Visual Inspection of the Fan Blade Platform [CFML]

TASK 72-21-42-210-801-A
Visual Inspection of the Fan Blade Platform

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: 210
ZONE: 400

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

REFERENCE	QTY	DESIGNATION
No specific	1	MAT - PROTECTIVE
No specific	AR	WARNING NOTICE(S)

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
210	CKPT,FWD COMPT BHD TO FLT COMPT BULKHEAD
400	POWER PLANT, NACELLES AND PYLONS

C. Referenced Information

REFERENCE	DESIGNATION
Fan Blade Platform

3. Job Set-up
Subtask 72-21-42-941-052-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
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).
(3) Install the MAT - PROTECTIVE in lower half of the inlet cowl.

4. Procedure
Subtask 72-21-42-210-050-A

A. Do the inspection of the fan blade platform:

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Examine the fan blade platform topskin bonded surface for:
(a) Cracks, tears and broken fibers	Not permitted. The over serviceable limits extension for cracks, tears and broken fibers is 10 cycles with these conditions: The cracks, tears and broken fibers have a maximum depth of 0.02 in. (0.51 mm). The cracks, tears and broken fibers have a maximum length of 1.0 in. (25.40 mm). All loose material is removed.
(b) Delamination	Not permitted.
(c) Damaged edges (crushed fiber or laminate) along the perimeter of the platform	Permitted up to a maximum depth of 0.02 in. (0.51 mm).	Examine the adjacent fan blades for damage.
(d) Erosion in the black film (polyurethane) surface coating	Permitted if the carbon ply beneath the polyurethane is not eroded.
	The over serviceable limits extension for erosion of the polyurethane surface coating into the carbon ply is 50 cycles.
(e) Scratches, nicks and chips in the black film (polyurethane) surface coating	Permitted if the carbon ply beneath the polyurethane cannot be seen.
	The over serviceable limits extension for scratches and nicks in the polyurethane surface coating that show the carbon ply beneath the polyurethane is 50 cycles.
(f) Resin crazing cracks at the Leading Edge (LE) and Trailing Edge (TE) radii	Permitted if there are no carbon fibers seen below the resin.	NOTE: The resin at the LE and TE radii will only be seen if the polyurethane surface coating is missing in these areas.
	The over serviceable limits extension for resin crazing cracks at the LE and TE radii where you can see the carbon fiber plies below the resin is 50 cycles.	NOTE: Fibers that can be seen are no longer sealed by the resin.
	No resin cracking going into carbon fiber plies.
(g) Chipped resin at the LE and TE radii	Permitted if there are no carbon fibers seen below the resin.
	The over serviceable limits extension for chipped resin at the LE and TE radii where you can see the composite carbon fiber plies below the resin is 10 cycles.
(h) Erosion and missing seal material	Missing seal lip allowed to a maximum of 2 in. (50.80 mm) along each side.	NOTE: Top of gray seal lip should be visible between fan platform edge and fan blade wear strip interface along both sides of platform.
	The over serviceable limits extension for missing seal lip is 50 cycles.

5. Close-up
Subtask 72-21-42-942-051-A

A. Put the aircraft back to its initial configuration.
(1) Remove the MAT - PROTECTIVE in lower half of the inlet 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 13:03:35 UTC