Borescope Inspection of the HPT Blades (from the Front and the Rear) [CFMI]

TASK 72-52-00-290-001-A
Borescope Inspection of the HPT Blades (from the Front and the Rear)

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
Refer to the MPD TASK: 725000-C1
BORESCOPE INSPECTION OF HPT BLADES (FROM THE FRONT AND THE REAR)
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 (Aft Looking Forward) borescope ports (S17 and S18). 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.

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 63 and 57 lbf.in (0.71 and 0.64 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 tecksol
(Material No.CP2584)	degreasol 99 R
(Material No.CP2619)	nickel never-seez
(Material No.CP2656)	mag-chem skysol
(Material No.CP8001)	safetywire

C. 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

D. Referenced Information

REFERENCE	DESIGNATION
TASK 71-13-00-010-040-A	Opening of the Fan Cowl Doors
TASK 71-13-00-410-040-A	Closing of the Fan Cowl Doors
TASK 72-00-00-200-005-A	Over-Serviceable-Limit Extensions
TASK 72-42-00-290-001-A	Borescope Inspection of the Combustion Chamber Liners and Dome Area
TASK 72-52-00-290-002-A	Borescope Inspection of the High Pressure Turbine Rotor Blades (from the front)
TASK 72-63-00-000-004-A	Removal of the Handcranking Drive Cover
TASK 72-63-00-400-004-A	Installation of the Handcranking Drive Cover
TASK 78-30-00-081-041-A	Make the Thrust Reverser Serviceable after Maintenance
TASK 78-30-00-481-041-A	Make the Thrust Reverser Unserviceable for Maintenance
TASK 78-36-00-010-040-A	Opening of the Thrust Reverser Doors
TASK 78-36-00-410-040-A	Closing of the Thrust Reverser Doors
TASK 80-11-10-000-001-A	Removal of the Pneumatic Starter
TASK 80-11-10-400-001-A	Installation of the Pneumatic Starter
NTM 720000
HPT Blade Inspection
Rub Wear Notches on the Blade Tip and Cracks
HPT Blade Inspection Areas
Core Rotate Drive Motor Installation
HPT Blade Trailing Edge Inspection

3. Job Set-up
Subtask 72-52-00-941-050-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 72-52-00-010-050-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 72-52-00-040-050-A ** ON A/C NOT FOR ALL

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

Subtask 72-52-00-010-052-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 72-52-00-869-050-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 (Ref. AMM TASK 72-63-00-000-004) from the core rotation pad on the left side of the accessory gearbox (AGB), opposite the starter.
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 80-11-10-000-001).
2 Install 856A1488 MOTOR, DRIVE - CORE ENGINE ROTATION (856A1488P01 or P02) into the accessory gearbox (AGB) starter drive pad. Align the drive shaft of the drive motor with the starter 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 (44.9 USgal (170 l) per minute).
(3) Remove one of the borescope plugs (S17 or S18) 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 (856A1320P04 or P05) and to the port on the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322P03, P04, or P07).
(5) Put the rigid borescope of the 856A1320 BORESCOPE-KIT (856A1320P04 or P05), into the port and turn on the light source of 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322P03 or P04).

Subtask 72-52-00-290-050-A ** ON A/C NOT FOR ALL

B. Borescope Inspection of the HPT Blades
(1) Look at the trailing edge, tip concave and convex side of the HPT blades as follows:

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

(a) Adjust the borescope equipment to obtain maximum clarity of view.
(b) Turn the HPT rotor clockwise (aft looking forward). Stop the rotor at each blade to make sure all of the defects can be seen.
1 To turn the HPT rotor clockwise, the rotation pad drive must be turned Counter Clockwise (CCW).
(c) Inspect the HPT blades (from the rear) 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 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 tecksol (Material No.CP2566) or degreasol 99 R (Material No.CP2584) or mag-chem skysol (Material No.CP2656) or an equivalent substitue to remove light engine deposits.

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).

If a HPT blade has impact damage, you must do a 360 degree combustor borescope inspection to look for combustor distress (Ref. AMM TASK 72-42-00-290-001).

