Detailed Inspection of Inner and Outer Finger Seals [CFML]

TASK 78-12-41-220-801-A
Detailed Inspection of Inner and Outer Finger Seals

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
Refer to the MPD TASK: 781000-L1
DETAILED INSPECTION OF INNER AND OUTER FINGER SEALS.

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

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

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
400	POWER PLANT, NACELLES AND PYLONS
FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL, 438AR, 451AL, 452AR
FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL, 448AR, 461AL, 462AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-803-A	Opening of the Fan Cowl Doors
TASK 71-13-00-410-803-A	Closing of the Fan Cowl Doors
TASK 78-12-41-000-801-A	Removal of the Finger Seals
TASK 78-12-41-400-801-A	Installation of the Finger Seals
TASK 78-12-41-960-801-A	Discard of Exhaust Outer and Inner Finger Seals
TASK 78-30-00-040-807-A	Deactivation of the Thrust Reverser System for Nacelle Maintenance (ICU)
TASK 78-30-00-440-807-A	Reactivation of the Thrust Reverser System after Nacelle Maintenance (ICU)
TASK 78-36-00-010-806-A	Opening of the Thrust Reverser Cowl Doors
TASK 78-36-00-410-806-A	Closing of the Thrust Reverser Cowl Doors
Illustration of Detailed Inspection of the Inner and Outer Finger Seals

3. Job Set-up
Subtask 78-12-41-941-052-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 a 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).

Subtask 78-12-41-010-056-A

B. Get Access
(1) Open the fan cowl doors (Ref. AMM TASK 71-13-00-010-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR

Subtask 78-12-41-040-052-A

C. Deactivation of the Thrust Reverser System for Nacelle Maintenance

WARNING: YOU MUST DEACTIVATE THE THRUST REVERSER BEFORE YOU DO WORK ON OR AROUND IT. IF YOU DO NOT, THE THRUST REVERSER CAN OPERATE ACCIDENTALLY AND CAUSE AN INJURY AND/OR DAMAGE.

(1) Do the deactivation of the thrust reverser system for nacelle maintenance (Ref. AMM TASK 78-30-00-040-807).

Subtask 78-12-41-010-057-A

D. Get Access
(1) Open the thrust reverser cowl-doors (Ref. AMM TASK 78-36-00-010-806):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
451AL 452AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
461AL 462AR
(2) Put an ACCESS PLATFORM 1M (3 FT)-ADJUSTABLE in position.
(3) Get access to the thrust reverser 12 o'clock area.

Subtask 78-12-41-010-061-A

E. Removal of the Finger Seals.
(1) Remove the Finger Seals (Ref. AMM TASK 78-12-41-000-801).

4. Procedure
Subtask 78-12-41-220-050-A

A. Detail Inspection of the Coating on the Outer Finger Seals

Illustration of Detailed Inspection of the Inner and Outer Finger Seals

NOTE: You can use a LIGHT SOURCE - INSPECTION and a MIRROR - INSPECTION to perform this inspection.

(1) Do a detailed inspection of the exhaust nozzle finger seals (1) for damage on the tungsten carbide coating area:
(a) Make sure that the tungsten carbide coating is not missing over its entire thickness, even locally.

NOTE: It is normal to observe some marks due to contact between finger seal and landing. Worn tungsten carbide coating generates depth. If excessive wear depth can be detected by human finger, replace exhaust nozzle finger seal (1) (Ref. AMM TASK 78-12-41-960-801).

NOTE:

Illustration of Detailed Inspection of the Inner and Outer Finger Seals

Subtask 78-12-41-220-051-A

B. Detail Inspection of the Inner and Outer Finger Seals

Illustration of Detailed Inspection of the Inner and Outer Finger Seals

NOTE: You can use a LIGHT SOURCE - HIGHPOWER and a MIRROR - INSPECTION to perform this inspection.

(1) Do the detailed inspection of the finger seals (1) for the following damages:

Finger missing
Finger with holes or material loss
Finger seals not in contact with the landing or other layer of the finger seal
Missing screws.

(2) If you find damage, replace the exhaust nozzle finger seal (1) (Ref. AMM TASK 78-12-41-960-801).
(3) If you find a screw missing, install a new screw (Ref. AMM TASK 78-12-41-400-801).

5. Close-up
Subtask 78-12-41-410-058-A

A. Installation of the Finger Seals.
(1) Install the Finger Seals (Ref. AMM TASK 78-12-41-400-801).

Subtask 78-12-41-410-056-A

B. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Remove the access platform(s).
(3) Close the thrust reverser cowl-doors (Ref. AMM TASK 78-36-00-410-806):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
451AL 452AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
461AL 462AR

Subtask 78-12-41-440-053-A

C. Do the reactivation of the thrust reverser system after nacelle maintenance (Ref. AMM TASK 78-30-00-440-807).

Subtask 78-12-41-410-057-A

D. Close Access
(1) Close the fan cowl doors (Ref. AMM TASK 71-13-00-410-803):
(a) FOR [4020KM1] (POWER PLANT-DEMOUNTABLE, ENGINE 1)
437AL 438AR
(b) FOR [4020KM2] (POWER PLANT-DEMOUNTABLE, ENGINE 2)
447AL 448AR
(2) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 03:34:35 UTC