Borescope Inspection of the Stage 2 High Pressure Turbine (HPT) Nozzle Guide Vanes (NGVs) [CFML]

TASK 72-00-00-290-815-A
Borescope Inspection of the Stage 2 High Pressure Turbine (HPT) Nozzle Guide Vanes (NGVs)

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: 400

1. Reason for the Job
This procedure uses a flexible borescope to do a 360-degree inspection of the stage 2 HPT NGVs.
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
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 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 2 HPT NGV Borescope Inspection

3. Job Set-up
Subtask 72-00-00-941-223-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 72-00-00-010-305-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 72-00-00-040-150-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 72-00-00-010-306-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 72-00-00-010-307-A

A. Removal of the Port S Borescope Plug from the HPT Case
(1) This port gives access for the inspection of the Leading Edge (LE) and Trailing Edge (TE) of the stage 2 HPT NGVs (Ref. AMM TASK 72-00-00-290-812).

Component	Quantity of Segments
Stage 2 HPT NGVs	36

Subtask 72-00-00-290-133-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 2 HPT NGV as follows:

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 stage 2 HPT NGVs.

NOTE: It is optional to use a 6 mm flexscope with a minimum length of 90 in. (2.29 m) without the guide tubes.

(1) If you will use a 956A1603G01 GUIDE TUBES, BORESCOPE, put the guide tube into HPT case port S:
(a) Move the end of the guide tube into the hole in the stage 2 HPT nozzle into the flowpath to inspect the nozzle TE.
(2) Put the BORESCOPE - FLEXIBLE into the guide tube and extend it into the stage 2 HPT flowpath. Continue to move the flexscope in the direction set by the stage 2 HPT nozzle vanes.
(3) 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 2 HPT nozzle. This is necessary to be sure you do a full 360-degree inspection.

(4) Inspection of the stage 2 HPT NGV airfoils:

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Axial cracks in the vane TEs that are more than 0.25 in. (6.35 mm) from the inner platform.	Any amount of axial cracks permitted in the vane TEs if they are not more than 0.06 in. (1.52 mm) in length.	It is permitted to have two cracks for each vane if they are not more than 0.35 in. (8.89 mm) in length, and they are separated from each other by a minimum of 0.25 in. (6.35 mm).
2.All types of cracks in the vane TEs that are less than 0.25 in. (6.35 mm) from the inner platform.	Any amount of cracks permitted if they do not extend more than 0.35 in. (8.89 mm) from the TE.
3.Axial cracks in the vane LEs.	It is permitted to have one axial crack if it is 0.20 in. (5.08 mm) or less in length. No cracks are permitted in Area C if they are parallel to the outer platform.	Any amount of cracks permitted in the vane LEs if there are no separation cracks in the surface coating.
4.Cracks in the vane concave surfaces.	It is permitted to have two cracks for each vane concave surface if they are 0.50 in. (12.70 mm) or less in length.
5.Cracks in the convex side of the vane to the outer platform fillet area.	Cracks are not permitted.
6.Nicks, scores, scratches and dents.	Any amount permitted if they are not more than 0.17 in. (4.32 mm) in diameter and 0.02 in. (0.51 mm) in depth.
7.Oxidation or missing material in the concave and convex surfaces.	It is permitted to have an area that is 0.5 in.2 (322.58 mm2) or less. It is not permitted to have holes that are through the surface material.
8.Oxidation or missing material in the LE.	It is permitted to have a total area that is 0.50 in. (12.70 mm) or less in length and 0.3 in. (7.62 mm) or less in width. If the adjacent stage 1 HPT stator shroud segment EBC is spalled, this additional criterion applies: It is permitted to have a total area 0.1 in.2 (64.5 mm2) or less in Area A. It is not permitted to have a hole through the parent metal, regardless of stage 1 HPT stator shroud EBC condition.	The adjacent stage 1 HPT stator shroud EBC is spalled if the shroud segment is missing complete circumferential EBC in or less than 0.100 in. (2.54 mm) of the TE.
		The over-serviceable limit extension for oxidation or missing material in the LE: A 200 cycle inspection interval is permitted for any amount of oxidation or missing material if there is no hole through the parent metal.
9.Coating that is missing from the airfoil surfaces.	Any amount of missing coating permitted if the adjacent stage 1 HPT stator shroud EBC is not spalled. It is permitted to have a total area 0.5 in.2 (322.6 mm2) or less in Area A if the adjacent stage 1 HPT stator shroud segment EBC is spalled. Any amount of missing coating is permitted outside Area A.	The adjacent stage 1 HPT stator shroud EBC is spalled if the shroud segment is missing complete circumferential EBC in or less than 0.100 in. (2.54 mm) of the TE.
		The over-serviceable limit extension for missing coating in Area A with EBC spall of the adjacent stage 1 HPT stator shroud: A 800 cycle inspection interval is permitted for any amount of missing coating.
10.Material that is missing from the TE.	It is permitted to have an area 0.18 in. (4.57 mm) or less in axial direction by 0.35 in. (8.89 mm) or less in radial direction.
11.Cracks in the vane convex surfaces.	It is permitted to have a maximum of two cracks on each vane with these conditions: The cracks are 0.35 in. (8.89 mm) or less in length. The cracks are separated from the inner and outer platform by 0.35 in. (8.89 mm) or more.

