W DOC AIRBUS | AMM A320F

Engine Trim Balancing via Menu Mode [CFML]

TASK 73-29-00-740-808-A
Engine Trim Balancing via Menu Mode

ZONE: 400
1. Reason for the Job
The Engine Trim Balance function allows the operator to calculate a fan trim balance solution using vibration data from previous flight legs or ground runs. The operator may select either the one-shot or advanced trim methods.
If a solution is reached, the operator is instructed to replace currently installed trim balance weights with the arrangement provided by the solution in order to reduce engine vibration. The new solution may be saved in Electronic Engine Control Non Volatile Memory (EEC NVM).
2. Job Set-up Information
 A. Work Zones and Access Panels
ZONE/ACCESS
ZONE DESCRIPTION
400
POWER PLANT, NACELLES AND PYLONS
 B. Referenced Information
REFERENCE
DESIGNATION
TASK 24-41-00-861-002-A
Energize the Aircraft Electrical Circuits from the External Power
TASK 24-41-00-861-002-A-01
Energize the Aircraft Electrical Circuits from the APU
TASK 24-41-00-861-002-A-02
Energize the Aircraft Electrical Circuits from Engine 1(2)
TASK 24-41-00-862-002-A
De-energize the Aircraft Electrical Circuits Supplied from the External Power
TASK 24-41-00-862-002-A-01
De-energize the Aircraft Electrical Circuits Supplied from the APU
TASK 24-41-00-862-002-A-02
De-energize the Aircraft Electrical Circuits Supplied from the Engine 1(2)
TASK 31-32-00-860-012-A
Procedure to Get Access to the SYSTEM REPORT/TEST/ENG Page
TASK 71-00-00-710-813-A
Vibration Check
TASK 71-00-00-750-804-A
One Shot Trim Balance
TASK 71-00-00-750-805-A
Advanced Trim Balance
TASK 73-29-00-710-804-A
Weight Configuration (Menu Mode)
F Special Functions Menu (Screen 2)
F Engine Balancing Submenu (Screen 3)
F Existing Weights (Screen 4)
F One Shot Trim Balance (Screen 5)
F Engine Balance In Progress Format (Screen 6)
F One Shot Trim Balance Solution (Screen 7)
F Balance Weights Calculation Error (Screen 8)
F Balance Weights Saved (Screen 9)
F Failed Weight Configuration Change (Screen 10)
F Balance Coefficient Selection (Screen 11)
F Specific Coefficients Calculation Error (Screen 12)
F Advanced Trim Balance Function (Screen 13)
F Engine Balance Calculation Error Format (Screen 14)
F Advanced Trim Balance Solution (Screen 15)
F Main Menu (Screen 1)
F Function Terminated (Screen 16)
3. Job Set-up
Subtask 73-29-00-861-068-A
A. Energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-861-002).
Subtask 73-29-00-865-079-A
B. Make sure that this(these) circuit breaker(s) is(are) closed:
PANELDESIGNATIONFINLOCATION
** ON A/C ALL
FOR FIN: 4020KM1 (POWER PLANTDEMOUNTABLE, ENGINE 1)
49VUENGINE/1/FADEC A/AND EIU 12KS1A04
121VUENGINE/ENG1/FADEC B/AND EIU 14KS1R40
FOR FIN: 4020KM2 (POWER PLANTDEMOUNTABLE, ENGINE 2)
49VUENGINE/2/FADEC A/AND EIU 22KS2A05
121VUENGINE/ENG2/FADEC B/AND EIU24KS2R41
Subtask 73-29-00-860-094-A
C. Aircraft Maintenance Configuration
   (1) On ENG panel 115VU:
     (a) Make sure that the ENG MASTER switch 1(2) is set to OFF.
     (b) Make sure that the ENG/MODE rotary selector switch is set to NORM.
   (2) On the ENG section of maintenance panel 50VU:
     (a) Release the FADEC GND PWR1(2) pushbutton switch. The ON legend of this pushbutton switch 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 the left or right MCDU, get the SYSTEM REPORT/TEST/ENG page (Ref. AMM TASK 31-32-00-860-012).
4. Procedure
Subtask 73-29-00-710-083-A
A. Engine Balancing Test (Menu Mode)
   (1) Two options are available for engine trim balancing:
  • One Shot Engine Trim Balance Menu Mode function
  • Advanced Engine Trim Balance Menu Mode function
     (a) Choose the step B. One Shot Engine Trim Balance Menu Mode function to compute engine trim balancing using the most recent flight leg or ground run vibration data with generic trim coefficients.
     (b) Choose the step C. Do the Advanced Engine Trim Balance Menu Mode function to compute engine trim balancing using selectable flight leg and/or ground run vibration data with either generic or specific trim coefficients. This option also allows the user to calculate new trim coefficients if enough valid data is present.
Subtask 73-29-00-710-070-A
B. Do the One-Shot Engine-Trim-Balance Menu-Mode function.
NOTE: The EEC will not enter the menu mode (interactive mode) after an enquire command from the Centralized Fault Display System (CFDS) when any of the following conditions are set:
  • N2 more than ten percent or invalid
  • Engine not off
  • Engine not in default start state
  • Throttle Lever Angle (TLA) at idle or invalid
  • Aircraft in the air
  • MASTER lever ON or invalid
  • BITE command code input label invalid.
NOTE: The EEC will abort the engine balancing and display the FUNCTION TERMINATED screen when any of the following conditions becomes set:
  • N2 more than ten percent or invalid
  • Engine not in default start state
  • TLA not at idle or invalid
  • MASTER lever ON or invalid
  • You enter in the interactive mode of the other channel.
NOTE: When the return key is selected on the MCDU when an ENGINE BALANCING submenu subscreen is displayed, the EEC aborts the function and display the engine balancing submenu screen.
F Engine Balancing Submenu (Screen 3)
NOTE: If one of the following conditions occurs while menu mode is active, the Menu Mode session will be exited directly, without displaying a specific screen:
  • RETURN key selected on main menu screen
  • Channel in Menu Mode is not the active channel.
  • Invalid BITE command or invalid equipment code received by EEC
  • A LOGOFF condition received by EEC.
  • Engine start detected whereas function requiring idle speed (as idle test, vibration ground run) is not active.
  • Selected mach more than 0.12 or invalid
  • Aircraft indicates in air.
   (1) The one-shot engine trim balance Menu Mode function allows the operator to perform a fan (1-plane) balance using the most recent flight leg or ground run vibration data with the generic trim coefficients.

