Borescope Inspection of the Low Pressure (LP) Turbine [IAE]

TASK 72-00-00-200-012-A
Borescope Inspection of the Low Pressure (LP) Turbine

WARNING: BE CAREFUL WHEN YOU USE CONSUMABLE MATERIALS. OBEY THE MATERIAL MANUFACTURER'S INSTRUCTIONS AND YOUR LOCAL REGULATIONS.

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 gives the procedure for the borescope inspection of the stage 3 LP turbine. A description of the types of damage that may be seen is given in 70-52-11, Definition of Damage.
2. Job Set-up Information
A. Fixtures, Tools, Test and Support Equipment

REFERENCE	QTY	DESIGNATION
No specific	AR	ACCESS PLATFORM 2M (6 FT) - ADJUSTABLE
No specific	AR	WARNING NOTICE(S)
No specific	Torque wrench: range to between 72 and 62 lbf.in (0.81 and 0.70 m.daN )
IAE6F10408	1	EQUIPMENT-BORESCOPE

B. Consumable Materials

REFERENCE	DESIGNATION
(Material No.V01-005)	solvent cleaner
(Material No.V02-119)	corrosion resistant steel lockwire
(Material No.V10-129A)	anti-seize paste
(Material No.14SBA1)	Textile-Lint free Cotton -

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 70-23-11-911-013-A	General Torque Tightening Techniques
TASK 71-13-00-010-010-A	Opening of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 71-13-00-410-010-A	Closing of the Fan Cowls 437AL(447AL),438AR(448AR)
TASK 78-30-00-040-012-A	Deactivation of the Thrust Reverser Hydraulic Control Unit (HCU) for Ground Maintenance
TASK 78-30-00-440-012-A	Re-activation of the Thrust Reverser Hydraulic Control Unit (HCU) after Ground Maintenance
TASK 78-32-00-010-010-A	Opening of the Thrust Reverser Halves
TASK 78-32-00-410-010-A	Closing of the Thrust Reverser Halves
LP Turbine Borescope Inspection
LP Turbine Borescope Inspection
Stage 3 Turbine Blades - Borescope Inspection
Stage 3 Turbine Blades - Borescope Inspection
Stage 3 Turbine Blades - Borescope Inspection
Stage 3 Turbine Blades - Borescope Inspection
Stage 3 Turbine Vane - Borescope Inspection
LP Turbine Borescope Inspection

3. Job Set-up
Subtask 72-00-00-941-081-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 72-00-00-010-089-A ** ON A/C NOT FOR ALL

B. Get Access
(1) Open the fan cowls (Ref. AMM TASK 71-13-00-010-010):
(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 72-00-00-040-069-A ** ON A/C NOT FOR ALL

C. Deactivate the thrust reverser.

WARNING: MAKE SURE THAT THE THRUST REVERSER HYDRAULIC CONTROL UNIT (HCU) IS DEACTIVATED BEFORE YOU DO WORK ON OR AROUND THE THRUST REVERSER. IF THE HCU IS NOT DEACTIVATED, THERE IS A RISK OF UNWANTED THRUST REVERSER OPERATION WHICH CAN CAUSE INJURY TO PERSONS AND/OR DAMAGE TO EQUIPMENT.

(1) Deactivate the thrust reverser hydraulic control unit (HCU) (Ref. AMM TASK 78-30-00-040-012).

Subtask 72-00-00-010-109-A ** ON A/C NOT FOR ALL

D. Open the thrust reverser halves (Ref. AMM TASK 78-32-00-010-010):
(1) FOR [1000EM1] (ENGINE-1)
451AL 452AR.
(2) FOR [1000EM2] (ENGINE-2)
461AL 462AR.

