ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

GE PROPRIETARY INFORMATION

The information contained in this document is GE proprietary information and is disclosed in

confidence. It is the property of GE and shall not be used, disclosed to others or reproduced

without the express written consent of GE, including, but without limitation, it is not to be used

in the creation, manufacture, development, or derivation of any repairs, modifications, spare

parts, designs, or configuration changes or to obtain FAA or any other government or regulatory approvalto do so. If consentis givenfor reproduction inwhole or inpart,this notice andthe

notice set forth on each page of this document shall appear in any such reproduction in whole

or in part.

This technical data is considered EAR controlled pursuant to 15 CFR Parts 730-774 respectively. Transfer of this data by any means to a Non-US Person, whether in the United States

or abroad,withouttheproperU.S.Government authorization (e.g., License, exemption,NLR,

etc.), is strictly prohibited.

Copyright (2012) GeneralElectric Company, U.S.A.

November 19, 2012 GE90 S/B 72-1076

PAGE 1 of 20
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

1. PLANNING INFORMATION

A. Effectivity

GE90-76B, -85B, -90B, -94B

This Service Bulletin is applicable to these GE90 engines:

. GE90 engines, serial numbers 900-510 and up.

These serial numbers are the best available data.

This Service Bulletin is applicable to all GE90 engines that had the stage 1 high

pressure turbine (HPT) stator shrouds P/N 1847M52P14 installed either from

production or during shop visit.

B. Description

This Service Bulletin provides on-wing borescope inspection (BSI) procedures for

the stage 1 HPT stator shrouds P/N 1847M52P14.

C. Compliance

Category 2

GE recommends this inspection be performed at a 2,000 cycles since new (CSN)

threshold for production engines and 2,000 cycles since installation (CSI) on

engines that had the stage 1 HPT stator shrouds P/N 1847M52P14 installed during

a shop visit.

GE also recommends this inspection be repeated at 250 cycle intervals thereafter.

NOTE 1: For engines that have accumulated more than 2,000 cycles on the stage 1

HPT stator shroud P/N 1847M52P14 at the time of initial publication of this

Service Bulletin, GE recommends the affected engine be inspected within

two months of the initial publication date of this Service Bulletin.

NOTE 2: For engines that have less than 2,000 cycles on the stage 1 HPT stator

shroud P/N 1847M52P14 at the time of initial publication of this Service

Bulletin, GE recommends the affected engine be inspected within two

months of reaching 2,000 cycles on the stage 1 HPT stator shrouds.

NOTE 3: Compliance with GE90 S/B 72-0937 is a terminating action for this Service

Bulletin.

NOTE 4: This Service Bulletin can be accomplished on wing or in shop.

This Service Bulletin is offered to improve the reliability or performance of your GE

product, or to help prevent the occurrence of the event or condition described in this

Service Bulletin. If the operator elects not to participate in the bulletin, that decision

will be taken into consideration by GE in evaluating future product performance

issues that may arise in the operator’s fleet.

November 19, 2012 GE90 S/B 72-1076

PAGE 2

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

D. Concurrent Requirements

None.

E. Reason

(1) Objective:

To improve reliability and reduce significant events.

(2) Condition:

The stage 1 HPT stator shrouds show an accelerated deterioration that can

result in an unserviceable condition.

(3) Cause:

The cause for the accelerated distress is currently under investigation.

(4) Inspection:

Inspect the stage 1 HPT stator shrouds for corrosion/oxidation and missing

material/holes.

(5) Substantiation:

Substantiation is by fleet experience and analysis.

F. Approval

This Service Bulletin contains no modification information that revises the approved

configuration and therefore does not require FAA approval.

G. Manpower

After you get access to the borescope port of the stage 1 HPT stator shrouds, you

will need approximately 4 man-hours to do the inspection portion of this Service

Bulletin.

H. Weight and Balance

Weight and balance are not changed.

I. References (Use the latest version of these documents)

GE90 Boeing 777 Aircraft Maintenance Manual (AMM)

GEK 100701-1, GE90 Illustrated Parts Catalog (IPC)

GE90 S/B 72-0937, ENGINE - Stage 2 HPT Nozzle Assembly (72-52-00) - HPT

Stage 1 Shrouds and Shroud HPT Stage 1 Hangers - New and Rework

November 19, 2012 GE90 S/B 72-1076

PAGE 3

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

J. Publications Affected

GE90 Boeing 777 Aircraft Maintenance Manual (AMM)

K. Interchangeability

Not applicable.

L. Software Accomplishment Summary

Not applicable.

2. MATERIAL INFORMATION

A. Material - Price and Availability

(1) Parts necessary to do this Service Bulletin:

None.

(2) Other Spare Parts:

None.

(3) Consumables:

None.

