Borescope/Inspection of the High-Pressure Turbine Shroud [CFMB]

TASK 72-53-00-290-004-A
Borescope/Inspection of the High-Pressure Turbine Shroud

ZONE: 400
FIN: 1000EM1 ** ON A/C NOT FOR ALL
FIN: 1000EM2 ** ON A/C NOT FOR ALL

1. Reason for the Job
Inspection of the high pressure turbine (HPT) shrouds is limited to the areas that can be seen with a flexible borescope, at the spark igniter ports.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 1M(3 FT)
No specific	AR	CAP - PROTECTION
No specific	AR	WARNING NOTICE(S)
856A1321	1	FIBERSCOPE SET
856A1322	1	BORESCOPE-LIGHT SOURCE SET
856A1323	1	MONITOR, RESOLUTION BORESCOPE
856A1351	1	GUIDE TUBE,BORESCOPE-HPT SHROUD

B. Work Zones and Access Panels

ZONE/ACCESS	ZONE DESCRIPTION
400	POWER PLANT, NACELLES AND PYLONS
FOR [1000EM1] (ENGINE-1)
437AL, 438AR, 451AL, 452AR
FOR [1000EM2] (ENGINE-2)
447AL, 448AR, 461AL, 462AR

C. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-040-B	Opening of the Fan Cowl Doors
TASK 71-13-00-410-040-B	Closing of the Fan Cowl Doors
TASK 72-00-00-200-025-A	Over-Serviceable-Limit Extensions
TASK 72-00-00-200-025-A-01	Over-Serviceable-Limit Extensions
TASK 74-21-30-000-002-A	Removal of the Spark Igniter
TASK 74-21-30-400-002-A	Installation of the Spark Igniter
TASK 78-30-00-081-041-B	Make the Thrust Reverser Serviceable after Maintenance
TASK 78-30-00-481-041-B	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-36-00-010-040-B	Opening of the Thrust Reverser Doors
TASK 78-36-00-410-040-B	Closing of the Thrust Reverser Doors
Stage 1 LPT Nozzle and HPT Shroud Inspection
HPT Shroud Thermal Densified Coating Limits

3. Job Set-up
Subtask 72-53-00-941-053-A ** ON A/C NOT FOR ALL

A. Safety Precautions
(1) On the center pedestal, on the ENG panel 115VU:
(a) Put a WARNING NOTICE(S) to tell persons not to start the engine.
(2) Make sure that the engine 1(2) shutdown occurred not less than 5 minutes before you do this procedure.
(3) On the overhead maintenance panel 50VU:
(a) Make sure that the ON legend of the ENG/FADEC GND PWR/1(2) pushbutton switch is off.
(b) Put a WARNING NOTICE(S) to tell persons not to energize the FADEC 1(2).

Subtask 72-53-00-010-056-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowl doors: (Ref. AMM TASK 71-13-00-010-040)
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Put the ACCESS PLATFORM 1M(3 FT) in position.

Subtask 72-53-00-040-053-A ** ON A/C NOT FOR ALL

C. Make the thrust reverser unserviceable (Ref. AMM TASK 78-30-00-481-041).

Subtask 72-53-00-010-059-A ** ON A/C NOT FOR ALL

D. Open the thrust reverser doors: (Ref. AMM TASK 78-36-00-010-040)
(1) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(2) FOR [1000EM2] (ENGINE-2)
461AL 462AR

4. Procedure
Subtask 72-53-00-010-057-A ** ON A/C NOT FOR ALL

A. Remove the spark igniters (Ref. AMM TASK 74-21-30-000-002).
(1) Install the CAP - PROTECTION on the leads and the spark igniters.

Subtask 72-53-00-290-053-A ** ON A/C NOT FOR ALL

B. Do a borescope inspection:

CAUTION: FOLLOW THE INSTRUCTIONS CAREFULLY FOR INSERTING OR REMOVING THE FLEXIBLE BORESCOPE. DOING THE PROCEDURE INCORRECTLY WILL DAMAGE THE TIP CONTROL FUNCTION.