Subtask 72-00-00-480-058-A ** ON A/C NOT FOR ALL

E. Prepare the IAE6F10408 EQUIPMENT-BORESCOPE for use as given in the manufacturers instructions.

4. Procedure
Subtask 72-00-00-010-097-A ** ON A/C NOT FOR ALL

A. Remove the LP turbine blanking plugs

LP Turbine Borescope Inspection ** ON A/C NOT FOR ALL

WARNING: DURING DISASSEMBLY, DO NOT BREATHE DUST OF THE LOOSENED BOLTS. PREVENT SKIN AND EYE CONTACT WITH RELEASED DUST. THE DUST CONTAINS NICKEL PARTICLES WHICH CAN POSE A HEALTH HAZARD. BEFORE DISASSEMBLY LUBRICATE ACCESSIBLE BOLTS AND BOLT HEADS, NUTS, AND EXPOSED THREADS WITH AN APPROVED, SUITABLE PENETRANT OIL. WEAR A FACE MASK AND GOGGLES. DO NOT REMOVE DUST DEPOSITS WITH COMPRESSED AIR. REMOVE ANY SURFACE DUST PARTICLES WITH A DISPOSABLE DAMP RAG OR SIMILAR. AFTER END OF THIS PROCEDURE, CLEAN YOUR HANDS AND EXPOSED SKIN WHERE POSSIBLE.

WARNING: MAKE SURE THAT THE BLANKING PLUG IS SUFFICIENTLY COOL BEFORE REMOVAL. THE TEMPERATURE STAYS HIGH FOR A SHORT TIME AFTER ENGINE SHUTDOWN.

CAUTION: MAKE SURE THAT THE SLEEVE FLANGED BUSHING DOES NOT FALL OUT. IF THE PART FALLS IT WILL BE DAMAGED.

(1) Wipe clean the borescope blanking plug and adjacent area with a clean Textile-Lint free Cotton - (Material No.14SBA1) .
(2) Remove the wire from the bolts.
(3) Remove the 2 bolts.
(4) Remove the blanking plug and spacer plates and keep as a set.

NOTE: If there are spacer plates, they make sure that the blanking plug has a continuous surface with the stage 3 vane outer platform. A tolerance of maximum minus 0.024 in. (0.60 mm) against the stage 3 vane surface is permitted. Thus the blanking plug must be installed with the same quantity of spacer plates as removed.

(5) Remove the sleeve flanged bushing.

Subtask 72-00-00-480-061-A ** ON A/C NOT FOR ALL

B. Put the borescope probe in position.

LP Turbine Borescope Inspection ** ON A/C NOT FOR ALL

Subtask 72-00-00-290-057-A ** ON A/C NOT FOR ALL

C. Examine the stage 3 turbine blades and shrouds

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Examine each stage 3 turbine blade and shroud in turn for:
(a) Cracks
(b) Dents
(c) Nicks
(d) Pits
(e) Tears
(f) Bends
(g) Build up of deposits
(h) Sulphidation, corrosion, blistering or coating damage
(i) Flame plate extrusion
(j) Burning or oxidation
(k) Unlatching
(l) Shingling.

Subtask 72-00-00-220-056-A ** ON A/C NOT FOR ALL

D. Cracks in all Areas

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Cracks in area A10 and A11.
(a) Accept with an inspection each 100 hours, cracks on the outer shroud if there is:
1 One single hair line crack at the leading edge of the blade, only on the coating on all blades.
(b) Accept for one ferry flight, cracks on the outer shrouds if they are:
1 Not longer than 0.080 in. (2.03 mm) but not more than 10 blades.
(c) Reject if cracks on the outer shrouds are related to:
1 Flame plate extrusion.
2 Burning and oxidation of side faces that do not touch each other.
3 Round bottomed nicks or dents.
(d) Reject if cracks are:
1 Longer than 0.080 in. (2.03 mm) in area A10.
2 Any cracks in area A11.
(2) Cracks in area A3 to A7
(a) Accept with an inspection each 100 hours, cracks if there is:
1 One single closed crack at the leading edge that extends into the airfoil not longer than 0.100 in. (2.54 mm) on one blade only.
(b) Accept for one ferry flight, cracks if there is:
1 One crack not longer than 0.125 in. (3.17 mm) on one blade only.
(c) Accept for one ferry flight, cracks if there is:
1 One crack related to tears on the trailing edge and not longer than 0.125 in. (3.17 mm) on one blade only.
(d) Reject if cracks are:
1 Related to nicks or dents.
2 Longer than 0.125 in. (3.17 mm).
3 Related to tears longer than 0.125 in. (3.17 mm).

