DOC AIRBUS | TSM A320FLoss of the N1 Overspeed Discrete Output from the Fan Speed Probe on Engine 2
1. Possible Causes
· wiring
· EEC ( 4000KS )
2 Job Set-up Information
A. Referenced Information
REFERENCE DESIGNATION
Ref. AMM 24-41-00-861-002 Energize the Aircraft Electrical Circuits from the External Power
Ref. AMM 24-41-00-862-002 De-energize the Aircraft Electrical Circuits Supplied from the External
Power
Ref. AMM 31-60-00-860-002 EIS Stop Procedure
Ref. AMM 71-00-00-710-018 Discontinued Start, Restart and Shutdown Procedures
Ref. AMM 71-00-00-710-043 Normal Engine Automatic Start Procedure
Ref. AMM 71-00-00-710-047 Normal Engine Manual Start Procedure
REFERENCE DESIGNATION
Ref. AMM 71-13-00-410-010 Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
Ref. AMM 71-50-00-210-010 Wire Harness Visual Inspection - All Power Plant Electrical Cables
Ref. AMM 71-50-00-220-010 Wire Continuity Check - All Power Plant Electrical Cables
Ref. AMM 73-22-34-000-010 Removal of the Electronic Engine Control (EEC)
Ref. AMM 73-22-34-400-010 Installation of the Electronic Engine Control (EEC)
Ref. ASM 73-25-13
Ref. AMM 77-11-00-860-010 Change over the N1 Rotational Speed Indicating Probe Harness Leads
400VS-1, 400VS-2, 400VS-5 and 400VS-6
Ref. AMM 78-32-00-410-010 Closing of the Thrust Reverser Halves
3. Fault Confirmation
Subtask 73-22-00-860-170-A
A. Job Set-Up
(1) Energize the aircraft electrical circuits Ref. AMM 24-41-00-861-002 .
(2) On the panel 50VU, release the ENG FADEC GND PWR/2 pushbutton switch.
Subtask 73-22-00-710-212-A
B. Test
(1) On the panel 50VU, push the ENG FADEC GND PWR/2 pushbutton switch and release it again.
NOTE: This action resets the FADEC memory.
(2) Adjust the brightness of the MCDU screen.
(3) Push the INIT mode key. The INIT page comes into view.
(4) Enter a new flight number.
(5) Start the engine 2 by the normal engine automatic start procedure Ref. AMM 71-00-00-710-043 or
the normal engine manual start procedure Ref. AMM 71-00-00-710-047 .
NOTE: Operation of the engine for at least 3 minutes erases the LAST LEG REPORT related to the
last flight and the new fault is recorded in the EEC LAST LEG REPORT.
(6) Do a shutdown of the engine 2 by the discontinued start, restart and shutdown procedure Ref.
AMM 71-00-00-710-018 .
(7) Read the LAST LEG REPORT of the FADEC (2A and 2B) menu on the MCDU (Ref. 70-00-00 Page
Block 301 Task Supporting Data).
(a) Make a record of the maintenance message.
(b) Make a record of the channel FADEC 2A or FADEC 2B which found the fault.
(8) Fully decrease the brightness of the MCDU screen (display off).
4. Fault Isolation
Subtask 73-22-00-810-137-A
A. If the test gives the maintenance message A1/A5 HARNESS DISCRETE:
· change over the N1 rotational speed indicating probe harness leads Ref. AMM 77-11-00-860-010 .
NOTE: Connect the harness related to the defective channel to a spare connection.
(1) If the fault continues:
· read the fault code shown on the FLIGHT DATA and GROUND DATA of the FADEC (2A and 2B)
menu on the MCDU (Ref. 70-00-00 Page Block 301 Task Supporting Data)
· make a record of the fault code.
(a) If the FADEC 2A menu gives the fault code ODISCF:
· examine the wiring from the terminal block (4000VS) of the fan speed probe to the EEC
(4000KS) Ref. AMM 71-50-00-210-010 and Ref. ASM 73-25-13.
1 If the fault continues:
· do a check of the wiring from the terminal block (4000VS) of the fan speed probe to the
EEC (4000KS):
. pins 1, 2 to pins J2/L, d Ref. AMM 71-50-00-220-010 .
(b) If the FADEC 2B menu gives the fault code ODISCF:
· examine the wiring from the terminal block (4000VS) of the fan speed probe to the EEC
(4000KS) Ref. AMM 71-50-00-210-010 and Ref. ASM 73-25-13.
1 If the fault continues:
· do a check of the wiring from the terminal block (4000VS) of the fan speed probe to the
EEC (4000KS):
. pins 5, 6 to pins J8/L, d Ref. AMM 71-50-00-220-010 and Ref.
ASM 73-25-13.
(2) If the fault continues:
· replace the EEC ( 4000KS ) Ref. AMM 73-22-34-000-010 and Ref. AMM 73-22-34-400-010 .
Subtask 73-22-00-710-213-A
B. Do the test given in Para. 3.
5. Close-up
Subtask 73-22-00-860-171-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
Ref. AMM 31-60-00-860-002 .
(2) On the panel 50VU, push the ENG FADEC GND PWR/2 pushbutton switch.
(3) De-energize the aircraft electrical circuits Ref. AMM 24-41-00-862-002 .
(4) Make sure that the thrust reverser halves 461AL and 462AR are closed Ref.
AMM 78-32-00-410-010 .
(5) Make sure that the fan cowls 447AL and 448AR are closed Ref. AMM 71-13-00-410-010 . [Rev.6 from Feb 2017] 2026.04.04 04:36:20 UTC