DOC AIRBUS | TSM A320FNacelle Component and Harness Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
TASK 71-00-00-810-843-A
Nacelle Component and Harness Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
1. Possible Causes
A. Referenced Information
3. Fault Confirmation
Subtask 71-00-00-710-101-A ** ON A/C NOT FOR ALL
Subtask 71-00-00-810-109-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:41:31 UTC
Nacelle Component and Harness Troubleshooting Procedure for Guidance Troubleshooting Intermittent Faults
1. Possible Causes
- wiring harness
[4000KS]
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| AMM 70-70-00-910-801 | SPOP 430 - Application of Electrical Contact Enhancer for Wiring Harnesses |
| AMM 70-70-00-910-803 | SPOP 6 - Cleaning of the Contact Points and Wiring Harnesses |
| 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) |
Subtask 71-00-00-710-101-A ** ON A/C NOT FOR ALL
A. Not Applicable
4. Fault IsolationNOTE: The fault is not confirmed on the ground by performing the test required in the fault confirmation paragraph. Faults are sometimes generated by electrical transients or similar events without the aircraft system being faulty. If the confirmation test result is "TEST OK" or equivalent, no further action is required (unless specified in the fault isolation procedure).
The aircraft may be dispatched. It is recalled that the Trouble Shooting Manual (TSM) has been designed to isolate/troubleshoot hard faults. However depending on the airlines organization, the following can be applied to intermittent faults:
The aircraft may be dispatched. It is recalled that the Trouble Shooting Manual (TSM) has been designed to isolate/troubleshoot hard faults. However depending on the airlines organization, the following can be applied to intermittent faults:
- If "TEST OK" (fault not confirmed) dispatch the aircraft, then perform a monitoring of the reported symptom on the following flights by checking:
* The previous leg report
* The PFR/previous PFRs (if available)
* The log book of the previous flights.
Subtask 71-00-00-810-109-A ** ON A/C NOT FOR ALL
A. Do as follows to isolate any intermittent maintenance messages caused by a problem in the component or wiring.
(1) At the second occurrence of the same phenomenon (even through the test is still OK), find all the connectors and wiring harness segments involved in the fault isolation procedure of the relevant TSM task and do as follows:
(a) Examine the wiring harness, electrical connectors and backshells for possible problems between the EEC and the involved component.
1 Look for wiring harness damage.
2 Look for loose or damaged electrical connectors.
3 Look for loose or damaged backshells.
4 Do a check of the mating connector for alignment and damage. Look for contacts pushed rearward toward the connector face. If you find a pin with one bend that is less than 20 degrees, it can be straightened. You can straighten the bent pin by using a spare mating socket as a tool.
5 Do a check of the connectors for fretting or contamination. If fretting or contamination is found, clean the contacts with contact cleaner AMM 70-70-00-910-803.
6 Replace wiring harness as necessary.
(2) At the third occurrence of the same phenomenon (even through the test is still OK), find all the connectors and wiring harness segments involved in the fault isolation procedure of the relevant TSM task and do as follows:
(a) Do a harness check:
1 Do a check and make sure that the mating sockets and pins for each connector have a good interference fit as follows:
1 Replace the applicable component.
2 Replace the applicable wiring harness .
3 Replace
(c) In this case, as for all LRUs removed from the aircraft, AIRBUS recommends providing shop people or suppliers with data related to the removal: PFR, test result, troubleshooting data (if available).
(1) At the second occurrence of the same phenomenon (even through the test is still OK), find all the connectors and wiring harness segments involved in the fault isolation procedure of the relevant TSM task and do as follows:
(a) Examine the wiring harness, electrical connectors and backshells for possible problems between the EEC and the involved component.
1 Look for wiring harness damage.
2 Look for loose or damaged electrical connectors.
3 Look for loose or damaged backshells.
4 Do a check of the mating connector for alignment and damage. Look for contacts pushed rearward toward the connector face. If you find a pin with one bend that is less than 20 degrees, it can be straightened. You can straighten the bent pin by using a spare mating socket as a tool.
5 Do a check of the connectors for fretting or contamination. If fretting or contamination is found, clean the contacts with contact cleaner AMM 70-70-00-910-803.
6 Replace wiring harness as necessary.
(2) At the third occurrence of the same phenomenon (even through the test is still OK), find all the connectors and wiring harness segments involved in the fault isolation procedure of the relevant TSM task and do as follows:
(a) Do a harness check:
1 Do a check and make sure that the mating sockets and pins for each connector have a good interference fit as follows:
- Make a test lead approximately 6 in. (152.40 mm) long with a socket at one end and the same size (gage) pin at the other. Make sure that you use the correct size for the pin or socket to be tested. Damage to the connector will result if you test a socket with a pin that is too large. To achieve the best results, use a new test lead for each electrical connector.
- To test the sockets, insert the pin from the test lead into each socket of the connector in the suspect circuit. Make sure that there is some resistance or friction felt when you install and remove the pin from the test lead from each socket.
- To test the pins, insert the pin from the connector of the suspect circuit into the socket on the test lead. Make sure that there is some resistance or friction felt when you install and remove the socket from the test lead from each pin.
- Repeat the steps with the remaining connector contacts between the EEC and the component as necessary. If the test finds that there is a loose interference fit, this can be the cause of the intermittent fault. The wiring harness or component that has a connector with a loose interference fit condition should be replaced.
- A temporary repair for contacts with a loose interference fit can be done by using an electrical contact enhancer per SPOP 430 AMM 70-70-00-910-801.
1 Replace the applicable component.
2 Replace the applicable wiring harness .
3 Replace
(c) In this case, as for all LRUs removed from the aircraft, AIRBUS recommends providing shop people or suppliers with data related to the removal: PFR, test result, troubleshooting data (if available).