Replacement of the Fan Blades [CFML]

TASK 72-21-20-960-801-A
Replacement of the Fan Blades

WARNING: BE CAREFUL WHEN YOU DO WORK ON THE ENGINE PARTS AFTER THE ENGINE SHUTDOWN. USE APPLICABLE THERMAL GLOVES. THE ENGINE PARTS CAN STAY HOT FOR ONE HOUR AFTER SHUTDOWN AND CAN BURN YOU.

ZONE: 400

1. Reason for the Job
The replacement of the fan blades can be done individually or in pairs depending on the conditions described in the following paragraph.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	MAT - RUBBER
No specific	AR	WARNING NOTICE(S)
956A7671G02	1	FAN BLADE MAPPING SOFTWARE

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
400	POWER PLANT, NACELLES AND PYLONS

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-00-00-710-813-A	Vibration Check
TASK 72-21-20-000-801-A	Removal of the Fan Blades
TASK 72-21-20-400-801-A	Installation of the Fan Blades
TASK 72-21-43-000-801-A	Removal of the Platform Front Shroud Balance Weight
TASK 72-21-43-400-801-A	Installation of the Platform Front Shroud Balance Weight
TASK 73-29-00-710-805-A	Conduct a Ground Run (Menu Mode)
TASK 73-29-00-740-808-A	Engine Trim Balancing via Menu Mode
Fan Blades

3. Job Set-up
Subtask 72-21-20-941-053-A

A. Safety Precautions
(1) On the center pedestal, on ENG panel 115VU:
(a) Make sure that the ENG/MODE selector switch is in the NORM position.
(b) Make sure that the ENG/MASTER 1(2) control switch was in the OFF position not less than five minutes before you do this procedure.
(c) Put WARNING NOTICE(S) in position to tell persons not to operate:

The ENG/MODE selector switch, and
The ENG/MASTER 1(2) control switch.

(2) On the ENG section of maintenance panel 50VU:
(a) Make sure that the ON legend of the FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) in position to tell persons not to energize FADEC 1(2).

4. Procedure
Subtask 72-21-20-020-052-A

A. Removal of the Fan Blades in Pairs

NOTE: Three moment weights named as axial, tangential and radial are engraved on the fan blade root. These moment weights are used when a fan blade mapping is necessary. For a fan blade replacement of less than or equal to three pairs, only the radial moment weight is to be considered.

NOTE: Spare blades are delivered in pairs so that the difference between the radial moment weights of the two fan blades is not more than 0.52 lb in. (600 g cm) as it is for all the opposite blades constituting the set.

NOTE: If you replace more than three pairs of the fan blades, you must do a fan blade mapping and a vibration check (Ref. AMM TASK 71-00-00-710-813).

NOTE: There are three configurations of the balancing device. They are as follows:

Hole-free
Hole with the bolt and the nut
Hole with the bolt, nut and weight.

(1) Two conditions can exist as given below:
(a) Up to three pairs are changed.
(b) More than three pairs are changed:
1 If you replace more than three pairs of the fan blades, you must do a fan blade mapping and a vibration check (Ref. AMM TASK 71-00-00-710-813).
2 If the vibration check is not satisfactory, do a vibration survey (ground run) (Ref. AMM TASK 73-29-00-710-805) and a trim balance (Ref. AMM TASK 73-29-00-740-808).
(2) Put the MAT - RUBBER at the air intake cowl.
(3) Remove the fan blades from the opposite pairs (Ref. AMM TASK 72-21-20-000-801).
(4) Record the moment weight orientation and the position of the replaced fan blade pairs (position of the heaviest and the lightest blades for each replaced pair ):
(a) Replace by the new pair with the same orientation (heaviest and lightest).
(5) Do a check of the quantity of the replaced fan blades :
(a) If the quantity of the pairs is less than or equal to three and the pair radial moment weight is not more than 0.52 lb in. (600 g cm):
1 Do not remove the weight balance from the platform front shroud.
2 Check the resultant moment weight of the new pairs replaced per the LEAP software for a blade mapping with the 956A7671G02 FAN BLADE MAPPING SOFTWARE
a If the resultant moment weight of all the new pairs is not more than 0.61 lb in. (700 g cm) versus the removed blade pairs (different moment weight), then reinstall the fan blades (Ref. AMM TASK 72-21-20-000-801) and (Ref. AMM TASK 72-21-20-400-801).
Return the engine to service.
b If the resultant moment weight of all the new pairs is more than 0.61 lb in. (700 g cm) versus all the removed blade pairs, it is the customer's convenience to do a vibration check (Ref. AMM TASK 71-00-00-710-813) depending on the information below:

