Borescope Inspection of the Stage 1 High Pressure Turbine (HPT) Shrouds [CFML]

TASK 72-00-00-290-820-A
Borescope Inspection of the Stage 1 High Pressure Turbine (HPT) Shrouds

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.

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

ZONE: 210
ZONE: 400

1. Reason for the Job
This procedure uses a flexible borescope to do a 360-degree inspection of the stage 1 HPT shrouds.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 1M(3 FT)
No specific	1	BORESCOPE - FLEXIBLE
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 97 and 83 lbf.in (1.10 and 0.94 m.daN )
956A1603G01	2	GUIDE TUBES, BORESCOPE

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CP2101)	graphite grease
(Material No.CP2619)	Never Seez-Pure Nickel, Special

C. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
210	CKPT,FWD COMPT BHD TO FLT COMPT BULKHEAD
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

D. 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 72-00-00-290-812-A	Engine Borescope Examination Preparation
TASK 72-00-00-290-815-A	Borescope Inspection of the Stage 2 High Pressure Turbine (HPT) Nozzle Guide Vanes (NGVs)
TASK 78-30-00-040-809-A	Deactivation of the Thrust Reverser System for Ground Maintenance
TASK 78-30-00-440-809-A	Reactivation of the Thrust Reverser System after Ground Maintenance
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
Borescope Inspection of the Stage-1 HPT Shrouds

3. Job Set-up
Subtask 72-00-00-941-247-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 72-00-00-010-332-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
(2) Put an ACCESS PLATFORM 1M(3 FT) in position.

Subtask 72-00-00-040-161-A

C. Deactivation of the Thrust Reverser System for 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 ground maintenance (Ref. AMM TASK 78-30-00-040-809).

Subtask 72-00-00-010-333-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

4. Procedure
Subtask 72-00-00-010-334-A

A. Removal of the port R and S borescope plug from the HPT case
(1) Remove the port R borescope plug from the HPT case. This port gives access for the inspection of the Leading Edge (LE) of the stage 1 HPT shroud (Ref. AMM TASK 72-00-00-290-812).
(2) Remove the port S borescope plug from the HPT case. This port gives access for the inspection of the Trailing Edge (TE) of the stage 1 HPT shroud (Ref. AMM TASK 72-00-00-290-812).
(3) Put an identification tag on each borescope plug.

Subtask 72-00-00-290-142-A

CAUTION: BE CAREFUL WHEN YOU MOVE THE FLEXIBLE BORESCOPE INTO THE ENGINE. YOU CAN EASILY DO DAMAGE TO THE BORESCOPE EQUIPMENT IF YOU ARE NOT CAREFUL.

CAUTION: MAKE SURE THE TEMPERATURE OF THE ENGINE AND OF THE AREAS ADJACENT TO THE BORESCOPE INSPECTION PORTS IS LESS THAN 150 °F (65.6 °C). DO NOT DO A BORESCOPE INSPECTION IF THE ADJACENT AREAS ARE TOO HOT TO TOUCH. DO THE BORESCOPE INSPECTION WHEN THE ENGINE TEMPERATURE IS LESS THAN 150 F(65.6 C). THIS WILL PREVENT DAMAGE TO THE BORESCOPE EQUIPMENT.

CAUTION: WHEN YOU DO THE INSPECTION, MAKE SURE THAT YOU SEE THE POINT WHERE THE FLEXSCOPE IS BETWEEN THE TWO VANES OF THE STAGE 1(2) HPT NOZZLE. THIS WILL LET YOU DO A FULL 360-DEGREE INSPECTION.

B. Do a 360-degree borescope inspection of the stage-1 HPT shrouds as follows:

Component	Quantity of Segments
Stage-1 HPT shroud segments	18

NOTE: The BORESCOPE - FLEXIBLE with a minimum length of 90 in. (2.29 m) is necessary to do the 360-degree borescope inspection of the HPT stage-1 shrouds. If you use the 956A1603G01 GUIDE TUBES, BORESCOPE, the BORESCOPE - FLEXIBLE (with a diameter of 0.15 in. (4 mm)) is necessary to do this inspection.

NOTE: It is optional to use the BORESCOPE - FLEXIBLE (with a diameter of 0.24 in. (6 mm)) without the 956A1603G01 GUIDE TUBES, BORESCOPE.

