ARINC Out Bus Wraparound Dual Channels (TX2A/TX1B) Failure

TASK 73-21-00-810-893-A
ARINC Out Bus Wraparound Dual Channels (TX2A/TX1B) Failure

1. Possible Causes

HARNESS-FAN, WF02 [4218KS]
HARNESS-FAN, WF01 [4217KS]
aircraft wiring
[4000KS]

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

REFERENCE	QTY	DESIGNATION
No specific	1	MULTIMETER - STANDARD
No specific	1	PLIERS - JAWED, SOFT

B. Referenced Information

REFERENCE	DESIGNATION
TSM TASK 71-00-00-810-834-A	General Troubleshooting Guidelines for Additional Troubleshooting Information
TSM TASK 71-00-00-810-835-A	Component and Harness Intermittent Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
AWM 228604
AWM 242207
AWM 242208
AMM 24-41-00-861-002	Energize the Aircraft Electrical Circuits from the External Power
AWM 315214
AWM 316217
AWM 316218
AMM 70-70-00-910-803	SPOP 6 - Cleaning of the Contact Points and Wiring Harnesses
AMM 71-13-00-010-802	Opening of the Fan Cowl Doors
AMM 71-13-00-410-802	Closing of the Fan Cowl Doors
AMM 73-21-01-000-801	Removal of the Electronic Engine Control (EEC)
AMM 73-21-01-400-801	Installation of the Electronic Engine Control (EEC)
AMM 73-21-61-000-802	Removal of the Electronic Engine Control (EEC) Wiring Harness (WF01)
AMM 73-21-61-400-802	Installation of the Electronic Engine Control (EEC) Wiring Harness (WF01)
AMM 73-21-62-000-802	Removal of the EEC Wiring Harness (WF02)
AMM 73-21-62-400-802	Installation of the EEC Wiring Harness (WF02)
AWM 732526
AWM 732527
AWM 732529
AWM 732530
EEC Wiring Harnesses
Pylon Junction Box Connections
ARINC Output Bus Wiring Schematic
ARINC Output Bus Wiring Schematic

3. Fault Confirmation
Subtask 73-21-00-710-146-A ** ON A/C NOT FOR ALL

A. Energize the FADEC of the engine that has a fault report.
(1) Energize the aircraft electrical circuits AMM 24-41-00-861-002.
(2) On the ENG section of maintenance panel 50VU:
(a) Release the FADEC GND PWR/1(2) pushbutton switch (the ON legend comes on).

NOTE: After the FADEC is energized, wait ten seconds before you start the test. If you do not wait ten seconds, the interactive mode stops the EEC self-test and this can cause spurious faults.

(3) On MCDU screen, check if the fault is displayed on ground scanning report.

NOTE: The Electronic Engine Control (EEC) has detected that the channel A ARINC Output Bus 2 and channel B ARINC Output Bus 1 circuits are shorted. The ARINC Output Bus 1 and 2 circuits are between the EEC and the Engine Interface Unit (EIU). The EEC is located on the fan case at the 2 o'clock position.

Refer to the general troubleshooting guidelines for additional troubleshooting information (Ref. TSM TASK 71-00-00-810-834).
Refer to the component and harness intermittent troubleshooting procedure for guidance troubleshooting intermittent faults (Ref. TSM TASK 71-00-00-810-835).

(4) If the maintenance message does not come back, examine the harnesses and electrical connectors as described in the component and harness intermittent fault isolation procedure (Ref. TSM TASK 71-00-00-810-835).
(a) If no problems are found, return the engine to service. Monitor the engine for reoccurring maintenance message.
(5) If the maintenance message comes back (hard fault), go to the Para. Fault Isolation.

4. Fault Isolation

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE AFTER SHUTDOWN. THE ENGINE CAN STAY HOT FOR A LONG TIME. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

WARNING: REFER TO THE MSDS FOR ALL MATERIAL USED AND THE MANUFACTURER'S SAFETY INSTRUCTIONS FOR ALL EQUIPMENT USED. IF YOU DO NOT OBEY THIS WARNING, INJURY CAN OCCUR.

CAUTION: MAKE SURE YOU REMOVE ELECTRICAL POWER FROM THE EEC BEFORE YOU REMOVE THE ELECTRICAL CONNECTORS. IF YOU DO NOT OBEY THIS INSTRUCTION, DAMAGE TO THE EEC CAN OCCUR.

