Borescope Inspection of the High Pressure Turbine Rotor Blade (from the front) [CFMB]

TASK 72-52-00-290-004-A-01
Borescope Inspection of the High Pressure Turbine Rotor Blade (from the front)

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.

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

1. Reason for the Job
This TASK is applicable for /P, /3 and /3 PIP engines.
Inspection of the high pressure turbine (HPT) blades from the front is limited to the areas that can be seen with a flexible borescope installed at the spark igniter ports (S10 and S11).

NOTE: There are 80 HPT blades installed in the rotor.

NOTE: There are 76 HPT blades installed in the rotor for PIP engines (POST SB 72-0821).

2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	1	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE
No specific	AR	BAR LENGTH 60 CM (2 FT) BREAKER
No specific	AR	CAP - PROTECTION
No specific	AR	SPEED BRACE 3/4 IN - SQUARE DRIVE
No specific	AR	WARNING NOTICE(S)
856A1310	1	KIT, BORESCOPE GUIDE - HP TURBINE
856A1321	1	FIBERSCOPE SET
856A1322	1	BORESCOPE-LIGHT SOURCE SET
856A1323	1	MONITOR, RESOLUTION BORESCOPE
856A1488	1	MOTOR, DRIVE - CORE ENGINE ROTATION

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 72-42-00-290-005-A	Inspection of the Combustion Chamber and HPT Nozzle Following a Birdstrike/FOD (SAC engine)
TASK 72-42-00-290-005-A-01	Inspection of the Combustion Chamber and HPT Nozzle Following a Birdstrike/FOD (DAC engine)
TASK 72-63-00-000-002-A	Removal of the Handcranking Drive Cover
TASK 72-63-00-400-002-A	Installation of the Handcranking Drive Cover
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
TASK 80-11-10-000-002-A	Removal of the Pneumatic Starter
TASK 80-11-10-400-002-A	Installation of the Pneumatic Starter
NTM 720000
Inspection of the HPT Blade (Only applicable for SAC Engines)
Core Rotation Drive Motor Installation
HP Blade Cracks (Applicable /P and /3 Engines)
High-Pressure Turbine Blade Inspection Areas (Only Applicable /P and /3 Engines)
High-Pressure Turbine Blade (Applicable /P, /3 and /3 PIP Engines)
HP Blade Cracks (Applicable /3 Engines POST CFM SB 72-0821)
HPT Blade Inspection (Applicable /3 Engines POST CFM SB 72-0821)
High-Pressure Turbine Blade Inspection Areas (Applicable /3 Engines POST CFM SB 72-0821)
Inspection of the HPT Blade (Only applicable for DAC Engines)

3. Job Set-up
Subtask 72-52-00-941-054-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 72-52-00-010-058-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowls doors: (Ref. AMM TASK 71-13-00-010-040)
(2) FOR [1000EM1] (ENGINE-1)
437AL, 438AR
(3) FOR [1000EM2] (ENGINE-2)
447AL, 448AR.
(4) Put the ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE in position.

Subtask 72-52-00-040-054-A ** ON A/C NOT FOR ALL

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

Subtask 72-52-00-010-059-A ** ON A/C NOT FOR ALL

D. Open the thrust reverser cowl 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 72-52-00-290-054-A ** ON A/C NOT FOR ALL

A. Prepare for inspection:
(1) Use the 856A1323 MONITOR, RESOLUTION BORESCOPE (856A1323G01) to make sure the borescope and the light source are serviceable. See the Non-Destructive Test Manual for this procedure NTM 720000.
(2) Install the tools to turn the core engine.

NOTE: The core engine may be turned using a breaker bar (see step (a)) or with a drive motor (see step (b)).

(a) To turn the core manually with a breaker bar, do the steps that follow:
1 Remove the handcranking drive cover from the core rotation pad on the left side of the accessory gearbox (AGB), opposite the starter (Ref. AMM TASK 72-63-00-000-002).
2 Install a SPEED BRACE 3/4 IN - SQUARE DRIVE with a BAR LENGTH 60 CM (2 FT) BREAKER into the handcranking drive pad. When you do the borescope inspection, turn the core engine clockwise (CW, aft looking forward).

NOTE: To turn the core engine CW, the handcranking drive must be turned counterclockwise (CCW).