(1) If you use the guide tube, put the 956A1603G01 GUIDE TUBES, BORESCOPE into HPT case port R.
(2) Move the end of the 956A1603G01 GUIDE TUBES, BORESCOPE into the hole in the stage-1 HPT nozzle and into the flowpath.
(3) Put the BORESCOPE - FLEXIBLE into the 956A1603G01 GUIDE TUBES, BORESCOPE and extend it into the stage-1 HPT flowpath.
(4) Continue to move the BORESCOPE - FLEXIBLE in the direction set by the stage-1 HPT nozzle-vanes.
(5) Move the BORESCOPE - FLEXIBLE across the top of the engine 360 degrees around the engine until you can see the BORESCOPE - FLEXIBLE.
(6) Inspection limits for the stage-1 HPT shrouds:

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.The stage-1 HPT shroud for:		NOTE: The inspection instructions and limits are applicable to the LE and the TE of the stage-1 HPT shrouds.
A.Blade rubs	There is no limit to the amount of permitted blade rubs.
B.Cracks in the shroud base material	Any amount of 0.6 in. (15.24 mm) in length maximum.
C.Cracks in the flow path coating	In the area 0.5 in. (12.70 mm) from the TE: Cracks in the coating of 1.5 in. (38.10 mm) in length maximum are permitted. In all other areas, any amount of 0.6 in. (15.24 mm) in length maximum.
D.Missing flow path coating	In the areas that are 0.10 in. (2.54 mm) from the LE and the TE, any amount of missing coating and exposed base material is permitted. For the remaining areas that are more than 0.100 in. (2.54 mm) from the LE and the TE, a maximum sum of 0.250 in.2 (161.29 mm2) of missing coating on each shroud is permitted. Exposed base material, where the coating is completely missing, is not permitted in these areas.	For missing coating, over-serviceable limit extension, refer to H. If the shroud segment is missing complete circumferential EBC in or less than 0.100 in. (2.54 mm) of the TE, do an inspection of the LEs of the three adjacent stage 2 nozzle segments (Ref. AMM TASK 72-00-00-290-815).
E.Chipping of the shroud segment base material along the LE and the TE	Two chips on each shroud segment are permitted if the maximum length is less than 0.050 in. (1.27 mm) from the edge.
F.Chipping of the shroud segment base material along the circumferential split line	A maximum axial length of 1.0 in. (25.4 mm) is permitted on up to 10 shroud segments, each end.
G.Missing spline seals	Up to 18 missing or partially missing discourager spline seals and up to 10 missing or partially missing primary spline seal per engine is permissible.
H.The over-serviceable limit extension for missing coating on the shroud segment flowpath surface	PRE SB LEAP-1A-72-00-0119-01A-930A-D Check the engine data plate for thrust rating 1A23, 1A24, 1A24E1, 1A26 and 1A26E1: A 500-cycle inspection interval is permitted with this condition: Any amount of missing coating on the shroud segment, provided there is no oxidation on the adjacent stage-2 nozzle outer platform LE. A 200-cycle inspection interval is permitted with this condition: Any amount of missing coating on the shroud segment, oxidation on the adjacent stage-2 nozzle outer platform LE is permitted. Check the engine data plate for thrust rating 1A30, 1A32, 1A33, 1A33B2 and 1A35A: A 200-cycle inspection interval is permitted with this condition: Any amount of missing coating on the shroud segment, provided there is no oxidation on the adjacent stage-2 nozzle outer platform LE. A 100-cycle inspection interval is permitted with this condition: Any amount of missing coating on the shroud segment, oxidation on the adjacent stage-2 nozzle outer platform LE is permitted. END PRE SB LEAP-1A-72- 00-0119-01A-930A-D	This over-serviceable limit extension is for a reduced interval. Do the inspection again. For the spline seals - missing material at the circumferential ends, refer to K.
J.The over-serviceable limit extension for missing coating on the shroud segment flowpath surface	POST SB LEAP-1A-72-00- 0119-01A-930A-D A 1600-cycle inspection interval is permitted with these conditions: In the areas between 0.10 in. (2.5400 mm) and 0.30 in. (7.6200 mm) from the TE, any amount of missing coating is permitted if the base material is not exposed. In the areas between 0.66 in. (16.8 mm) from the TE and 0.40 in. (10.2 mm) from the circumferential split line, any amount of missing coating and exposed based material is permitted. A 600-cycle inspection interval is permitted with this condition: Any amount of missing coating on the shroud segment. END POST SB LEAP-1A- 72-00-0119-01A-930A-D POST SB LEAP-1A-72-00- 0213-01A-930A-D A 1600-cycle inspection interval is permitted with this condition: Any amount of missing coating on the shroud segment. END POST SB LEAP-1A-72-00-0213-01A- 930A-D Remove the engine in ten cycles or less with this condition: If a hole through the shroud segment is found.	This over-serviceable limit extension is for a reduced interval. Do the inspection again. For the spline seals - missing material at the circumferential ends, refer to K.
K.The over-serviceable limit extension for chipping of the shroud segment base material along the LE and the TE	A 800-cycle inspection interval is permitted with this condition: Chipping of the shroud base material up to 0.25 in. (6.3 mm) from the LE and up to 0.15 in. (3.8 mm) from the TE. A 100-cycle inspection interval is permitted with this condition: Chipping of the shroud base material up to 0.35 in. (8.9 mm) from the LE and to 0.25 in. (6.3 mm) from the TE.
L.The over-serviceable limit extension for chipping of the shroud segment base material along the circumferential split line	A 200-cycle inspection interval is permitted for the maximum limit that follows: A maximum axial length of 1.00 in. (25.40 mm) is permitted on each shroud segment.