(5) Inspection of the stage 2 HPT NGV inner and outer platforms:

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Cracks.	Any amount of cracks permitted that are 0.35 in. (8.89 mm) in length.	The over-serviceable limit extension for the stage 2 nozzle outer platform cracking: A 1600 cycle inspection interval is permitted with these conditions: Any amount of cracking if there is no hole through the parent metal.
2.Nicks, scores, scratches and dents in the inner and outer platform surfaces.	Any amount of nicks, scores, scratches and dents permitted that are 0.02 in. (0.51 mm) or less in depth. Nicks, scores, scratches and dents that are more than 0.02 in. (0.51 mm) in depth are not permitted.
3.Craze cracks.	Any amount of craze cracks are permitted.
4.Cracks in the outer platform TE.	Any amount of cracks permitted that are 0.30 in. (7.62 mm) or less in length if the cracks do not go into the vane fillet radius.
5.Coating that is missing.	Any amount of missing coating permitted if the adjacent stage 1 HPT stator shroud EBC is not spalled. It is permitted to have a total area 0.5 in.2 (322.6 mm2) or less in Area B if the adjacent stage 1 HPT stator shroud segment EBC is spalled. Any amount of missing coating is permitted outside Area B.	The adjacent stage 1 HPT stator shroud EBC is spalled if the shroud segment is missing complete circumferential EBC in or less than 0.100 in. (2.54 mm) of the TE.
		The over-serviceable limit extension for missing coating in Area B with EBC spall of the adjacent stage 1 HPT stator shroud: A 800 cycle inspection interval is permitted for any amount of missing coating.
6.Heat distress or oxidation on the inner platform.	It is not permitted to have heat distress or burns on the inner platform.
7.Heat distress or oxidation on the outer platform.	Any amount permitted if the adjacent stage 1 HPT stator shroud EBC is not spalled. It is permitted to have a total area 0.1 in.2 (64.5 mm2) or less in Area B if the adjacent stage 1 HPT stator shroud segment EBC is spalled. Any amount of heat distress or oxidation is permitted outside Area B. It is not permitted to have holes that are through the parent metal, regardless of stage 1 HPT shroud EBC condition.	The adjacent stage 1 HPT stator shroud EBC is spalled if the shroud segment is missing complete circumferential EBC in or less than 0.100 in. (2.54 mm) of the TE.
		The over-serviceable limit extension for the stage 2 nozzle outer platform oxidation in Area B with EBC spall of the adjacent stage 1 HPT stator shroud: A 200 cycle inspection interval is permitted for any amount of oxidation or missing material.
		The over-serviceable limit extension for the stage 2 nozzle outer platform oxidation regardless of stage 1 HPT shroud EBC condition: Remove the engine in 10 cycles or less if there is a hole through the parent metal.

(6) Examine all 36 stage 2 HPT nozzle airfoils as you pull the flexscope back around the full 360-degree path.
(7) Carefully withdraw the BORESCOPE - FLEXIBLE and the 956A1603G01 GUIDE TUBES, BORESCOPE, if it was used.
(8) To inspect the LE of the stage 2 nozzles, put the flexscope into port S and extend it into the stage 2 HPT flowpath on the forward side of the stage 2 nozzle. Continue to move the flexscope in the direction set by the stage 2 HPT nozzle vanes.

NOTE: The flexscope will go into the flowpath in the opposite direction compared to when the TE was inspected.

(9) Repeat Para 3 thru Para 7 to inspect the LE of the stage 2 HPT nozzles.

Subtask 72-00-00-410-261-A

C. Installation of the Port S Borescope Plug into the HPT Case
(1) If used, remove the 956A1603G01 GUIDE TUBES, BORESCOPE from port S.
(2) Apply graphite grease (Material No.CP2101) and CP2619Never Seez-Pure Nickel, Special to the threads of the port S borescope plug.
(3) Install the port S borescope plug into the HPT case.
(4) TORQUE the port S borescope plug to between 97 and 83 lbf.in (1.10 and 0.94 m.daN )

5. Close-up
Subtask 72-00-00-410-262-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 72-00-00-440-141-A

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

Subtask 72-00-00-410-263-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 02:50:51 UTC