B. Industry Support Information

Contact your Customer Support Manager (CSM).

C. Configuration Chart

Not applicable.

D. Parts Disposition

None.

E. Tooling - Price and Availability

Tool Number Description

-- Torque Wrench capable of up to 220 lb in. (25 N·m)

-- Flexible Borescope (flexscope) 6 mm or 8 mm diameter

minimum of 3.5 meters in length (recommended equipment)

NOTE: A flexscope shorter than 3.5 meters cannot be used to accomplish

this inspection.

November 19, 2012 GE90 S/B 72-1076

PAGE 4

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

3. ACCOMPLISHMENT INSTRUCTIONS

A. Stage 1 HPT Stator Shroud BSI with a 3.5-Meter or Longer Flexscope

NOTE 1: Video BSI or photos are strongly recommended when this inspection

is done.

NOTE 2: Stage 1 HPT stator shroud damage has been seen at all clock

positions. Damage occurs more at mid chord and aft on stage 1 HPT

stator shroud surface. Inspection of the entire stage 1 HPT stator

shroud surface is required. You must look between the blades and

under the blade tips to make sure that no indications are missed.

WARNING: USE THERMAL GLOVES WHEN YOU MOVE OR TOUCH HOT OR

COLD PARTS. HOT OR COLD PARTS CAN CAUSE INJURY.

CAUTION: MAKE SURE THE TEMPERATURE OF THE ENGINE AND THE

ADJACENT AREAS NEAR THE BSI PORTS ARE LESS THAN 150

F (66 C) DEGREES. DO NOT DO A BSI IF THE ADJACENT AREAS

ARE TOO HOT TO TOUCH. DO THE BSI WHEN THE ENGINE

TEMPERATURE IS LESS THAN 150 F (66 C) DEGREES. THIS WILL

PREVENT DAMAGE TO THE BORESCOPE EQUIPMENT.

(1) Do a 360-degree BSI of the stage 1 HPT stator shroud (1, Figure 1) leading

edge (LE) and mid chord. Refer to the GE90 Boeing 777 AMM, TASK

72-00-00-290-817-G00, SUBTASK 72-00-00-290-047-G00, and do as follows:

NOTE 3: A flexscope less than 3.5 meters in length cannot be used to do the

BSI of the stage 1 HPT stator shrouds.

(a) Remove the borescope plug at the "Q" location.

(b) Insert a flexscope into the borescope port of the combustor diffuser

nozzle (CDN) and pass it into the flow path.

(c) Follow the direction of the stage 1 HPT nozzle and continue to insert the

flexscope over the top of the engine. Continue to feed the flexscope into

the flow path until you can see the flexscope insertion point (flexscope

entering through the borescope port).

NOTE: It is very important that you can see the borescope entry point

to make sure that a full 360 degrees flexscope travel has been

accomplished for the inspection.

(d) Carefully remove the flexscope. Make sure to examine the stage 1 HPT

stator shrouds as you remove the flexscope. Inspect the mid chord of

the stage 1 HPT stator shrouds (area of the stage 1 HPT stator shrouds

between the blades) and the LE of the stage 1 HPT stator shrouds.

(e) While you examine the stage 1 HPT stator shrouds, evaluate each stage

1 HPT stator shroud as specified in paragraph 3.B., Inspection Results

Evaluation, and complete the Inspection Findings Report Form as

specified in paragraph 3.C., Inspection Findings Reporting, and Figure 3.

November 19, 2012 GE90 S/B 72-1076

PAGE 5

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

(f) When you complete the inspection, install the borescope plug. Refer to

the GE90 Boeing 777 AMM, SUBTASK 72-00-00-410-046-G00.

(2) Do a 360-degree BSI of the stage 1 HPT stator shroud (1, Figure 1) trailing

edge (TE) and mid chord as follows:

NOTE: A flexscope less than 3.5 meters in length cannot be used to do the

BSI of the stage 1 HPT stator shrouds.

(a) Remove the borescope plug at the "R" location.

(b) Insert a flexscope into the borescope port of the HPT case and pass

it into the flow path.

(c) Follow the direction of the stage 2 HPT nozzle and continue to insert

the flexscope under the bottom of the engine. Continue to feed the

flexscope into the flow path until you can see the flexscope insertion

point (flexscope entering through the borescope port).

NOTE: It is very important that you can see the borescope entry point

to make sure that a full 360 degrees flexscope travel has been

accomplished for the inspection.

(d) Carefully remove the flexscope. Make sure to examine the stage 1 HPT

stator shrouds as you remove the flexscope. Inspect the mid chord of

the stage 1 HPT stator shrouds (area of the stage 1 HPT stator shrouds

between the blades) and the TE of the stage 1 HPT stator shrouds.