ACTION
RESULT
1.Initialize Menu Mode on the applicable engine and EEC, by selecting FADEC XY (x=Eng position, y=channel number).

2.From the Menu Mode main menu, select the key adjacent to SPECIAL FUNCTIONS.
The SPECIAL FUNCTIONS Menu is displayed.
3.Select the key adjacent to ENGINE BALANCING.
The ENGINE BALANCING submenu is displayed.
4.Select the key adjacent to BALANCE ENGINE.
The EXIST BALANCE WGTS screen is displayed.
5.You need to identify the fan balance weights configuration display on the MCDU and correct it if necessary by following the AMM task: (Ref. AMM TASK 73-29-00-710-804).
The weight configuration display on the MCDU is corresponding the physical weight installed on the engine.
6.Select the key adjacent to ONE SHOT.
The ONE SHOT TRIM BALANCE screen is displayed.
NOTE: The vibration amplitudes and phases for various speed ranges are displayed for the most recent flight leg or ground run. If there is no data available "---" is displayed.
The data collection method is displayed as "LEG" (flight leg) or "GND" (ground run).
7.On the ONE SHOT TRIM BALANCE screen, select the key adjacent to CALC.
NOTE: The CALC selection is not displayed if there is not enough data available to calculate a trim solution.
The engine balance in progress screen is displayed. The one shot trim solution utilizes generic coefficients.
  • If a solution is available, the calculated weight solution is displayed.
  • If a solution is unavailable, the BALANCE WEIGHTS CALCULATION ERROR screen is displayed. Reattempt one-shot trim balance. If reattempt is unsuccessful, attempt with additional vibration data or utilize alternate trim balancing function.
  • If the weight configuration is changed before selecting CALC without storing into NVM, the message CALCULATION ERROR will show up.
8.If solution is available, review the calculated vibration reduction, weight part numbers, and bolt hole locations (Ref. AMM TASK 71-00-00-750-804).

Remove the current trim weights and apply weight part numbers to the bolt hole locations displayed.