(b) To turn the core with a drive motor, do the steps that follow:
1 Remove the starter (Ref. AMM TASK 80-11-10-000-002).
2 Install the 856A1488 MOTOR, DRIVE - CORE ENGINE ROTATION (856A1488 P01 or P02) into the accessory gearbox (AGB) starter drive pad. Align the drive shaft of the drive motor with the starter drive pad drive shaft and engage the splines.

NOTE: The tool must be installed in the horizontal position with the air hoses to the rear.

3 Turn the tool until the captive bolts align with the gearbox bolt holes.
4 Tighten the two captive bolts by hand.
5 Install the clamp to secure the drive motor.
6 Attach the foot or hand control air hoses to the quick disconnects on the tool.
7 Connect the air supply to the drive motor. The air supply must be capable of 100 psi (6.9 bar). The air supply must be lubricated and filtered at 6 SCFM (170 L/minute).
(3) Remove either one of the spark igniters (Ref. AMM TASK 74-21-30-000-002).
(4) Install the CAP - PROTECTION on the lead and the spark igniter.
(5) Put the 856A1310 KIT, BORESCOPE GUIDE - HP TURBINE (856A1310G01) over the straightening rod.
(6) Push the plastic guide tube and straightening rod into the combustion chamber through the spark igniter port (S10 or S11) as far as it will go.
(7) 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.
(8) Installation of the borescope:

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

(a) Connect the fiber light cable to the 856A1321 FIBERSCOPE SET (856A1321 P01 or P03) to the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03, P04 or P07).
(b) 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.
(c) Push the borescope through the plastic guide tube until the tip comes out of the end of the tube.
(d) Push the tip of the borescope between the nozzle vanes by using the tip deflection control.
(e) Turn on the light source of the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03 or P04).
(f) Adjust the borescope equipment to get maximum clarity of view.
(9) Turn the HPT rotor CW (aft looking forward). Stop the rotor at each blade to make sure all of the defects can be seen.

NOTE: To turn the HPT rotor CW, the rotation pad drive must be turned CCW.

(10) Inspect the HPT blades (from the front) and use the limits that follow:

NOTE: It is not easy to visually tell when cooling holes are plugged. Cooling holes which are apparently plugged are permitted if any cracking, erosion or burning is within serviceable limits.

NOTE: Crack indications which are not completely identified may be sprayed with solvent (CP2011) or an equivalent substitute to remove light engine deposits.

NOTE: When a HPT blade has impact damage, you must do a 360 degree combustor borescope inspection to look for combustor distress (Ref. AMM TASK 72-42-00-290-005).

NOTE: For purposes of estimating the size of any distress, the radial spacing of the trailing edge slots is approximately 0.1 in. (2.54 mm).

NOTE: After long exposure, once protective coatings are consumed, the base metal can start to oxidize. This oxidation is usually black or very dark in color and usually has a rough surface.

NOTE: After you have removed the igniter plug for access, if you see non-serviceable damage or fragmentation of the igniter plug tip, replace it and make a note of the findings in the borescope findings report. Then pay special attention to the HPT Blades for impact damage, especially on the airfoil leading edge and outer/forward convex airfoil regions.