Subtask 73-21-00-810-165-A ** ON A/C NOT FOR ALL

A. If there is confirmation of the fault:
(1) Open the fan cowl doors AMM 71-13-00-010-802.
(2) Examine the WF02 (4218KS) and WF01 (4217KS) harnesses, connectors P1 (4000KS-P1), P2 (4000KS-P2) - EEC (4000KS) and connectors P402 (402VC-A), P403 (403VC-A) - pylon junction box, for problems which are possible between the EEC (4000KS) and the pylon junction box.
(a) Inspect for harnesses damage.
(b) Inspect for loose or damaged connectors.

NOTE: Loose connectors must be disconnected and examined for further wear or damage.

(c) If a problem is found with the harnesses or connectors:
1 Replace the HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802, or
2 Replace the HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802.
3 Do the test given in Para. 3.
(3) If no problems are found with the harnesses or the fault continues, use a PLIERS - JAWED, SOFT to disconnect the electrical connectors P1 (4000KS-P1), P2 (4000KS-P2) from the EEC (4000KS) and connectors P402 (402VC-A), P403 (403VC-A) from the pylon junction box.
(a) Examine the pins and sockets (contacts) for alignment and damage. Look for contacts pushed rearward into the connector face. Replace parts as necessary.
(b) Clean the contacts with contact cleaner and clean cloth per SPOP 6. Blow dry with air (at less than 30 psi) across connector face AMM 70-70-00-910-803.
(c) Reconnect the electrical connectors P1 (4000KS-P1), P2 (4000KS-P2) to the EEC (4000KS) and connectors P402 (402VC-A), P403 (403VC-A) to the pylon junction box.
(d) Do the test given in Para. 3.
(4) If the fault continues:
(a) Disconnect the electrical connectors P1 (4000KS-P1), P2 (4000KS-P2) from the EEC (4000KS) and connectors P402 (402VC-A), P403 (403VC-A) from the pylon junction box. Use a MULTIMETER - STANDARD to test the ARINC Output Bus 2 channel A circuit and the ARINC Output Bus 1 channel B circuit in the harnesses. Refer to Table 1 and Table 2. Look for:
1 Wire-to-wire shorts
2 Shorts to ground
3 Continuity (less than 5 ohms resistance).

NOTE: A short to ground is found when the resistance is less than 100 000 (100K) ohms.

Table 1: ARINC Output Bus 2 Channel A Connector Contacts

WF02 (4218KS) Harness P1 (4000KS-P1) EEC (4000KS) Connector Contacts	WF02 (4218KS) Harness P402 (402VC-A) Pylon Junction Box Connector Contacts
c	36
B	18

Table 2: ARINC Output Bus 1 Channel B Connector Contacts

WF01 (4217KS) Harness P2 (4000KS-P2) EEC (4000KS) Connector Contacts	WF01 (4217KS) Harness P403 (403VC-A) Pylon Junction Box Connector Contacts
W	35
v	34

(b) If a problem is found with the harnesses or connectors:
1 Replace the HARNESS-FAN, WF02 [4218KS] AMM 73-21-62-000-802 and AMM 73-21-62-400-802, or
2 Replace the HARNESS-FAN, WF01 [4217KS] AMM 73-21-61-000-802 and AMM 73-21-61-400-802.
3 Do the test given in Para. 3.
(5) If no problems are found with the harnesses or the fault continues:
(a) Disconnect electrical connectors (402VC-A) and (403VC-A).
(b) Do a check of the aircraft wiring containing the ARINC Output Bus 2 channel A circuit and the ARINC Output Bus 1 channel B circuit from the aircraft computers to the pylon junction box at contact 36 and 18 of electrical connector (402VC) and at contact 35 and 34 of electrical connector (403VC):
1 For fault of ENG 1: refer to AWM 732527, AWM 732529, AWM 228604, AWM 242207, AWM 315214 and AWM 316217.
2 For fault of ENG 2: refer to AWM 732526, AWM 732530, AWM 228604, AWM 242208, AWM 315214 and AWM 316218.
3 Look for:

Wire-to-wire shorts
Shorts to ground
Continuity (less than 5 ohms resistance).

NOTE: A short to ground is found when the resistance is less than 100 000 (100k) ohms.

4 If you find damage:
a Replace or repair aircraft wiring .
b Reconnect all connectors.
c Do the test given in Para. 3.
(6) If the fault continues:
(a) Replace [4000KS] AMM 73-21-01-000-801 and AMM 73-21-01-400-801.
(b) Make sure that all connectors are reconnected.
(c) Do the test given in Para. 3.

5. Close-up
Subtask 73-21-00-860-085-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.
(a) Close the fan cowl doors AMM 71-13-00-410-802.

[Rev.8 from Aug 2018] 2026.04.04 04:36:41 UTC