Select the key adjacent to SAVE WEIGHTS to store the weights to EEC NVM.
NOTE: When Save weights button is selected, EEC saves weights configuration into NVM (EEC memory). If Save weights button is selected without installing the proposed weights solution, there is a discrepancy between the aircraft and EEC configuration.
  • If the weight data is successfully stored to NVM, the BALANCE WEIGHTS SAVED screen is displayed.

  • If the Save Weights button is pressed and the data was unsuccessfully stored to NVM due to a failure or corruption in the NVM, the FAILED WEIGHT CONFIGURATION CHANGE screen is displayed. Verify no EEC NVM faults are present and all Menu Mode conditions are satisfied. Reattempt weight configuration change.
Subtask 73-29-00-710-084-A
C. Do the Advanced Engine-Trim-Balance Menu-Mode function
NOTE: The EEC will not enter the menu mode (interactive mode) after an enquire command from the CFDS when any of the following conditions are set:
  • N2 more than ten percent or invalid
  • Engine not off
  • Engine not in default start state
  • TLA not at idle or invalid
  • Aircraft in the air
  • MASTER lever ON or invalid
  • BITE command code input label invalid.
NOTE: The EEC will abort the engine balancing and display the FUNCTION TERMINATED screen when any of the following conditions becomes set:
  • N2 more than ten percent or invalid
  • Engine not in default start state
  • TLA not at idle or invalid
  • MASTER lever ON or invalid
  • You enter in the interactive mode of the other channel.
NOTE: When the Return key is selected on the MCDU when an ENGINE BALANCING submenu subscreen is displayed, the EEC aborts the function and display the engine balancing submenu screen.
F Engine Balancing Submenu (Screen 3)
NOTE: If one of the following conditions occurs while menu mode is active, the Menu Mode session will be exited directly, without displaying a specific screen:
  • RETURN key selected on main menu screen
  • Channel in Menu Mode is not the active channel.
  • Invalid BITE command or Invalid equipment code received by EEC
  • A LOGOFF condition received by EEC
  • Engine start detected whereas function requiring idle speed (as Idle Test, Vibration Ground Run) is not active.
  • Selected Mach more than 0.12 or invalid
  • Aircraft indicates in air.
   (1) The advanced engine-trim-balance Menu Mode function allows the operator to perform a fan (1-plane) balance using selectable flight leg or ground run vibration data with either generic or specific trim coefficients. The operator also has the option to calculate new specific coefficients if vibration criteria is met. Using specific coefficients may offer a more accurate fan balance solution.

ACTION
RESULT
1.Initialize Menu Mode on the applicable engine and EEC, by selecting FADEC XY (x=eng position, Y=channel number).

2.From the Menu Mode main menu select the key adjacent to SPECIAL FUNCTIONS.
The SPECIAL FUNCTIONS menu is displayed.
3.Select the key adjacent to ENGINE BALANCING.
The ENGINE BALANCING submenu is displayed.
4.Select the key adjacent to BALANCE ENGINE.
The EXIST BALANCE WGTS screen is displayed.
5.You need to identify the fan balance weights configuration display on the MCDU and correct it if necessary by following the AMM task: (Ref. AMM TASK 73-29-00-710-804).
The weight configuration display on the MCDU is corresponding the physical weight installed on the engine.
6.Select the key adjacent to ADVANCED METHOD.
The BALANCE COEFFICIENT SELECTION screen is displayed.
7.Select the key adjacent to the balance coefficient to be used in the trim balance calculation (see step D. for more details):
  • To Calculate New Coefficients
  • For Generic Coefficients
  • For Specific Coefficients (if displayed).
Limitation: when "Calculate New Coefficients" button is pressed, the solution uses generics instead of specifics coefficients, when CALC button is pressed on the next screen.
Mitigation: After pressing "Calculate New Coefficients" button, press Return on next screen.
F Advanced Trim Balance Function (Screen 13)
ENGINE BALANCING screen is displayed. Come back on BALANCE COEFFICIENT SELECTION screen to select "Specific coefficients" button. In this case, specific coefficients will be correctly used to calculate the trim balance solution.
NOTE: The SELECT SPECIFIC option will not be displayed if the EEC does not have specific coefficients previously calculated.
To calculate the first time the specific coefficients, use the Calculate New coefficients button.
If Calculate New Coefficients was selected but criteria were not met to successfully calculate a solution, the following screen is displayed. Select RETURN.
ENGINE BALANCING screen is displayed. Come back on BALANCE COEFFICIENT SELECTION screen and select alternate coefficient (step 5) and contact CFM engineering.