Subtask 72-00-00-220-057-A ** ON A/C NOT FOR ALL

E. Dents, Nicks and Pits in all Areas (Area A1 to A9)

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Dents, nicks and pits in area A1.
(a) Accept round bottomed dents, nicks and pits if:
1 Not more than 0.005 in. (0.13 mm) maximum depth.
(b) Repair nicks and pits if:
1 More than (a) - VRS4606.
(c) Accept for one ferry flight if there is not more than:
1 One dent or nick per blade and not more than 0.010 in. (0.25 mm) maximum depth.
(d) Reject if dents and nicks are:
1 More than 0.010 in. (0.25 mm) maximum depth.
(2) Dents, nicks and pits in area A2.
(a) Accept round bottomed dents, nick and pits if:
1 Not more than 0.020 in. (0.5 mm) maximum depth.
(b) Reject if dents, nicks and pits are:
1 More than 0.020 in. (0.51 mm) maximum depth.
(3) Dents, nicks and pits in area A3.1.
(a) Accept round bottom dents, nicks and pits if:
1 Not more than 0.039 in. (0.99 mm) maximum depth.
(b) Reject if dents, nicks and pits are:
1 More than 0.039 in. (0.99 mm) maximum depth.
(4) Dents, nicks and pits in area A3.2 and A4.2.
(a) Accept round bottom dents if:
1 Not more than 0.010 in. (0.25 mm) maximum depth.
(b) Accept nicks and pits if:
1 Not more than 0.005 in. (0.13 mm) maximum depth.
(c) Repair dents, nicks and pits if:
1 More than (a) or (b) - VRS4606.
(d) Accept for one ferry flight, dents or nicks if:
1 Not more than 0.040 in. (1.02 mm) maximum depth.
(5) Dents, nicks and pits in area A3.3.
(a) Accept round bottom dents, nicks and pits if:
1 Not more than 0.020 in. (0.51 mm) maximum depth.
(b) Repair dents, nicks and pits if:
1 More than (a) - VRS4606.
(6) Dents, nicks and pits in area A4.1.
(a) Accept round bottom dents if:
1 Not more than 0.024 in. (0.61 mm) maximum depth.
(b) Accept nicks and pits if:
1 Not more than 0.010 in. (0.25 mm) maximum depth.
(c) Repair dents, nicks and pits if:
1 More than (a) or (b) - VRS4606.
(d) Accept for one ferry flight, dents or nicks if:
1 Not more than 0.040 in. (1.02 mm) maximum depth.
(7) Dents, nicks and pits in area A5 and A6.
(a) Accept round bottom dents, nicks and pits if:
1 Not more than 0.027 in. (0.69 mm) maximum depth, not more than 10 percent of areas A5 and A6.
(b) Repair nicks and pits if:
1 Other than (a) - VRS4606.
(c) Accept for one ferry flight, dents or nicks if:
1 Not more than 0.04010 in. (1.02 mm) maximum depth.
(8) Dents, nicks and pits in area A7.
(a) Accept round bottom dents if:
1 Not more than 0.010 in. (0.3 mm) maximum depth.
(b) Accept nicks and pits if:
1 Not more than 0.005 in. (0.13 mm) maximum depth.
(c) Repair nicks and pits if:
1 More than (b) - VRS4606.
(d) Accept for one ferry flight, dents or nicks if:
1 Not more than 0.040 in. (1.02 mm) maximum depth.
(9) Dents, nicks and pits in area A8.
(a) Accept round bottom dents with no sharp edges if:
1 Not more than 0.010 in. (0.25 mm) maximum depth.
(b) Accept nicks and pits with no sharp edges if:
1 Not more than 0.005 in. (0.13 mm) maximum depth.
(c) Accept for one ferry flight, nicks if there is:
1 One nick per blade not more than 0.010 in. (0.25 mm) maximum depth.
(d) Reject if dents and nicks are:
1 More than 0.010 in. (0.25 mm) maximum depth.
(10) Dents, nicks and pits in area A9.
(a) Accept round bottom dents if:
1 Not more than 0.024 in. (0.61 mm) maximum depth.
(b) Accept nicks and pits if:
1 Not more than 0.020 in. (0.51 mm) maximum depth.
(c) Accept for one ferry flight, dents or nicks if there is:
1 One dent or nick per blade not more than 0.040 in. (1.02 mm) maximum depth.
(d) Reject if dents and nicks are:
1 More than 0.040 in. (1.02 mm) maximum depth.

