DOC AIRBUS | TSM A320FLoss of the N1 Vibration Indication on Engine 1
1. Possible Causes
· N1 trim balance probe
· wiring
· EVMU ( 2EV )
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 31-60-00-860-001 EIS Start Procedure
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
Ref. AMM 71-00-20-000-040 Removal of the Power Plant
Ref. AMM 71-00-20-400-040 Installation of the Power Plant
Ref. AWM 71-51-04
Ref. AWM 71-51-10
Ref. ASM 77-32-02
Ref. AWM 77-32-03
Ref. AMM 77-32-34-000-041 Removal of the Engine Vibration Monitoring Unit (EVMU)
Ref. AMM 77-32-34-400-041 Installation of the Engine Vibration Monitoring Unit (EVMU)
Ref. AMM 77-32-34-710-041 Operational Check of EVMU through CFDS
70-00-00-03-13 STANDARD PRACTICES - ENGINE - GENERAL - TASK SUPPORTING
DATA
N1 Trim Balance Probe (Engine 1) SHEET 1
Installation without Voltage Divider Harness Assembly SHEET 1
Installation with Voltage Divider Harness Assembly SHEET 1
Figure 77(IAE)-30-00-991-00100-A / SHEET 1/1 - N1 Trim Balance Probe (Engine 1) not printed, as
per printing preferences
Figure 77(IAE)-30-00-991-00500-A / SHEET 1/1 - Installation without Voltage Divider Harness
Assembly not printed, as per printing preferences
Figure 77(IAE)-30-00-991-00600-A / SHEET 1/1 - Installation with Voltage Divider Harness Assembly
not printed, as per printing preferences
3. Fault Confirmation
Subtask 77-30-00-860-062-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/1 pushbutton switch.
(3) Do the EIS start procedure Ref. AMM 31-60-00-860-001 .
Subtask 77-30-00-710-080-A
B. Test
(1) On the panel 50VU, push the ENG FADEC GND PWR/1 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 1 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.
NOTE: During this engine run, check on ECAM-SD ENGINE page that N1 VIB is displayed XX in amber.
(6) Do a shutdown of the engine 1 by the discontinued start, restart and shutdown procedure Ref.
AMM 71-00-00-710-018 .
(7) Read the LAST LEG REPORT of the FADEC (1A and 1B) menu on the MCDU
(Ref. TSM 70-00-00-03) .
(a) Make a record of the maintenance message.
(b) Make a record of the channel FADEC 1A or FADEC 1B which found the fault.
(8) Fully decrease the brightness of the MCDU screen (display off).
4. Fault Isolation
(Ref. Fig. N1 Trim Balance Probe (Engine 1) SHEET 1) (Ref. Fig. Installation without Voltage Divider Harness
Assembly SHEET 1) (Ref. Fig. Installation with Voltage Divider Harness Assembly SHEET 1)
Subtask 77-30-00-810-088-A
A. Check of the Voltage Divider Assembly
NOTE: A hot engine can increase the resistance measurements on the probes, therefore make sure that
the engine has cooled down (at least 2 hours after shutdown) before you do the checks.
(1) If the voltage divider harness assembly is not installed:
· Continue with this procedure at step 4.B.
(Ref. Fig. Installation without Voltage Divider Harness Assembly SHEET 1)
(2) If the voltage divider harness assembly is installed:
· Continue with this procedure at step 4.C.
(Ref. Fig. Installation without Voltage Divider Harness Assembly SHEET 1)
Subtask 77-30-00-810-066-A
B. If the test gives the maintenance message ENG1 SPEED SENSOR 4000EV:
· Disconnect the electrical connector (2EV-AA) from the EVMU (2EV).
· At the electrical connector (2EV-AA), do a check of the resistance between pins 8B and 7A (25 and 55
ohms or 75 and 95 ohms) Ref. ASM 77-32-02.
(1) If the resistance between the pins 8B and 7A is not between 25 and 55 ohms or between 75 and 95
ohms:
· Do a check of the electrical resistance of the trim balance probe between pins 7 and 8 at terminal
block 4000VS Ref. AWM 71-51-10.
