactor (8PH):

Do a check for 28VDC at pin A/B2 of the B hydraulic pump control relay (21XE).

1 If there is 28VDC on the relay (21XE):

Replace the RELAY-B HYD PUMP CTL [21XE] .

a If the fault continues:

Do a check and repair the wiring between:
. pin A/B3 of the B hydraulic pump control relay (21XE) and pin B/3 of the DC SHED ESS BUS contactor (8PH),
. pin B/5 of the DC SHED ESS BUS contactor (8PH) and the ground point or terminal block ASM 246201 and AWM 246202.

2 If there is no 28VDC on the relay (21XE):

Do a check for 28VDC at pin A/B2 of the static inverter control relay (6XB).

a If there is 28VDC on the relay (6XB):

Replace the RELAY-STAT INV CTL [6XB] .
. If the fault continues:
Do a check and repair the wiring between pin A/B3 of the static inverter control relay (6XB) and pin A/B2 of the B hydraulic pump control relay (21XE) ASM 246201.

b If there is no 28VDC on the relay (6XB):

Do a check and repair the wiring between the:
. pin A/F of the DC ESS BUS supply contactor (4PC) and pin 1 of the EMER/SHED/ CNTOR/SPLY circuit breaker (1PH),
. pin A/2 of the EMER/SHED/CNTOR/SPLY circuit breaker (1PH) and pin A/B2 of the static inverter control relay (6XB)
ASM 246201 and AWM 246202.

(2) If the circuit breaker is open:

Do the procedure (Ref. TSM TASK 24-00-00-810-803).

(a) If the fault continues:

Replace the C/B-EMER/SHED/CNTOR/SPLY [1PH] .

Subtask 24-60-00-710-069-A

C. Do this test to make sure that the system operates correctly:

ACTION	RESULT
1.On the ECAM control panel: push the ELEC key to get the ELEC page.	On the upper ECAM display unit: no warning comes into view.
	On the lower ECAM display unit: the normal configuration comes into view.
2.On the overhead control and indicating panel 21VU: push the RCDR/GND CTL pushbutton switch.	on the pushbutton switch, the ON legend comes on make sure that you can hear the conversations from the CVR microphone in the headset.

5. Close-up
Subtask 24-60-00-860-065-A

A. Put the aircraft back to its initial configuration.
(1) On the ECAM control panel, set the UPPER DISPLAY and LOWER DISPLAY potentiometers to OFF.
(2) De-energize the aircraft electrical circuits
AMM 24-41-00-862-002.

[Rev.8 from Aug 2018] 2026.04.04 04:26:58 UTC