(7) Examine all 18 stage-1 HPT shrouds as you pull the BORESCOPE - FLEXIBLE back around the full 360-degree path.
(8) Do an inspection of the mid-chord of the stage-1 HPT stator shrouds (the area of the stage-1 HPT stator-shrouds between the blades) and the LE of the stage-1 HPT stator-shrouds.
(9) If you use the guide tube, put the 956A1603G01 GUIDE TUBES, BORESCOPE into HPT case port S.
(10) Move the end of the 956A1603G01 GUIDE TUBES, BORESCOPE into the hole in the stage-2 HPT nozzle and into the flowpath.
(11) Put the BORESCOPE - FLEXIBLE into the 956A1603G01 GUIDE TUBES, BORESCOPE and extend it into the stage-2 HPT flowpath.
(12) Continue to move the BORESCOPE - FLEXIBLE in the direction set by the stage-2 HPT nozzle-vanes.
(13) Move the BORESCOPE - FLEXIBLE across the top of the engine, 360 degrees around the engine until you can see the BORESCOPE - FLEXIBLE.
(14) Examine all 18 stage-1 HPT shrouds as you pull the BORESCOPE - FLEXIBLE back around the full 360-degree path.
(15) Do an inspection of the mid-chord of the stage-1 HPT stator-shrouds (the area of the stage-1 HPT stator-shrouds between the blades) and the TE of the stage-1 HPT stator-shrouds.

Subtask 72-00-00-410-289-A

C. Install the port R and port S borescope plugs into the HPT case as follows:
(1) If used, remove the 956A1603G01 GUIDE TUBES, BORESCOPE from port R and port S.
(2) Remove the identification tag from the borescope plugs R and S before the installation of each plug.
(3) Do a visual inspection of the borescope plugs and the borescope ports (Ref. AMM TASK 72-00-00-290-812).
(4) Verify borescope plug antirotation feature quality:
(a) Holding the borescope plug in one hand and holding the area near the tab, turn the antirotation feature one full revolution.
(b) Replace the borescope plug if there is no clicking sound when you turn the antirotation feature in the clockwise or counterclockwise direction.
(5) Apply graphite grease (Material No.CP2101) or CP2619Never Seez-Pure Nickel, Special to the threads of the port R and port S borescope plugs.
(6) Install the port R and port S borescope plugs into the HPT case.
(7) TORQUE the port R and port S borescope plugs to between 97 and 83 lbf.in (1.10 and 0.94 m.daN )

5. Close-up
Subtask 72-00-00-410-290-A

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) 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 72-00-00-440-153-A

B. Do the reactivation of the thrust reverser system after ground maintenance (Ref. AMM TASK 78-30-00-440-809).

Subtask 72-00-00-410-291-A

C. 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 access platform(s).
(3) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 13:03:40 UTC