(1) Put the 856A1351 GUIDE TUBE,BORESCOPE-HPT SHROUD (856A1351P01), over the straightening rod.
(2) Push the plastic guide tube and straightening rod into the combustion chamber as far as it will go.
(3) Turn the pointed tab on the plastic guide tube to the rear of the engine and remove the straightening rod from the plastic guide tube.
(4) Connect the 856A1321 FIBERSCOPE SET (856A1321P01/P03/P06), and to the port on the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322P02/P03/P04/P07/P08).
(5) Use the 856A1323 MONITOR, RESOLUTION BORESCOPE (856A1323G01) to make sure borescope and the light source are serviceable. See the Non Destructive Test Manual for this procedure (Ref. NDTM 720000).
(6) Align the borescope lens with one of the plastic tabs on the guide tube and install it into the tube. Make sure that the borescope tip is not moved up or down when putting it into the plastic guide tube.
(7) Push the borescope through the plastic guide tube until the tip comes out of the end of the tube.
(8) Push the tip of the borescope between the nozzle vanes by using the tip deflection control.
(9) Turn on the light source of 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322P02/P03/P04/P07/P08).
(10) Adjust the borescope equipment to obtain maximum clarity of view.
(11) Inspect the HPT Shrouds:

HPT Shroud Thermal Densified Coating Limits ** ON A/C NOT FOR ALL

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.HPT shrouds for:
A.Axial Cracks	Any amount
B.Circumferential Cracks	Any number of circumferential cracks that are not connected and are no more than 1 in. (25.4000 mm) long.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
C.Connected Cracks	Circumferential cracks that are connected to axial cracks cannot be over 0.25 in. (6.3500 mm) long and not less than 0.25 in. (6.3500 mm) from the shroud edge.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
D.Burning, erosion or chipped/missing TDC exposing the backstrip	Any amount if the shroud does not drop into the flowpath.
E.Split-Line Aft Corners	Any amount of circumferential missing or distorted material less than 0.200 in. (5.08 mm) and axial missing or distorted material less than 0.400 in. (10.16 mm) measured from the edge of the shroud.
F.Split-line forward corners	Any amount of missing material permitted in or less than 0.250 in. (6.35 mm) in axial direction from the leading edge and in or less than 0.080 in. (2.03 mm) in circumferential direction from shroud side walls.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
G.Split-line other areas	Any amount of missing material permitted if area (A) is below 0.013 in.2 (8.387 mm2) and distance from original contour in circumferential direction (d) is below 0.080 in. (2.03 mm).	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
H.Missing, cracked or displaced shroud axial seals	Any amount
J.Rubs/wear	Any amount
K.Distortion	Any amount, if shroud is not in the flowpath.
L.Burn through on rub land (this include holes through the backstrip)	Not serviceable	See limit extensions (Ref. AMM TASK 72-00-00-200-025).

Subtask 72-53-00-080-053-A ** ON A/C NOT FOR ALL

C. When the inspection is completed, turn off the light source, 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P02/P03/P04/P07/P08) and remove the 856A1321 FIBERSCOPE SET (856A1321P01/P03/P06) and 856A1351 GUIDE TUBE,BORESCOPE-HPT SHROUD (856A1351P01).

Subtask 72-53-00-410-056-A ** ON A/C NOT FOR ALL

D. Install the spark igniters (Ref. AMM TASK 74-21-30-400-002), after removing the CAP - PROTECTION from the leads and the spark igniters.

5. Close-up
Subtask 72-53-00-410-057-A ** ON A/C NOT FOR ALL

A. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the thrust reverser doors: (Ref. AMM TASK 78-36-00-410-040)
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR

Subtask 72-53-00-440-053-A ** ON A/C NOT FOR ALL

B. Make the thrust reverser serviceable (Ref. AMM TASK 78-30-00-081-041).

Subtask 72-53-00-410-059-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Close the fan cowl doors: (Ref. AMM TASK 71-13-00-410-040)
(a) FOR [1000EM1] (ENGINE-1)
437AL 438AR
(b) FOR [1000EM2] (ENGINE-2)
447AL 448AR
(2) Remove the access platform(s).
(3) Remove the WARNING NOTICE(S).

[Rev.10 from 2021] 2026.04.01 02:43:02 UTC