Subtask 72-00-00-220-058-A ** ON A/C NOT FOR ALL

F. Tears in Area A3 to A7:

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Accept with an inspection of the tears each 100 hours if there is:
(a) Only one tear on each blade at the trailing edge.
(b) Not more than five blades with tears.
(c) No tear is longer than 0.10 in. (2.54 mm).
(2) Accept for one ferry flight if there is:
(a) Only one tear on each blade trailing edge.
(b) Not more than ten blades with tears.
(c) No tear is longer than 0.100 in. (2.54 mm).
(3) Reject if:
(a) More than 4.F.(2)

Subtask 72-00-00-220-059-A ** ON A/C NOT FOR ALL

G. Bends in Area A3 to A7:

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Accept with an inspection each 100 hours, not more than three bends on each blade if:
(a) Distortion of each bend is not more than 0.040 in. (1.02 mm).
(b) Length of each bend is not more than 10 percent of the trailing edge length.
(2) Accept for one ferry flight if there are:
(a) Not more than ten blades with bends.
(b) Three bends, each not more than 10 percent of trailing edge length, two of which are distorted not more than 0.040 in. (1.02 mm) and the third distorted not more than 0.100 in. (2.54 mm).
(3) Reject if:
(a) More than 4.G.(2).

Subtask 72-00-00-220-060-A ** ON A/C NOT FOR ALL

H. Build up of deposits in all areas

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Accept a build up of deposits, related with usual engine running.

Subtask 72-00-00-220-061-A ** ON A/C NOT FOR ALL

I. Sulphidation, Corrosion, Blistering and Coating Damage in Area A12 and A13

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

NOTE: For damaged coating associated with crack, nick or dent refer to Para 4.D and Para 4.E.

(1) Sulphidation, corrosion, blistering and coating damage in area A12.
(a) Accept if:
1 Dark corrosion, blistering, coating loss or damage.
2 Single pits in base material or raised pustules not more than 0.079 in. (2.01 mm) in diameter or length.
(b) Reject if:
1 More than in specified in Para. 4.J.(1) (a).
(2) Sulphidation, corrosion, blistering and coating damage in area A13.
(a) Accept if:
1 Dark corrosion or blistering.
2 Areas of coating loss or damage not more than 0.059 in. (1.50 mm) in diameter or length.
3 More than specified in Para. 4.J.(2) (a) 2 in the previous step but not more than 0.118 in. (3.00 mm) in diameter or length with a minimum separation of 0.118 in. (3.00 mm).
4 Single pits in base material not more than 0.020 in. (0.51 mm) in diameter or length.
(b) Accept with an inspection each 6000 cycles if:
1 Areas of coating loss or damage more than 0.059 in. (1.50 mm) in diameter or length with a separation less than 0.118 in. (3.00 mm).
2 Areas of coating loss or damage more than 0.118 in. (3.00 mm) in diameter or length.
(c) Reject if:
1 Other than specified in Para. 4.J.(2) (a) or 4.J.(2) (b).

Subtask 72-00-00-220-063-A ** ON A/C NOT FOR ALL

J. Flame plate extrusion

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Accept flame plate extrusion from the 'Z' notch.

Subtask 72-00-00-220-087-A ** ON A/C NOT FOR ALL

K. Burning and oxidation of outer shrouds

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Accept burning and oxidation on side faces that do not touch.

Subtask 72-00-00-220-174-A ** ON A/C NOT FOR ALL

L. Visually Examine the Stage 3 Turbine Blades for Unlatching

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

NOTE: Blades are in unlatched condition if the outer shroud interlock between two blades is lost.

(1) Unlatched - Reject.

Subtask 72-00-00-220-175-A ** ON A/C NOT FOR ALL

M. Visually Examine the Stage 3 Turbine Blades for Shingling

Stage 3 Turbine Blades - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Shingled - Reject.

