Borescope Inspection of the Stage 2 High Pressure Turbine (HPT) Shrouds [CFML]

TASK 72-00-00-290-821-A
Borescope Inspection of the Stage 2 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.

1. Reason for the Job
This procedure uses a flexible borescope to do a 360-degree inspection of the stage 2 High Pressure Turbine (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 DIA 5.0 MM (7/32 IN) - FLEXIBLE
No specific	1	BORESCOPE SET
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 97.2 and 82.8 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
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 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 2 High Pressure Turbine (HPT) Shrouds

3. Job Set-up
Subtask 72-00-00-941-248-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 72-00-00-010-335-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 72-00-00-040-162-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 72-00-00-010-336-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 72-00-00-010-337-A

A. Remove the port S borescope plug from the High Pressure Turbine (HPT) case (Ref. AMM TASK 72-00-00-290-812).

Subtask 72-00-00-290-143-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 2 HPT shrouds as follows:

Component	Quantity of Segments
Stage 2 HPT Shroud Segments	36

NOTE: A BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE is necessary for this inspection if you use a guide tube. A BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE with a minimum length of 90 in. (2.29 m) is necessary to do the 360-degree borescope inspection of the Stage 2 HPT shrouds.

NOTE: It is optional to use a BORESCOPE SET (dia 0.24 in. (6.10 mm)) without the 956A1603G01 GUIDE TUBES, BORESCOPE.

(1) If you will use a guide tube, put the 956A1603G01 GUIDE TUBES, BORESCOPE into HPT case port S.
(2) Move the end of the 956A1603G01 GUIDE TUBES, BORESCOPE into the hole in the stage 2 HPT nozzle and into the flow path.
(3) Put the BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE into the 956A1603G01 GUIDE TUBES, BORESCOPE and extend it into the stage 2 HPT flow path.
(4) Continue to move the BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE in the direction set by the stage 2 HPT nozzle vanes.
(5) Move the BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE across the top of the engine, 360 degrees around the engine until you can see the BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE.
(6) Inspection limits for the stage 2 HPT shrouds:

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Stage 2 HPT shroud for:
A.Blade rub	Any amount is permitted.
B.Cracks	Not permitted.
C.Surface corrosion/ oxidation	Any amount is permitted, as long as no burn through is present on flow path surface of the shroud.
D.A hole through the shroud flow path surface	Not permitted.
E.Missing material from split line	Any amount allowed in the split line region up to 0.075 in. (1.90 mm) from the end face.
	A 500 cycles interval is permitted in these conditions:
	Any number, if more than 0.075 in. (1.90 mm) if missing material from split line.	The over serviceable limit extensions are at decreased interval, inspection must be done again after max 500 engine cycles.
	More than 0.110 in. (2.79 mm) of missing material from split line not permitted.
F.Missing flow path spline seals	Up to eight.	No action necessary.
	More than eight.	Inspection after max 500 engine cycles.

(7) Examine all 36 stage 2 HPT shrouds as you pull the BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE back around the full 360 degree path.
(8) Do an inspection of the mid-chord of the stage 2 HPT stator shrouds (area of the stage 2 HPT stator shrouds between the blades) and the leading edge of the stage 2 HPT stator shrouds.
(9) Extend the tip of the BORESCOPE DIA 5.0 MM (7/32 IN) - FLEXIBLE in the aft direction to see as much of the trailing edge as possible.

Subtask 72-00-00-410-294-A

C. Install the port S borescope plug into the HPT case as follows:
(1) If used, remove the 956A1603G01 GUIDE TUBES, BORESCOPE from port S.
(2) 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 are no clicking sounds when you turn the antirotation feature in the clockwise or counterclockwise direction.
(3) Apply graphite grease (Material No.CP2101) or CP2619Never Seez-Pure Nickel, Special to the threads of the port S borescope plug.
(4) Install the port S borescope plug into the HPT case.
(5) TORQUE the port S borescope plug to between 97.2 and 82.8 lbf.in (1.10 and 0.94 m.daN )

5. Close-up
Subtask 72-00-00-410-292-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 72-00-00-440-154-A

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

Subtask 72-00-00-410-293-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