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 con fi dence. 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, modi fi cations, spare parts, designs, or con fi guration 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 20ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT Stator Shrouds P/N 1847M52P14

1. P LA N N I N G I N F O R M A T I O N A. E f fe ct i v i ty 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. D e s c r i p t i o n This Service Bulletin provides on-wing borescope inspection (BSI) procedures for the stage 1 HPT stator shrouds P/N 1847M52P14. C. C o m p l i a n ce 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. N O T E 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. N O T E 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. N O T E 3 : Compliance with GE90 S/B 72-0937 is a terminating action for this Service Bulletin. N O T E 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 fl eet.

November 19, 2012 GE90 S/B 72-1076 PAGE 2 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT Stator Shrouds P/N 1847M52P14

D. C o n c u r re n t Re q u i re m e n ts None. E. R e a s o n (1) Objective: To improve reliability and reduce signi fi cant 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 fl eet experience and analysis. F. A p p ro va l This Service Bulletin contains no modi fi cation information that revises the approved con fi guration and therefore does not require FAA approval. G. M a n p owe r 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. We i g h t a n d B a l a n ce Weight and balance are not changed. I. R efe re n ce s (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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT Stator Shrouds P/N 1847M52P14

J. P u b l i ca t i o n s Af fe cte d GE90 Boeing 777 Aircraft Maintenance Manual (AMM) K. I n te rc h a n g e a b i l i ty Not applicable. L. S of twa re Acco m p l i s h m e n t S u m m a ry Not applicable. 2. M A T E R I A L I N F O R M A T I O N A. M a te r i a l

- P r i ce a n d A va i l a b i l i ty (1) Parts necessary to do this Service Bulletin: None. (2) Other Spare Parts: None. (3) Consumables: None. B. I n d u s t ry S u p p o rt I n f o r m a t i o n Contact your Customer Support Manager (CSM). C. C o n fi g u ra t i o n C h a rt Not applicable. D. P a rts D i s p o s i t i o n None. E. T o o l i n g - P r i ce a n d Ava i l a b i l i ty T

o o l N u m b e r D e s c r i p t i o n

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

-- Flexible Borescope ( fl exscope) 6 mm or 8 mm diameter minimum of 3.5 meters in length (recommended equipment)
N O T E : A fl exscope shorter than 3.5 meters cannot be used to accomplish this inspection.

November 19, 2012 GE90 S/B 72-1076 PAGE 4 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT Stator Shrouds P/N 1847M52P14

3. A C C O M P L I S H M E N T I N S T R U C T I O N S A. S ta g e 1 H P T S ta to r S h ro u d B S I w i t h a 3

. 5

- M e te r o r L o n g e r F l exs co p e N O T E 1 : Video BSI or photos are strongly recommended when this inspection is done. N O T E 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. W

A R N I N G : USE THERMAL GLOVES WHEN YOU MOVE OR TOUCH HOT OR COLD PARTS. HOT OR COLD PARTS CAN CAUSE INJURY. CA U T I O N : 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: N O T E 3 : A fl exscope 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 fl exscope into the borescope port of the combustor diffuser nozzle (CDN) and pass it into the fl ow path. (c) Follow the direction of the stage 1 HPT nozzle and continue to insert the fl exscope over the top of the engine. Continue to feed the fl exscope into the fl ow path until you can see the fl exscope insertion point ( fl exscope entering through the borescope port). N O T E : It is very important that you can see the borescope entry point to make sure that a full 360 degrees fl exscope travel has been accomplished for the inspection. (d) Carefully remove the fl exscope. Make sure to examine the stage 1 HPT stator shrouds as you remove the fl exscope. 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 speci fi ed in paragraph 3.B., I n s p e ct i o n Re s u l ts E va l u a t i o n , and complete the Inspection Findings Report Form as speci fi ed in paragraph 3.C., I n s p e ct i o n F i n d i n g s R e p o rt i n g , and Figure 3. November 19, 2012 GE90 S/B 72-1076 PAGE 5 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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: N O T E : A fl exscope 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 fl exscope into the borescope port of the HPT case and pass it into the fl ow path. (c) Follow the direction of the stage 2 HPT nozzle and continue to insert the fl exscope under the bottom of the engine. Continue to feed the fl exscope into the fl ow path until you can see the fl exscope insertion point (fl exscope entering through the borescope port). N O T E : It is very important that you can see the borescope entry point to make sure that a full 360 degrees fl exscope travel has been accomplished for the inspection. (d) Carefully remove the fl exscope. Make sure to examine the stage 1 HPT stator shrouds as you remove the fl exscope. 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 speci fi ed in paragraph 3.B., I n s p e ct i o n Re s u l ts E va l u a t i o n , and complete the Inspection Findings Report Form as speci fi ed in paragraph 3.C., I n s p e ct i o n F i n d i n g s R e p o rt i n g , 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. I n s p e ct i o n Re s u l ts E va l u a t i o n (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: N O T E : 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.ENGINE - HPT Stage 2 Nozzle (72-52-00) - On-Wing Borescope Inspection of Stage 1 HPT Stator Shrouds P/N 1847M52P14

N O T E : If you can see the stage 1 hanger internal baf fl e, 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. N O T E : If you can see the stage 1 hanger internal baf fl e, 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 fl ow 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. I n s p e ct i o n F i n d i n g s Re p o rt i n g (1) Report the inspection fi ndings 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 PAGE 7 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PAGE 8 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PAGE 18 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PAGE 19 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst 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 PAGE 20 GE PROPR IETARY INFORMATION - Subject to the restrictions on the cover or fi rst page.