INSPECT/CHECK	MAXIMUM SERVICEABLE LIMITS	REMARKS
1.Trailing edge for:
A.Cracks in area C and root fillet. Make sure that discoloration, scratches or marks are not seen as cracks. Rub Wear Notches on the Blade Tip and Cracks ** ON A/C NOT FOR ALL	One permitted, 0.1 in. (2.54 mm) long.	See limit extensions (Ref. AMM TASK 72-00-00-200-005).
B.Cracks in area B.	Not serviceable.	See limit extensions (Ref. AMM TASK 72-00-00-200-005).
C.Cracks in area A.	One permitted, 0.1 in. (2.54 mm).	See limit extensions (Ref. AMM TASK 72-00-00-200-005).
D.Missing material. Burning or holes in tip and area A. See figure "HPT Blade Trailing Edge Inspection". HPT Blade Trailing Edge Inspection ** ON A/C NOT FOR ALL	Any amount down to the top of the first slot below the tip shelf. If the missing material is to the bottom of the first slot and aft of the forward edge of the slot (area 1), repeat borescope inspection every 200 cycles. If the missing material is forward of the forward edge of the slots but less than 0.50 in. (12.70 mm) axially or to the bottom of the 4th trailing edge slot (area 2), repeat boroscope inspection every 50 cycles.	See limit extensions (Ref. AMM TASK 72-00-00-200-005).
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 and C and root fillet.	Three permitted, 0.057 in. (1.45 mm) long. Nicks and dents must be separated by 0.125 in. (3.17 mm) minimum.
K.Bent material at the tip.	Any amount.
2.Blade tip for: NOTE: There are four notched blades in the HPT rotor to show the amount of blade tip rubbing.
A.Radial cracks on convex side.	Any number permitted, 0.15 in. (3.81 mm) maximum radial length.	See limits extension (Ref. AMM TASK 72-00-00-200-005).
B.Radial cracks on concave side.	Any number up to 0.7 in. (17.78 mm) maximum length.	See limit extensions (Ref. AMM TASK 72-00-00-200-005).
C.Bent, curled or missing material.	Any amount above the tip shelf.
3.Convex and concave 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 and root fillet.	Three permitted, 0.05 in. (1.27 mm) long. Nicks and dents must be separated by 0.125 in. (3.17 mm) minimum.
D.Cracks.	Not serviceable.
4.Blade airfoil for:
A.Distortions or evidence of burning or melting.	Not serviceable.
B.Missing codep coating.	Any amount.

(2) Record the estimated depth of the wear notches on the four notched blades.

Rub Wear Notches on the Blade Tip and Cracks ** ON A/C NOT FOR ALL

NOTE: 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.

(3) When the inspection is completed, turn off the 856A1322 BORESCOPE-LIGHT SOURCE SET (856A1322 P03, P04 or P07) and remove the 856A1320 BORESCOPE-KIT (856A1320 P04 or P05).
(4) Apply a small amount of graphite grease (Material No.CP2101) or nickel never-seez (Material No.CP2619) to the borescope plug threads and pressure faces.
(5) Install the borescope plug(s) and TORQUE to between 63 and 57 lbf.in (0.71 and 0.64 m.daN )

WARNING: USE PROTECTIVE GOGGLES AND GLOVES WHEN YOU REMOVE OR INSTALL LOCKWIRE. EACH TIME YOU CUT LOCKWIRE, REMOVE AND DISCARD IT IMMEDIATELY. LOOSE LOCKWIRE CAN CUT YOU OR MAKE YOU BLIND, AND/OR CAN CAUSE DAMAGE.

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) Safety the plugs with safetywire (Material No.CP8001) .
(6) Do a borescope inspection of the HPT blades from the front (Ref. AMM TASK 72-52-00-290-002).
(7) Remove the tools used to rotate the core as follows:
(a) If the breaker bar is installed, see steps 4.B.(7)(a)1_ and 4.B.(7)(a)2_. If the drive motor is installed, see steps 4.B.(7)(a)3_ and 4.B.(7)(a)4_.
1 Remove the SPEED BRACE 3/4 IN - SQUARE DRIVE and the BAR LENGTH 60 CM (2 FT) BREAKER from the core rotation drive pad.
2 Install the handcranking drive pad cover (Ref. AMM TASK 72-63-00-400-004).
3 Remove the drive motor from the starter pad of the AGB.
4 Install the starter (Ref. AMM TASK 80-11-10-400-001).

5. Close-up
Subtask 72-52-00-410-050-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 cowl doors: (Ref. AMM TASK 78-36-00-410-040)
(3) FOR [1000EM1] (ENGINE-1)
451AL 452AR
(4) FOR [1000EM2] (ENGINE-2)
461AL 462AR

Subtask 72-52-00-440-050-A ** ON A/C NOT FOR ALL

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

Subtask 72-52-00-410-052-A ** ON A/C NOT FOR ALL

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

[Rev.10 from 2021] 2026.04.01 02:39:33 UTC