DOC AIRBUS | TSM A320FN1 Overlimit on Engine 1 or 2
TASK 77-00-00-810-850-A
N1 Overlimit on Engine 1 or 2
1. Possible Causes
2. Job Set-up Information
A. Referenced Information
3. Fault Confirmation
Subtask 77-00-00-710-125-A ** ON A/C NOT FOR ALL
Subtask 77-00-00-810-103-A ** ON A/C NOT FOR ALL
[Rev.8 from Aug 2018]
2026.04.04 04:37:32 UTC
N1 Overlimit on Engine 1 or 2
1. Possible Causes
2. Job Set-up Information
A. Referenced Information
| REFERENCE | DESIGNATION |
|---|---|
| AMM 31-32-00-860-001 | Procedure to Get Access to the SYSTEM REPORT/TEST Menu Page |
| AMM 71-00-00-710-006 | Minimum Idle Check |
| AMM 72-00-00-200-003 | Procedure After the Engine has Exceeded the Operational Limits |
| AMM 72-00-00-200-008 | Inspection/Check After the Engine has Exceeded the Operational Limits |
| AMM 73-21-10-000-001 | Removal of the Hydromechanical Unit (HMU) |
| AMM 73-21-10-000-002 | Removal of the Hydromechanical Unit (HMU) |
| AMM 73-21-10-400-001 | Installation of the Hydromechanical Unit (HMU) |
| AMM 73-21-10-400-002 | Installation of the Hydromechanical Unit (HMU) |
| AMM 73-21-60-000-001 | Removal of the Electronic Control Unit (ECU) |
| AMM 73-21-60-400-001 | Installation of the Electronic Control Unit (ECU) |
| AMM 73-21-60-740-007 | Correct Time Limited Faults (Non Asterisked) of the Engine Scheduled Maintenance Report |
| AMM 73-21-60-740-027 | Read the Specific Data Report |
| AMM 77-00-00-710-044 | Read of the N1,N2 and EGT Max Pointers |
Engine Overspeed DisplaySubtask 77-00-00-710-125-A ** ON A/C NOT FOR ALL
A. Test
(1) On the MCDU, read (if available) the DMC Max Value Report AMM 77-00-00-710-044 to note the max N1 value that was recorded during the event as well as the duration of the exceedence (if available from crew report).
If not, read or get the data from the DFDR or QAR.
Subtask 77-00-00-710-125-B ** ON A/C NOT FOR ALL (1) On the MCDU, read (if available) the DMC Max Value Report AMM 77-00-00-710-044 to note the max N1 value that was recorded during the event as well as the duration of the exceedence (if available from crew report).
If not, read or get the data from the DFDR or QAR.
A. Test
(1) On the MCDU, read (if available) the Specific Data Report AMM 73-21-60-740-027 to note the max N1 value that was recorded during the event as well as the duration of the exceedence (if available from crew report).
If not, read or get the data from the DFDR or QAR.
4. Fault Isolation(1) On the MCDU, read (if available) the Specific Data Report AMM 73-21-60-740-027 to note the max N1 value that was recorded during the event as well as the duration of the exceedence (if available from crew report).
If not, read or get the data from the DFDR or QAR.
Subtask 77-00-00-810-103-A ** ON A/C NOT FOR ALL
A. Do this procedure:
1 Read the Post Flight Report (PFR) or the Scheduled Maintenance Report (SMR) or Class 3 Report or the FADEC Last Leg Report and check for the FMV, HMU, N1 SNSR, VSV, PS3 failure messages AMM 73-21-60-740-007.
a If one or more message is present:
Subtask 77-00-00-810-103-C ** ON A/C NOT FOR ALL NOTE: The ECAM warning is triggered if the indicated N1 is greater than 102 percent.
(1) If the N1 overlimit is confirmed through the data contained in the DMC report(s) or AIDS data, or DFDR data and if the Crew reported the N1 indication flashing amber on the upper ECAM display unit: - Do the procedure after the engine has exceeded the engine operational limits AMM 72-00-00-200-003.
1 Read the Post Flight Report (PFR) or the Scheduled Maintenance Report (SMR) or Class 3 Report or the FADEC Last Leg Report and check for the FMV, HMU, N1 SNSR, VSV, PS3 failure messages AMM 73-21-60-740-007.
a If one or more message is present:
- do the troubleshooting related to the failure message(s).
- replace the HMU-1 [4000KC1] ( HMU-2 [4000KC2] ) AMM 73-21-10-000-001 and AMM 73-21-10-400-001.
- replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- Do a check of the FWC part number via the LRU identification screen on the MCDU AMM 31-32-00-860-001.
If the FWC part number is 350E017248685, the warning is spurious and should be disregarded. - no further maintenance action is required.
A. Do this procedure:
1 Read the Post Flight Report (PFR) or the Scheduled Maintenance Report (SMR) or Class 3 Report or the FADEC Last Leg Report and check for the FMV, HMU, N1 SNSR, VSV, PS3 failure messages AMM 73-21-60-740-007.
a If one or more message is present:
Subtask 77-00-00-710-258-A ** ON A/C NOT FOR ALL NOTE: The ECAM warning is triggered if the indicated N1 is greater than 104 percent.
(1) If the N1 overlimit is confirmed through the data contained in the Specific Data Report(s) AMM 73-21-60-740-027 or AIDS data, or DFDR data and if the Crew reported the N1 indication flashing amber on the upper ECAM display unit: - Do the procedure after the engine has exceeded the engine operational limits AMM 72-00-00-200-008.
1 Read the Post Flight Report (PFR) or the Scheduled Maintenance Report (SMR) or Class 3 Report or the FADEC Last Leg Report and check for the FMV, HMU, N1 SNSR, VSV, PS3 failure messages AMM 73-21-60-740-007.
a If one or more message is present:
- do the troubleshooting related to the failure message(s).
- replace the HMU-1 [4000KC1] ( HMU-2 [4000KC2] ) AMM 73-21-10-000-002 and AMM 73-21-10-400-002.
- replace the ECU [4000KS] AMM 73-21-60-000-001 and AMM 73-21-60-400-001.
- Do a check of the FWC part number via the LRU identification screen on the MCDU AMM 31-32-00-860-001.
If the FWC part number is 350E017248685, the warning is spurious and should be disregarded. - no further maintenance action is required.
B. Do a minimum idle check AMM 71-00-00-710-006.
(1) No additional maintenance action is required if the fault is not confirmed.
(2) Repeat the fault isolation procedure if the fault continues.
(1) No additional maintenance action is required if the fault is not confirmed.
(2) Repeat the fault isolation procedure if the fault continues.