Borescope Inspection of the Stage 1 High Pressure Turbine (HPT) Nozzle Guide Vanes [CFML]

TASK 72-00-00-290-814-A
Borescope Inspection of the Stage 1 High Pressure Turbine (HPT) Nozzle Guide Vanes

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 1 HPT nozzle guide vane trailing edges.
NOTE: Stage 1 HPT nozzle guide vane leading edges are examined with a rigid borescope (Ref. TASK 72-40-00-290-80100 Borescope Inspection of the Combustion Section).
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
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
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 72-40-00-290-801-A	Borescope Inspection of Combustion Section and Fuel Nozzles
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
Stage 1 HPT Nozzle Guide Vane Borescope Inspection

3. Job Set-up
Subtask 72-00-00-941-222-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).

Subtask 72-00-00-010-302-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 72-00-00-040-149-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 maintenance (Ref. AMM TASK 78-30-00-040-809).

Subtask 72-00-00-010-303-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 72-00-00-010-304-A

A. Removal of the port R borescope plug from the HPT case.

NOTE: This port gives access for the inspection of the trailing edges of the stage 1 HPT nozzle guide vanes (Ref. AMM TASK 72-00-00-290-812).

Component	Quantity of Segments
Stage 1 HPT Nozzle Guide Vanes	18

Subtask 72-00-00-290-132-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.

B. Do a 360-degree borescope inspection of the stage 1 HPT nozzle guide vane trailing edges as follows:

Stage 1 HPT Nozzle Guide Vane Borescope Inspection

NOTE: A BORESCOPE - FLEXIBLE (5 mm or less) is necessary for this inspection if you use guide tubes. A flexscope with a minimum length of 90 in. (2.29 m) is necessary to do the 360-degree borescope inspection of the trailing edges of the stage 1 HPT nozzle guide vanes.

NOTE: It is optional to use a 6 mm flexscope without the guide tubes.

(1) If you use a 956A1603G01 GUIDE TUBES, BORESCOPE, put the guide tube into port R.
(2) Insert the BORESCOPE - FLEXIBLE into borescope port R and extend it into the flowpath between the stage 1 HPT nozzle trailing edge and the stage 1 HPT lead edge.
(3) Continue to move the flexscope in the direction set by the stage 1 HPT nozzle vanes.
(4) Move the flexscope across the top of the engine, 360 degrees around the engine until you can see the flexscope.

NOTE: It is very important that you can see the point where the flexscope is between the two vanes of the stage 1 HPT nozzle. This is necessary to be sure you do a full 360-degree inspection.

(5) Inspection limits for the inspection of the stage 1 HPT nozzle guide vane trailing edges:

NOTE: You can use a flexscope as an alternative to the rigid scope to examine the stage 1 HPT nozzle guide vane airfoil leading edges (Ref. AMM TASK 72-40-00-290-801).

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Trailing edge of vane airfoil for:
(a) Axial cracks starting from the slots adjacent to the trailing edge	There is no limit to the number permitted.
(b) Burns and cracks	There is no limit to the amount permitted if no material is missing and the burns are not fully through.	A maximum area of 0.875 in.2 (564.52 mm2) of missing material on each airfoil is permitted for a maximum of 25 cycles.
		A maximum area of 3.5 in.2 (2258.06 mm2) of missing material on the full nozzle assembly is permitted for a maximum of 25 cycles.
(c) Buckling or bowing	There is no limit to the amount permitted.
(d) Missing material (loss of metal)	The area of missing material must not be more than 0.525 in.2 (338.71 mm2) for each airfoil.
2.All areas of airfoil for:
(a) Craze cracking	There is no limit to the number permitted.	NOTE: Craze cracking looks like many surface cracks that have no visual width or depth.
(b) Nicks, scores, scratches and dents	There is no limit to the number permitted.
(c) Metal splatter	There is no limit to the amount permitted.
(d) Missing thermal barrier coating	There is no limit to the quantity of the thermal barrier coating that can be missing.
3.Inner and outer platform for:
(a) Cracks in parent metal	There is no limit to the number permitted if no material is missing.	A maximum area of 0.07 in.2 (45.16 mm2) of missing material on each airfoil because of cracks or burnthrough is permitted for a maximum of 25 cycles.
		A maximum area of 0.35 in.2 (225.81 mm2) of missing material on the entire nozzle assembly because of cracks or burnthrough is permitted for a maximum of 25 cycles.
(b) Missing metal or burning of parent metal	There is no limit to the amount permitted if no material is missing and the burns are not fully through.
(c) Nicks, scores, scratches and dents on platform surface	There is no limit to the number permitted.
(d) Cracks in platform braze joint	Any amount, no separation of the braze joint permitted unless caused by burning.
(e) Bulges or bows	Bulges and bows are not permitted.	Bulges or bows are permitted for a maximum of 25 cycles.

(6) Examine all 18 stage 1 HPT nozzle airfoil trailing edges as you pull the flexscope back around the full 360-degree path.

Subtask 72-00-00-410-258-A

C. Install the borescope plug R into the combustion case as follows:
(1) If used, remove the 956A1603G01 GUIDE TUBES, BORESCOPE from port R.
(2) Verify borescope plug antirotation feature quality:
(a) Holding the borescope plug in one hand and holding the area near the tab, turning the antirotation feature one full revolution.
(b) Replace the borescope plug if there is no clicking sounds when turn the antirotation feature.
(3) Apply graphite grease (Material No.CP2101) or CP2619Never Seez-Pure Nickel, Special to the threads of the port R borescope plug.
(4) Install the port R borescope plug into the HPT case.
(5) Torque the port R borescope plug to between 97 and 83 lbf.in (1.10 and 0.94 m.daN )

5. Close-up
Subtask 72-00-00-410-259-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 72-00-00-440-140-A

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

Subtask 72-00-00-410-260-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 WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 13:03:39 UTC