Subtask 72-00-00-220-171-A ** ON A/C NOT FOR ALL

N. Examine the Stage 3 Turbine Vane

Stage 3 Turbine Vane - Borescope Inspection ** ON A/C NOT FOR ALL

(1) Separated cluster bonds

NOTE: This inspection is only applicable for brazed turbine vane clusters.

NOTE: Inspection over the whole circumference (360 degree all around) is not required.

(a) Complete separation of outer shroud cluster bonds - Accept.
(b) Separation of inner shroud cluster bonds, any number, total a half of a complete braze joint for each cluster - Accept.
(c) More than in (b) - Reject.
(2) Borescope locating bushing
(a) Separation of bushing braze bond, cracked or missing material at borescope bushing, any number but all within one quadrant of bushing - Accept.
(b) Other than in (a) - Reject.

5. Close-up
Subtask 72-00-00-110-064-A ** ON A/C NOT FOR ALL

A. Cleaning:
(1) Use a clean Textile-Lint free Cotton - (Material No.14SBA1) made moist with solvent cleaner (Material No.V01-005) to clean the blanking plugs, sleeve flanged bushings and spacers.

Subtask 72-00-00-210-074-A ** ON A/C NOT FOR ALL

B. Examine the blanking plugs

LP Turbine Borescope Inspection ** ON A/C NOT FOR ALL

and
(1) Examine the blanking plug for cracks:
(a) If it is cracked, reject it.
(2) Examine the blanking plug for bends.
(a) If it is bent, reject it.
(3) Examine area D1 on the blanking plug for fretting:
(a) If the fretting is not more than 0.010 in. (0.25 mm) maximum depth, accept it.
(4) Examine the blanking plug for damage:
(a) If there is damage that does not permit the blanking plug to function correctly, reject it.

Subtask 72-00-00-210-075-A ** ON A/C NOT FOR ALL

C. Examine the sleeve flanged bushing

LP Turbine Borescope Inspection ** ON A/C NOT FOR ALL

and
(1) Examine the sleeve flanged bushing for cracks:
(a) If it is cracked, reject it.
(2) Examine area D2 on the sleeve flanged bushing for fretting:
(a) If the fretting is not more than 0.010 in. (0.25 mm) maximum depth, accept it.
(3) Examine the sleeve flanged bushing for damage:
(a) If there is damage that does not permit the sleeve flanged bushing to function correctly, reject it.

Subtask 72-00-00-410-096-A ** ON A/C NOT FOR ALL

D. Install the blanking plugs

LP Turbine Borescope Inspection ** ON A/C NOT FOR ALL

CAUTION: MAKE SURE THAT THE SLEEVE FLANGED BUSHING DOES NOT FALL OUT. IF THE PART FALLS IT WILL BE DAMAGED.

(1) Install the sleeve flanged bushing.
(2) Install the blanking plug and spacer plates.

NOTE: Use the spacer plate quantity as removed before. It makes sure that the blanking plug has a continuous surface with the stage 3 vane outer platform. A tolerance of maximum minus 0.024 in. (0.60 mm) against the stage 3 vane outer surface is permitted. Usually one spacer plate is necessary.

(3) Apply anti-seize paste (Material No.V10-129A) to the two bolts and install the bolts. Wipe off excess paste.
(4) TORQUE the bolts to between 72 and 62 lbf.in (0.81 and 0.70 m.daN )

(Ref. AMM TASK 70-23-11-911-013).
(5) Safety the bolts with corrosion resistant steel lockwire (Material No.V02-119) .

Subtask 72-00-00-410-089-A ** ON A/C NOT FOR ALL

E. Close Access
(1) Make sure that the work area is clean and clear of tools and other items.
(2) Close the thrust reverser halves (Ref. AMM TASK 78-32-00-410-010):
(a) FOR [1000EM1] (ENGINE-1)
451AL 452AR.
(b) FOR [1000EM2] (ENGINE-2)
461AL 462AR.

Subtask 72-00-00-440-067-A ** ON A/C NOT FOR ALL

F. Activate the thrust reverser HCU (Ref. AMM TASK 78-30-00-440-012).

Subtask 72-00-00-410-129-A ** ON A/C NOT FOR ALL

G. Close Access
(1) Close the fan cowls (Ref. AMM TASK 71-13-00-410-010):
(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 02:44:16 UTC