Fan Trim Balance with the EVMU (one Shot Method) [CFMB]

TASK 77-32-34-750-001-A
Fan Trim Balance with the EVMU (one Shot Method)

1. Reason for the Job
This task is applicable only for CFM56-5B post airbus SB 77-1006 (P/N 241-246-022-004).
You can use this procedure for consecutive fan trim balances if necessary. If consecutive fan trim balances with this method do not give significant results, do a fan trim balance with the vectorial method.

NOTE: To do this procedure, flight or ground vibration data must be available (Ref. AMM TASK 77-32-34-860-042) or (Ref. AMM TASK 77-32-34-860-043).

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 75 and 65 lbf.in (0.85 and 0.73 m.daN )

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CP5062)	MoS_2 dry film lubricant

C. 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 31-32-00-860-012-A	Procedure to Get Access to the SYSTEM REPORT/TEST/ENG Page
TASK 77-32-34-860-042-A	Acquire Unbalance Data During the Flight and Read Unbalance Data
TASK 77-32-34-860-043-A	Unbalance Acquisition on the Ground
Trim Balance - One Shot Method

3. Job Set-up
Subtask 77-32-34-861-069-A ** ON A/C NOT FOR ALL

A. Energize the aircraft electrical circuits (Ref. AMM TASK 24-41-00-861-002).

Subtask 77-32-34-865-078-A ** ON A/C NOT FOR ALL

B. Make sure that this(these) circuit breaker(s) is(are) closed:

PANEL	DESIGNATION	FIN	LOCATION
** ON A/C NOT FOR ALL
121VU	ENGINE/ENG1 AND 2/EVMU	1EV	R44

Subtask 77-32-34-941-052-A ** ON A/C NOT FOR ALL

C. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 77-32-34-860-065-A ** ON A/C NOT FOR ALL

D. Aircraft System Configuration
(1) On the spinner rear cone, record the identification (P0X) and the position of all the 36 balance screws.

NOTE: The balance screws are identified by a number (P0X) engraved on the screw head.

NOTE: The numbering of the balance screws can be different due to different bolt supplier, from P01 to P07 or from P08 to P14, however, they are identical in terms of balance: P01=P08, P02=P09, P03=P10, P04=P11, P05=P12, P06=P13 and P07=P14.

NOTE: A spherical mark is machined on the spinner rear cone to show the fan blade No.1 location. The fan blade No.1 is to the left of the mark, forward looking aft (the blades are counted counterclockwise).

Subtask 77-32-34-869-098-A ** ON A/C NOT FOR ALL

E. Aircraft Maintenance Configuration
(1) To do this procedure, flight or ground vibration data must be available (Ref. AMM TASK 77-32-34-860-042) or (Ref. AMM TASK 77-32-34-860-043).
(2) On the MCDU 1(2), get the SYSTEM REPORT/TEST ENG page (Ref. AMM TASK 31-32-00-860-012).
(3) Push the key adjacent to the EVMU indication: the first EVMU page comes into view.
(4) Push the NEXT PAGE key.
(5) Push the key adjacent to the ENGINE UNBALANCE indication
(6) The EVMU ENGINE UNBALANCE menu comes into view.

4. Procedure
Subtask 77-32-34-750-050-A ** ON A/C NOT FOR ALL

A. Do the fan trim balance.

ACTION	RESULT
1.Push the line key adjacent to the ENG1(2) TRIM indication.	The EVMU ENG1(2) TRIM BALANCE menu comes into view.
2.Push the line key adjacent to the ONE SHOT TRIM BALANCE CFM56-5B indication.	The EVMU ENG1(2) CURRENT VIB INPUT menu comes into view.
3.Push the line key related to the data that you use to do the trim balance: FLIGHT DATA or GROUND DATA or MANUAL INPUT.	The vibration data comes into view.
4.Collect the vibration data on the result sheet or by a print of the MCDU screens. These data are necessary if you must do a trim balance with the vectorial method.
5.Push the line key adjacent to the CONT indication.	The INFLUENCE COEFF SELECT menu comes into view.
6.Push the line key adjacent to the GENERIC COEFF CFM56-5B indication. NOTE: You can use a specific coefficient to trim balance the engine. In this case you must type the N1/SENS/DEG data for the bearing 1 and TRF sensors in the ENG1(2) SPECIFIC COEFF menu.	The ENG1(2) INSTALLED CURRENT SCREWS menu comes into view. Compare the data shown on the MCDU with the data collected in step D. for all the 36 holes and if necessary type on the keyboard the screw identification (P0X) and press the line key adjacent to the current screw position.

7.Collect the hole/screw configuration on the result sheet or by a print of the MCDU screens. These data are necessary if you must do a trim balance with the vectorial method.
8.Push the line key adjacent to the CONT indication to memorize the screw configuration.	The ENG1(2) SCREWS TO CHANGE menu comes into view. Do a print of this page and if there is more than one page, on the MCDU keyboard, push the NEXT PAGE pushbutton and do a print of each page.
9.If you want to keep this new configuration push the line key adjacent to the UPDATE indication.	NOTE: If the line key adjacent to the UPDATE indication is pushed, the new values replace the values in the ENG1(2) INSTALLED CURRENT SCREWS menu.
10.On the MCDU, push the line select key adjacent to the RETURN indication until the CFDS menu page comes into view.

(1) On the spinner rear cone change the balance screws as indicated.
(a) Lightly coat the balance screws with MoS_2 dry film lubricant (Material No.CP5062) .
(b) TORQUE the balance screws to between 75 and 65 lbf.in (0.85 and 0.73 m.daN )

5. Close-up
Subtask 77-32-34-942-054-A ** ON A/C NOT FOR ALL

A. Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.02 06:37:44 UTC