(a) If the resistance between pins 7 and 8 at the terminal block 4000VS is not between 25 and 55
ohms or between 75 and 95 ohms:
· Replace the engine Ref. AMM 71-00-20-000-040 and Ref. AMM 71-00-20-400-040 for
replacement of the N1 trim balance probe .
(b) If the resistance between the pins 7 and 8 at the terminal block 4000VS is between 25 and 55
ohms or between 75 and 95 ohms:
· Do a check and repair the wiring from the EVMU (2EV) to the terminal block 4000VS Ref.
AWM 77-32-03 , Ref. AWM 71-51-04 and Ref. AWM 71-51-10.
(2) If the fault continues or if the resistance between pins 8B and 7A is not between 25 and 55 ohms or
between 75 and 95 ohms:
· Do the operational test of the engine vibration monitoring unit with the CFDS Ref.
AMM 77-32-34-710-041 .
(3) If the fault continues:
· Replace the EVMU ( 2EV ) Ref. AMM 77-32-34-000-041 and Ref. AMM 77-32-34-400-041 .
Subtask 77-30-00-810-089-A
C. If the test gives the maintenance message ENG1 SPEED SENSOR 4000EV:
· Disconnect the electrical connector (2EV-AA) from the EVMU (2EV).
· At the electrical connector (2EV-AA), do a check of the resistance between pins 8B and 7A (2380 and
2490 ohms) Ref. ASM 77-32-02.
(1) If the resistance between the pins 8B and 7A is not between 2380 and 2490 ohms:
· Do a check of the electrical resistance at the electrical adapter 407VC-A between pins 17 and 18
(2380 and 2490 ohms) Ref. AWM 77-32-03.
(a) If the resistance at the electrical adapter 407VC-A between pins 17 and 18 is not between 2380
and 2490 ohms:
· Do a check of the electrical resistance of the trim balance probe between pins 7 and 8 at
terminal block 4000VS Ref. AWM 71-51-10.
1 If the resistance is between 75 and 95 ohms:
· Remove the voltage divider harness assembly.
· Do a check and repair the wiring from the electrical adapter 407VC-A to the terminal
block 4000VS Ref. AWM 71-51-04 and Ref. AWM 71-51-10.
2 If the resistance is between 25 and 55 ohms:
· Do a check of the correct installation of the voltage divider harness assembly.
· Do a check and repair the wiring from the electrical adapter 407VC-A to the terminal
block 4000VS Ref. AWM 71-51-04 and Ref. AWM 71-51-10.
3 If the resistance is not between 25 and 55 ohms or between 75 and 95 ohms:
· Replace the engine Ref. AMM 71-00-20-000-040 and Ref. AMM 71-00-20-400-040 for
replacement of the N1 trim balance probe .
(b) If the resistance at the electrical adapter 407VC-A between pins 17 and 18 is between 2380 and
2490 ohms:
· Do a check and repair the wiring from the electrical connector (2EV-AA) to the electrical
adapter 407VC-A Ref. AWM 77-32-03.
(2) If the fault continues or if the resistance between the pins 8B and 7A is not between 2380 and 2490
ohms:
· Do the operational test of the engine vibration monitoring unit with the CFDS Ref.
AMM 77-32-34-710-041 .
(3) If the fault continues:
· Replace the EVMU ( 2EV ) Ref. AMM 77-32-34-000-041 and Ref. AMM 77-32-34-400-041 .
Subtask 77-30-00-710-081-A
D. Do the test given in Para. 3.
5. Close-up
Subtask 77-30-00-860-063-A
A. Put the aircraft back to its initial configuration.
(1) Do the EIS stop procedure Ref. AMM 31-60-00-860-002 .
(2) On the panel 50VU, push the ENG FADEC GND PWR/1 pushbutton switch.
(3) De-energize the aircraft electrical circuits
Ref. AMM 24-41-00-862-002 . [Rev.6 from Feb 2017] 2026.04.04 04:37:52 UTC