(e) While you examine the stage 1 HPT stator shrouds, evaluate each stage

1 HPT stator shroud as specified in paragraph 3.B., Inspection Results

Evaluation, and complete the Inspection Findings Report Form as

specified in paragraph 3.C., Inspection Findings Reporting, and Figure 4.

(f) When you complete the inspection, install the borescope plug. Refer to

the GE90 Boeing 777 AMM, SUBTASK 72-00-00-410-046-G00.

B. Inspection Results Evaluation

(1) Use the shroud serviceability limits published in the GE90 Boeing 777 AMM,

TASK 72-00-00-290-817-G00, SUBTASK 72-00-00-290-047-G00, except

for the following:

NOTE: Refer to Figure 2 for examples of the stage 1 HPT stator shrouds

thermal distress.

(a) Holes within 0.35 inch (8.9 mm) of the LE are serviceable on a reduced

inspection interval of every 50 cycles.

(b) Holes beyond 0.35 inch (8.9 mm) of the LE less than 0.15 inch (3.8 mm)

in diameter [maximum area of 0.018 sq in. (0.12 sq cm)] are serviceable

on a reduced inspection interval of every 25 cycles if the LE of the

shroud is present forward of the hole.

November 19, 2012 GE90 S/B 72-1076

PAGE 6

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

NOTE: If you can see the stage 1 hanger internal baffle, the damage is

more than 0.35 inch (8.9 mm) from the LE and must be evaluated

in accordance with the serviceability requirements listed above

in this Service Bulletin.

(c) Holes beyond 0.35 inch (8.9 mm) of the LE between 0.15 inch (3.8 mm)

in diameter [maximum area of 0.018 sq in. (0.12 sq cm)] and 0.25 inch

(6.4 mm) in diameter [maximum area of 0.049 sq in. (0.32 sq cm)] are

serviceable on a reduced inspection interval of every 10 cycles if the LE

of the shroud is present forward of the hole.

NOTE: If you can see the stage 1 hanger internal baffle, the damage is

more than 0.35 inch (8.9 mm) from the LE and must be evaluated

in accordance with the serviceability requirements listed above

in this Service Bulletin.

(d) Lifting of the shroud split line, LE or TE is acceptable if the area of the

lifting material meets the requirements in the GE90 Boeing 777 AMM,

SUBTASK 72-00-00-290-047-G00, for missing material.

(e) Black oxide/corrosion build up around the shroud cooling holes on

shroud flow path surface is acceptable for repeat inspection interval

of every 250 cycles.

(f) Black oxide/corrosion build up on shroud surface that blocks cooling

holes is acceptable for repeat inspection interval of every 100 cycles.

C. Inspection Findings Reporting

(1) Report the inspection findings to GE Group Field Service/PSE Representative.

Fill out the Inspection Findings Report Form. Refer to Figure 3 and Figure 4.

(2) Video borescope/photograph the inspection of the stage 1 HPT stator

shrouds. Retain the inspection records for one year (12 months).

(3) Send the completed Inspection Findings Report Form and pictures to:

kyle.blomgren@ge.com

November 19, 2012 GE90 S/B 72-1076

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GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Location of the Stage 1 HPT Stator Shroud

Figure 1, ( Sheet 1 of 3 )

November 19, 2012 GE90 S/B 72-1076

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GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Location of the Stage 1 HPT Stator Shroud

Figure 1, ( Sheet 2 )

November 19, 2012 GE90 S/B 72-1076

PAGE 9

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Location of the Stage 1 HPT Stator Shroud

Figure 1, ( Sheet 3 )

November 19, 2012 GE90 S/B 72-1076

PAGE 10

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 1 of 8 )

November 19, 2012 GE90 S/B 72-1076

PAGE 11

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 2 )

November 19, 2012 GE90 S/B 72-1076

PAGE 12

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 3 )

November 19, 2012 GE90 S/B 72-1076

PAGE 13

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 4 )

November 19, 2012 GE90 S/B 72-1076

PAGE 14

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 5 )

November 19, 2012 GE90 S/B 72-1076

PAGE 15

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 6 )

November 19, 2012 GE90 S/B 72-1076

PAGE 16

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 7 )

November 19, 2012 GE90 S/B 72-1076

PAGE 17

GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Stage 1 HPT Stator Shrouds - Thermal Distress

Figure 2, ( Sheet 8 )

November 19, 2012 GE90 S/B 72-1076

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GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Inspection Findings Report Form - LE

Figure 3

November 19, 2012 GE90 S/B 72-1076

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GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.
ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT

Stator Shrouds P/N 1847M52P14

Inspection Findings Report Form - TE

Figure 4

November 19, 2012 GE90 S/B 72-1076

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GE PROPRIETARY INFORMATION - Subject to the restrictions on the cover or first page.