EIU-1 Output Bus A Fault

TASK 73-25-00-810-B41-A
EIU-1 Output Bus A Fault

1. Possible Causes

EIU-1 [1KS1]
wiring

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	MULTIMETER - STANDARD

B. Referenced Information

REFERENCE	DESIGNATION
AWM 313217
AMM 31-32-34-000-001	Removal of the CFDIU
AMM 31-32-34-400-001	Installation of the CFDIU
AMM 31-36-34-000-001	Removal of the Data Management Unit (DMU)
AMM 31-36-34-000-002	Removal of the FDIU/DMU (FDIMU)
AMM 31-36-34-400-001	Installation of the Data Management Unit (DMU)
AMM 31-36-34-400-002	Installation of the FDIU/DMU (FDIMU)
AWM 313723
AMM 31-38-34-000-001	Removal of the Data Loading Routing Box (DLRB)
AMM 31-38-34-400-001	Installation of the Data Loading Routing Box (DLRB)
AWM 315215
AMM 31-53-34-000-001	Removal of the Flight Warning Computer (FWC)
AMM 31-53-34-400-001	Installation of the Flight Warning Computer (FWC)
AWM 315435
AMM 31-55-34-000-001	Removal of the SDAC
AMM 31-55-34-400-001	Installation of the SDAC
AWM 341154
AMM 34-12-34-000-001	Removal of the ADIRU
AMM 34-12-34-400-001	Installation of the ADIRU
AWM 361111
AWM 361112
AMM 36-11-34-000-001	Removal of the BMC
AMM 36-11-34-400-001	Installation of the BMC
AWM 732531
AMM 73-25-34-000-802	Removal of the Engine Interface Unit (EIU)
AMM 73-25-34-400-802	Installation of the Engine Interface Unit (EIU)
AMM 73-25-34-710-802	Operational Test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS)

3. Fault Confirmation
Subtask 73-25-00-710-580-A ** ON A/C NOT FOR ALL

A. Do the operational test of the Engine Interface Unit (EIU) with the Centralized Fault Display System (CFDS) to confirm this fault. Refer to AMM 73-25-34-710-802.

4. Fault Isolation
Subtask 73-25-00-810-464-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Replace EIU-1 [1KS1] AMM 73-25-34-000-802 and AMM 73-25-34-400-802.
(a) Do the test given in Para. 3.
(2) If the fault continues, remove all components connected to EIU-1 (1KS1) connector (AB) contacts 5H/5K:
(a) Remove the Data Loading Routing Box (DLRB) (102TD) AMM 31-38-34-000-001.
(b) Remove the ADIRU-1 (1FP1), ADIRU-2 (1FP2) and ADIRU-3 (1FP3) AMM 34-12-34-000-001.
(c) Remove the two Flight Warning Computers (FWC) (1WW1) and (1WW2) AMM 31-53-34-000-001.
(d) Remove the two System Data Acquisition Concentrator (SDAC) (1WV1) and (1WV2) AMM 31-55-34-000-001.
(e) Remove the Data Management Unit (DMU) (1TV) or Flight Data Interface Unit (FDIU)/DMU Flight Data Interface and Management Unit (FDIMU) (10TV) AMM 31-36-34-000-001 or AMM 31-36-34-000-002.
(f) Remove the two Bleed Monitoring Computer (BMC) (1HA1) and (1HA2) AMM 36-11-34-000-001.
(g) Remove the Centralized Fault Display Interface Unit (CFDIU) (1TW) AMM 31-32-34-000-001.
(3) Do the test given in Para. 3.
(4) If the fault continues, use a MULTIMETER - STANDARD to do a check of wiring between EIU-1 (1KS1) and every component removed. Look for:
(a) Short-to-ground
(b) Wire-to-wire short
(c) Refer to AWM 732531 for common parts and DLRB
(d) Refer to AWM 341154 for all ADIRUs
(e) Refer to AWM 315215 for the two FWC
(f) Refer to AWM 315435 for the two SDAC
(g) Refer to AWM 313723 for DMU or FDIMU
(h) Refer to AWM 361111 for BMC-1
(i) Refer to AWM 361112 for BMC-2
(j) Refer to AWM 313217 for CFDIU
(k) Repair or replace wiring as necessary.
(l) Do the test given in Para. 3.
(5) If the fault does not continue, install one by one every components removed at step (2).
(a) After every component installation:
1 Do the test given in Para. 3.
(b) Install all components as follow:

NOTE: The component installation order can differ from order indicated:

1 Install the DLRB (102TD) AMM 31-38-34-400-001.
2 Install the ADIRU-1 (1FP1), ADIRU-2 (1FP2) and ADIRU-3 (1FP3) AMM 34-12-34-400-001.
3 Install both FWC (1WW1) and (1WW2) AMM 31-53-34-400-001.
4 Install the SDAC (1WV1) and (1WV2) AMM 31-55-34-400-001.
5 Install the DMU (1TV) or FDIU/DMU (FDIMU) (10TV) AMM 31-36-34-400-001 or AMM 31-36-34-400-002.
6 Install both BMCs (1HA1) and (1HA2) AMM 36-11-34-400-001.
7 Install the CFDIU (1TW) AMM 31-32-34-400-001.
(c) If the fault comes back, replace the component just installed.
(d) Do the test given in Para. 3.

5. Close-up
Subtask 73-25-00-860-186-A ** ON A/C NOT FOR ALL

A. Put the aircraft back to its initial configuration.
(1) Make sure that the work area is clean and clear of tools and other items.

[Rev.8 from Aug 2018] 2026.04.04 04:36:51 UTC