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Leading edge for:
A.Axial and radial cracks in area A.	Any number 0.05 in. (1.27 mm) long if they do not connect more than 2 holes.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
B.Axial and radial cracks in areas B and C, that include root radius that do not intersect nose or gill holes.	Not permitted.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
C.Nicks and dents in area A.	Any amount.
D.Nicks and dents in area B.	Any amount.
E.Nicks and dents in area C, including root radius.	3 permitted, 0.05 in. (1.27 mm) long. Nicks and dents must be separated by 0.125 in. (3.17 mm) minimum.
F.Axial nose or concave gill hole (row 6) cracks, areas B and C.	Not serviceable.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
G.Axial convex gill hole (row 1) cracks in area B and C.	Permitted with these conditions: a) Cracks are not more than 0.050 in. (1.27 mm). b) Do the inspection again after each 100 cycles. NOTE: Cracks within gill hole diffuser are to be treated as separate from cracks that extend toward leading edge. Limits are applicable to each crack independently, and crack length must not be put together. See sheet 2 of the figure: High-Pressure Turbine Blade (Applicable /P, /3 and /3 PIP Engines) ** ON A/C NOT FOR ALL	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
H.Radial nose or gill hole cracks, areas B and C.	None allowed in area C, one permitted, 0.03 in. (0.76 mm) long in area B.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
J.Dirt or environmental build-up.	Any amount.
K.Missing thermal barrier coating.	Any amount.
L.Through wall hole in area A and area B.	Permitted with these conditions: a) Cavity 2 is not exposed. NOTE: Cavity 2 will only be exposed if the internal cavity is visible and the damage is aft of cooling row 1, convex gill hole row, or aft of cooling row 6, concave gill hole row. b) Not more than two blades have a through wall hole. c) Do the inspection again after each 100 cycles. After a minimum of four inspections, if the size of the through wall hole has not increased, increase the inspection interval to be in or less than every 400 cycles. After a minimum of four inspections, if the size of the through wall hole has increased, maintain the inspection interval at 100 cycles. After a minimum of four inspections at 400 cycle intervals, if the size of the through wall hole has not changed, increase the inspection interval to within every 1600 cycles.	Refer to limit extensions (Ref. AMM TASK 72-00-00-200-025).
M.Through wall hole in area C.	Permitted with these conditions: a) Engines covered by SB CFM 72-0644, SB CFM 72-0849 or SB CFM 72-0913. b) Hole size less than 0.070 in. (1.8 mm) diameter or 0.0038 in.2 (2.45 mm2) equivalent area. Do the inspection again after each 100 cycles.	Refer to limit extensions (Ref. AMM TASK 72-00-00-200-025).
N.Discoloration and oxidation.	NOTE: After long exposure, once protective coatings are consumed, the base metal can start to oxidize. This oxidation is usually black or very dark in color and usually has a rough surface. NOTE: Once there is leading edge oxidation, you are more likely to see cracks at cooling row 1, (convex gill hole row) holes 2, 3 and 4 up from the platform. Make sure that your borescope orientation provides good visibility of these holes. a) Discoloration without oxidation is permitted. b) Oxidation is permitted with reduced inspection interval as follows: 1_ If you see oxidation with continuous radial length of 0.50 in. (12.7 mm) or less, do the inspection again after each 400 cycles. 2_ If the oxidation has a continuous radial length of more than 0.50 in. (12.7 mm), do the inspection again after each 200 cycles.
2.Blade tip for:
NOTE: There are 2 notched blades in the HPT rotor to show the amount of blade tip rubbing. If the notches can or cannot be seen, the condition is serviceable.
A.Radial cracks on convex side not within 0.50 in. (12.7 mm) of trailing edge.	Any number up to 0.15 in. (3.8 mm) max radial length.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
B.Radial cracks on concave side not within 0.50 in. (12.7 mm) of trailing edge.	Any number up to 0.7 in. (17.8 mm) max length.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
C.Radial cracks (convex and/or concave) within 0.50 in. (12.7 mm) of trailing edge.	Any amount.
D.Bent, curled or missing material.	Permitted, if the damage is in the tip area and none of the blade internal cavities are exposed.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
E.Missing thermal barrier coating.	Any amount.
3.Concave and convex surfaces for:
A.Nicks or dents, area A.	Any number 0.25 in. (6.35 mm) long.
B.Nicks or dents, area B.	Any number, 0.1 in. (2.54 mm) long.
C.Nicks or dents, area C.	3 permitted, 0.05 in. (1.27 mm) long. Nicks and dents must be separated by 0.125 in. (3.17 mm) minimum.
D.Cracks, other areas.	Not serviceable.
E.Missing thermal barrier coating.	Any amount.

(11) When the inspection is completed, turn off the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03, P04 or P07) and remove the 856A1321 FIBERSCOPE SET (856A1321 P01 or P03) and guide tube.
(12) Install the spark igniter (Ref. AMM TASK 74-21-30-400-002).
(13) Remove the tools used to rotate the core as follows:

NOTE: If the breaker bar is installed see steps (a) and (b). If the drive motor is installed see steps (c) and (d).

(a) Remove the 0.75 in. (19.05 mm) square drive socket and 2 ft. (0.6 m) breaker bar from the core rotation drive pad.
(b) Install the handcranking drive pad cover (Ref. AMM TASK 72-63-00-400-002).
(c) Remove the drive motor from the starter pad of the AGB.
(d) Install the starter (Ref. AMM TASK 80-11-10-400-002).

5. Close-up
Subtask 72-52-00-410-058-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 72-52-00-440-054-A ** ON A/C NOT FOR ALL

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

Subtask 72-52-00-410-059-A ** ON A/C NOT FOR ALL

C. Close Access
(1) Close the fan cowls (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 02:42:58 UTC