Correction of the Static Imbalance [CFMB]

TASK 72-21-00-300-009-A
Correction of the Static Imbalance

FIN: 1000EM1 ** ON A/C NOT FOR ALL
FIN: 1000EM2 ** ON A/C NOT FOR ALL

1. Reason for the Job
Self explanatory
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE
No specific	AR	WARNING NOTICE(S)

B. Referenced Information

REFERENCE	DESIGNATION
TASK 71-00-00-710-009-B	Vibration Check
TASK 71-00-00-750-001-B	Fan Trim Balance - 1 Sensor 3 Speed
TASK 71-00-00-750-001-B-03	Fan Trim Balance - 1 Sensor 1 Speed
Various Balance Screw Arrangements for Given Moment Weights
Static Imbalance Correction
Balance Screws

3. Job Set-up
Subtask 72-21-00-941-074-A ** ON A/C NOT FOR ALL

A. 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).
(4) Put an ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position.

4. Procedure
Subtask 72-21-00-750-053-A ** ON A/C NOT FOR ALL

A. Example of static imbalance correction on a spinner still equipped with balance screws other than P07.

Static Imbalance Correction ** ON A/C NOT FOR ALL

Balance Screws ** ON A/C NOT FOR ALL

(1) Assume a balance weight Fc = 480 cm.g (189 in.g) orientated toward balance screw No. 24, is to be installed on the spinner which is still equipped with balance screws P02 in screw positions No. 18 and 19, and P05 in screw position No. 22.
(2) Both screws P02 have a total moment weight F1 of 327 cm.g (129 in.g) acting along an axis between both screws.
(3) Screw P05, installed in position No. 22, has a moment weight F2 of 375 cm.g (148 in.g) acting along an axis going through the screw location.
(4) Vectorial sum corresponding to the 3 balance screws has a resultant F3 of approximately 656 cm.g (258 in.g).
(5) Fc and F3 have a vectorial sum Ft of 1.072 cm.g (422 in.g) acting along an axis close to balance screw No. 22.
(6) Show that 1 centered screw P04 and 2 lateral screws P05 provide a total moment weight of 1048 cm.g (413 in.g).

Various Balance Screw Arrangements for Given Moment Weights ** ON A/C NOT FOR ALL

(7) One balance screw P04 must be installed in position 22 and 2 lateral screws P05 must be installed in positions 21 and 23, instead of screws previously installed.

NOTE: As vectorial sum Ft defined in paragraph A(5) is greater than 400 cm.g (157 in.g), static correction must be followed by a trim balance operation (Ref. AMM TASK 71-00-00-750-001).

NOTE: You can do a vibration check (Ref. AMM TASK 71-00-00-710-009) when you replace the fan blade(s) or when you install the same fan blade set again. The results of the survey will show if it is necessary to do a fan trim balance or if the installation is correct (Ref. AMM TASK 71-00-00-750-001).

5. Close-up
Subtask 72-21-00-869-069-A ** ON A/C NOT FOR ALL

A. Make sure that the work area is clean and clear of tools and other items.

Subtask 72-21-00-942-068-A ** ON A/C NOT FOR ALL

B. Close Access
(1) Remove the access platform(s).
(2) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 02:41:20 UTC