Borescope Inspection of HPT Blades (from the front and the rear) [CFMB]

TASK 72-52-00-290-001-B-01
Borescope Inspection of HPT Blades (from the front and the rear)

1. Reason for the Job
Refer to the MPD TASK: 725000-C1
BORESCOPE INSPECTION OF HPT BLADES (FROM THE FRONT AND THE REAR)
This TASK is applicable for /P, /3 and /3 PIP engines.
Inspection of the High Pressure Turbine (HPT) blades from the rear is limited to the areas that can be seen with a rigid borescope, at the 5:30 and 8:30 o'clock borescope ports (S16 and S17). The borescope ports at the 5:30 and 8:30 o'clock positions are located immediately in front of the combustion case aft flange. Inspection of the HPT blades from the front is accomplished with a flexible borescope through the spark igniter ports (S10 and S11) of the combustion case.

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	AR	ACCESS PLATFORM 1M(3 FT)
No specific	AR	BAR LENGTH 60 CM (2 FT) BREAKER
No specific	AR	SPEED BRACE 3/4 IN - SQUARE DRIVE
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 65 and 59 lbf.in (0.73 and 0.67 m.daN )
856A1320	1	BORESCOPE-KIT
856A1322	1	BORESCOPE-LIGHT SOURCE SET
856A1323	1	MONITOR, RESOLUTION BORESCOPE
856A1488	1	MOTOR, DRIVE - CORE ENGINE ROTATION

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.CP1039)	acetone
(Material No.CP1041)	isopropyl alcohol
(Material No.CP2011)	stoddard solvent
(Material No.CP2101)	graphite grease
(Material No.CP2559)	ardrox 552
(Material No.CP2560)	turco ind 79
(Material No.CP2566)	mag-chem teksol
(Material No.CP2584)	degreasol 99 R
(Material No.CP2656)	mag-chem skysol
(Material No.CP8001)	lockwire 0.032 in. (0.8 mm) dia.

C. Work Zones and Access Panels

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

D. 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 72-42-00-290-007-A	Borescope Inspection of the Inner Cowl Bolts of the Combustion Chamber
TASK 72-42-00-290-041-A	Borescope Inspection of the Combustion Chamber Liners and Dome Area (SAC engine)
TASK 72-42-00-290-041-A-01	Borescope Inspection of the Combustion Chamber Liners and Dome Area (DAC engine NON /P only)
TASK 72-42-00-290-041-A-02	Borescope Inspection of the Combustion Chamber Liners and Dome Area (DAC engine /P only)
TASK 72-52-00-290-004-A	Borescope Inspection of the High Pressure Turbine Rotor Blade (from the front)
TASK 72-52-00-290-004-A-01	Borescope Inspection of the High Pressure Turbine Rotor Blade (from the front)
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 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)
HPT Blade Inspection (Only Applicable /P and /3 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)
Inspection for HPT AFT Blade Seal Wire Protrusion

3. Job Set-up
Subtask 72-52-00-941-055-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 72-52-00-010-060-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).

Subtask 72-52-00-040-055-A ** ON A/C NOT FOR ALL

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

Subtask 72-52-00-010-061-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 72-52-00-869-052-A ** ON A/C NOT FOR ALL

A. Prepare for inspection:
(1) Use the 856A1323 MONITOR, RESOLUTION BORESCOPE (856A1323G01) to make sure that the borescope or fiberscope and 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 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 one of the borescope plugs (S16 or S17) found immediately in front of the aft flange of the combustion case at the 5:30 and 8:30 o'clock positions.
(4) Connect the fiber light cable to the 856A1320 BORESCOPE-KIT (856A1320 P04 or P05), and to the port on the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03, P04 or P07).
(5) Put the rigid borescope of the 856A1320 BORESCOPE-KIT (856A1320 P04 or P05) into the borescope port and turn on the light source of 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03 or P04).

Subtask 72-52-00-290-055-A ** ON A/C NOT FOR ALL

B. Do a borescope inspection:
(1) Look at the trailing edge, tip concave and convex sides of the HPT blades as follows:
(a) Adjust the borescope equipment to obtain maximum clarity of view.
(b) 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 counterclockwise (CCW).

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 stoddard solvent (Material No.CP2011) or acetone (Material No.CP1039) or isopropyl alcohol (Material No.CP1041) or ardrox 552 (Material No.CP2559) or turco ind 79 (Material No.CP2560) or mag-chem teksol (Material No.CP2566) or degreasol 99 R (Material No.CP2584) or mag-chem skysol (Material No.CP2656) or an equivalent substitute to remove light engine deposits.

NOTE: If a HPT blade has impact damage, you must do a 360-degree combustor borescope inspection to look for combustor distress (Ref. AMM TASK 72-42-00-290-041) and inner cowl bolts (Ref. AMM TASK 72-42-00-290-007).