Add up around one mils per 0.61 lb in. (700 g cm) of the resultant moment weight difference with the removed fan blade pairs. Depending on the previous vibration level recorded by the Full Authority Digital Engine Control (FADEC), this gives you an indication to do or not to do a vibration check.
As an indication, if the vibration level was 2.5 mils Drift Angle (DA) before the fan blade change and if the resultant moment weight is equal to 1.22 lb in. (1400 g cm), you must add up two mils DA and the vibration level will be around 4.5 mils DA.
If the resultant moment weight is 1.82 lb in. (2100 g cm), the vibration level will be around 5.5 mils DA.

NOTE: Six mils DA is a six (Control Unit) CU cockpit advisory.

(b) If the quantity of the pairs is more than three, or the radial moment weight of a minimum of one pair is more than 0.52 lb in. (600 g cm):

Remove the bolt nuts and the moment weight from the platform front shroud.
Remove the fan blades, record the moment weight and the position of each fan blade.
Do a blade mapping with the 956A7671G02 FAN BLADE MAPPING SOFTWARE.
Reinstall the fan blades (Ref. AMM TASK 72-21-20-400-801).
Do a vibration check (Ref. AMM TASK 71-00-00-710-813).
If the vibration check is not satisfactory, do a vibration survey (ground run) (Ref. AMM TASK 73-29-00-710-805) and a trim balance (Ref. AMM TASK 73-29-00-740-808).

Subtask 72-21-20-960-050-A

B. Replacement of the Individual Fan Blades
(1) Do the steps that follow based on the three conditions that exist:
(a) If the number of the blades to be replaced is less than or equal to three and the radial moment weight of the blades to be replaced is less than or equal to 0.52 lb in. (600 g cm) versus the opposite remaining blades (remove the opposite blades to check their radial moment weight).
1 This configuration is equivalent to the procedure related to the fan blade removal in pairs. Refer to Para 4.A.
(b) If the number of the blades to be replaced is less than or equal to three and the moment radial weight of the blades to be replaced is more than or equal to 0.52 lb in. (600 g cm) versus the opposite remaining blades (remove the opposite blades to check their radial moment weight).
1 Do a static correction using the LEAP software:
a If the static correction solution is possible, position the bolts and the weights as referred to in tasks (Ref. AMM TASK 72-21-43-000-801) (Ref. AMM TASK 72-21-43-400-801) recommended by the software, do a vibration check (Ref. AMM TASK 71-00-00-710-813). If the vibration check is not satisfactory, do a vibration survey (ground run) (Ref. AMM TASK 73-29-00-710-805) and a trim balance (Ref. AMM TASK 73-29-00-740-808), if necessary. The vibration check is necessary because the static correction of one major module may increase a second vibration mode.
b If the static correction solution is not given by the software due to the static correction that is more than the maximum correction capacity, do a fan blade mapping.

NOTE: Several consecutive static corrections limit the correction possibility and the fan blades replaced in pairs must be done in priority to avoid the fan blade mapping procedure.

5. Close-up
Subtask 72-21-20-710-050-A

A. Test(s)
(1) Do the vibration check (Ref. AMM TASK 71-00-00-710-813).

Subtask 72-21-20-942-052-A

B. Put the aircraft back to its initial configuration.
(1) Remove the MAT - RUBBER at the air intake cowl.
(2) Make sure that the work area is clean and clear of tools and other items.
(3) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 02:51:39 UTC