If CALCULATE NEW COEFFICIENTS was selected and new coefficients were successfully calculated, do the following steps:
  • Select RETURN.
  • Select Specific Coefficients in order to be able to use the new specific coefficients in trim solution calculation.

Once the coefficients have been selected, the ADVANCED TRIM BALANCE screen is displayed.
NOTE: The vibration amplitudes and phases for various speed ranges are displayed for the last 10 flight legs (0-9, where 0 is the most recent). If there is no data available "---" is displayed.
The eleventh and last page displayed is the average vibration data.
Next page and previous page button should be used to navigate between the flight legs.
The data collection method is displayed as "LEG" (flight leg), "GND" (ground run), or "AVG" (average vibration).
8.On the ADVANCED TRIM BALANCE screen, select the key adjacent to CALC.
NOTE: The CALC selection is not displayed if there is not enough data available to calculate a trim solution. If a solution is not available, a possible cause is the inability for the FADEC to capture and store N1 speed bins because of anyone of the following faults:
  • Control Learning Area NVM (code 0244)
  • N1 Soft Sensor Shift (code 0339)
  • N1 Sensor Out of Range (codes 0340, 0449, 0451)
  • No.1 Bearing Accelerometer Out of Range (codes 0208, 0209, 0337)
  • Fan Position Indication Failed (code 0391).
If you identify one of these faults, do the applicable TSM procedures to correct it before you try to do the trim balance.
The IN PROGRESS screen is displayed. The trim solution utilizes the coefficients previously selected (generic, specific, or calculated):
  • If a solution is available, the calculated weights and estimated reduction is displayed.
  • If a solution is unavailable, the BALANCE WEIGHTS CALCULATION ERROR screen is displayed. Reattempt advanced trim balance. If reattempt is unsuccessful, attempt with alternate coefficients or additional vibration data.
9.If solution is available, review the calculated vibration reduction, weight part numbers, and bolt hole locations (Ref. AMM TASK 71-00-00-750-805).

Remove the current trim weights and apply weight part numbers to the bolt hole locations displayed.

Select the key adjacent to SAVE WEIGHTS to store the weights to EEC NVM.
NOTE: When Save weights button is selected, EEC saves weights configuration into NVM (EEC memory). If Save weights button is selected without installing the proposed weights solution, there is a discrepancy between the aircraft and EEC configuration.
  • If the weight data is successfully stored to NVM, the BALANCE WEIGHTS SAVED screen is displayed.
    F Balance Weights Saved (Screen 9)

  • If the Save Weights button (5L) is pressed and the data was unsuccessfully stored to NVM due to a failure or corruption in the NVM, the FAILED WEIGHT CONFIGURATION CHANGE screen is displayed.
    F Failed Weight Configuration Change (Screen 10)
    Verify no EEC NVM faults are present and all Menu Mode conditions are satisfied. Reattempt weight configuration change.
Subtask 73-29-00-710-085-A
D. Coefficient Calculation and Selection
   (1) The engine balance coefficient selection allows the operator to select which coefficients are to be used by the advanced trim (1-plane) balance calculation algorithm. The operator may select generic coefficients, specific coefficients, or calculate new specific coefficients.
  • The generic coefficients are factory settings which apply to most engines.
  • The specific coefficients are unique to the engine based on previous engine run experience and may provide a more accurate engine balance.
  • If the operator selects to calculate new specific coefficients, the two most recent flight histories or ground runs which meet criteria are used to calculate new specific coefficients. The two flight histories or ground runs must have vibration data in at least one of the same speed bins and the difference in the same speed bin must be at least 1 Mil peak to peak in difference between selected legs fan weight configuration must be greater than 500 gm-cm for calculation of the coefficients.
5. Close-up
Subtask 73-29-00-710-097-A
A. Test(s)
   (1) Do the vibration check (Ref. AMM TASK 71-00-00-710-813).
Subtask 73-29-00-862-068-A
B. De-energize the aircraft electrical circuits
(Ref. AMM TASK 24-41-00-862-002).
Subtask 73-29-00-860-095-A
C. Put the aircraft back to its initial configuration.
   (1) Make sure that the work area is clean and clear of tools and other items.
[Rev.10 from 2021] 2026.04.01 12:57:52 UTC
"Aviabrain" 2025