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

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Trailing edge for: NOTE: Casting core lines are permitted.
A.Cracks in area B and C including root filet. Make sure that discoloration, scratches or marks are not seen as cracks.	For a crack up to 0.12 in. (3.0 mm) in length, the maximum reinspection interval is 400 cycles. For a crack more than 0.12 in. (3.0 mm) and up to 0.20 in. (5.1 mm) in length, the maximum reinspection interval is 200 cycles.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
B.Cracks in area A.	One crack up to 0.10 in. (2.5 mm) in length is permitted. For a crack more than 0.10 in. (2.5 mm) but less than 0.20 in. (5.1 mm) in length, do the inspection again in or less than 500 cycles.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
C.Missing material. Burning, or holes in tip and area A.	No limit, as long as the missing material is not more than 0.50 in. x 0.50 in. (12.7 mm x 12.7 mm).	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
D.Missing thermal barrier coating.	Any amount.
E.Plugged air passages in area C.	Not serviceable.
F.Plugged air passages in area B.	One permitted.
G.Plugged air passages in area A.	One permitted.
H.Nicks and dents, area A.	Any amount, if there are no cracks or torn metal.
J.Nicks and dents, areas B, C, and root fillet.	No limit, as long as the nicks and dents are not more than 0.1 in. (2.54 mm) long. For areas B and C: If the nicks and dents are more than 0.1 in. (2.54 mm) but not more than 0.2 in. (5.08 mm) long, repeat this inspection within 200 cycles.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
K.Bent material at the tip, areas B or C.	Any amount.
2.HPT aft blade retainer outer seal wire protrusion at seal wire ends.	HPT aft blade retainer outer seal wire protrusion is acceptable if it occurs at no more than two locations.	For all other non-seal wire end protrusions contact CFM.
3.Blade tip for: NOTE: There can be 2 or 4 notched blades in the HPT rotor that are used to show blade tip wear. The blade tip wears as it rubs against the shroud. The number of notches that can be seen is an indication of tip wear. It is possible that all tip notches can be gone because of wear. Missing notches have no effect on the serviceable condition of the blade.
A.Radial cracks on convex side not within 0.5 in. (12.7 mm) of trailing edge.	Any number, up to 0.15 in. (3.81 mm) long.	See limits extension (Ref. AMM TASK 72-00-00-200-025).
B.Radial cracks on concave side not within 0.5 in. (12.7 mm) of trailing edge.	Any number, up to 0.7 in. (17.78 mm) long.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
C.Bent, curled or missing material.	Any amount, above tip shelf.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
D.Radial cracks (convex or concave) within 0.50 in. (12.7 mm) of trailing edge.	Any amount.
E.Missing thermal barrier coating.	Any amount.
4.Convex and concave surfaces for:
A.Nicks or dents, area A.	Any number, 0.25 in. (6.35 mm) long.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
B.Nicks or dents, area B.	Any number, 0.1 in. (2.54 mm) long.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
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.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).
D.Cracks in other areas.	Not serviceable.
E.Missing thermal barrier coating.	Any amount.
5.Blade airfoil for:
A.Distortions or evidence of burning or melting.	Not serviceable.	See limit extensions (Ref. AMM TASK 72-00-00-200-025).

(2) When the inspection is complete, turn off the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03, P04 or P07) and remove the 856A1320 BORESCOPE-KIT (856A1320 P04 or P05).
(3) Apply a small amount of graphite grease (Material No.CP2101) to the borescope plug threads and pressure faces.
(4) Install the borescope plug.

CAUTION: MAKE SURE YOU INSTALL THE CORRECT BORESCOPE PLUGS. THE TWO LPT STAGE 1 NOZZLE BORESCOPE PLUGS HAVE A STEM FEATURE. INCORRECT INSTALLATION OF THESE PLUGS IN THE COMBUSTION CASE WILL CAUSE THE STEM TO BE BURNED AWAY BY COMBUSTION GASSES.

(a) Install the borescope plug(s) and TORQUE to between 65 and 59 lbf.in (0.73 and 0.67 m.daN )

.
(5) Safety the plugs with CP8001lockwire 0.032 in. (0.8 mm) dia..
(6) Do a borescope inspection of the HPT blades from the front (Ref. AMM TASK 72-52-00-290-004).
(7) 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. (0.60 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 72-52-00-410-060-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 without making thrust reverser serviceable (Ref. AMM TASK 78-36-00-410-040):
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR

Subtask 72-52-00-440-055-A ** ON A/C NOT FOR ALL

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

Subtask 72-52-00-410-061-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 WARNING NOTICE(S).
(3) Remove the access platform(s).

[Rev.10 from 2021] 2026.04.01 02:42:55 UTC