CFM56 HPC: Borescope Inspection Guide

April 2016

Book Number: GEK 119347

CFM, CFM56, LEAP and the CFM logo are trademarks of CFM International, a 50/50 joint company between Snecma (Safran group) and GE. The information in this document is CFM Proprietary Information and is disclosed in confidence. It is the property of CFM International and its parent companies, and shall not be used, disclosed to others or reproduced without the express written consent of CFM. If consent is given for reproduction in whole or in part, this notice shall appear in any such reproduction in whole or in part. The information contained in this document may also be controlled by the U.S. and French export control laws. Unauthorized export or re-export is prohibited.

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This guide is designed to aid Airline Maintenance Personnel with the identification of typical visual findings during a CFM56 High-Pressure Compressor (HPC) Module borescope inspection. Engine model specific limitations and detailed acceptance and non-acceptance criteria are only found in the Engine Manuals and/or Aircraft Maintenance Manuals

Contact CFM if further assistance is needed in classification of HPC borescope inspection findings.

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CFM International Proprietary Information

The information contained in this document is CFM international proprietary information and disclosed in confidence. CFM International is a 50/50 joint company between Snecma and General Electric Company. It is the property of CFM International and shall not be used disclosed to others or reproduced without the express written consent of CFM International, 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 regulatory approval to do so. If consent is given for reproduction in whole or in part, this notice and the notice set forth on each page of this document shall appear in any such reproduction in whole or in part. The information contained in this document may also be controlled by the U.S. and French export control laws. Unauthorized export or re-export is prohibited.

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Introduction

This guide is intended exclusively for the owners and operators of CFM engines. It has been prepared as a guide for use in the analysis of borescope findings on CFM HPC components. The purpose of the guide is to enable identification of the typical visual findings during the borescope inspection.

The data and images presented here do not supersede or replace any of the engine or aircraft manufacturer’s Instructions for Continued Airworthiness. This document and the material within it are subordinate to the Aircraft Maintenance Manual and Engine Manual.

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Applicability

Inspection Repair-3 72-00-00-216-049 72-00-00-308-015

-5A 72-31-00-290-001 72-31-00-300-003

-5B 72-31-00-290-002 72-31-00-300-003

-5C 72-31-00-290-801 72-31-00-300-802

-7B 72-00-00-200-804 72-00-00-300-801

EngineModel

AMM

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CFM56 HPC BSI Guide

General Guidelines :

1. Determine damage location

2. Characterize the type of damage

3. Measure damage dimension

4. Find applicable limit

5. Determine Serviceability

6. Assess Over-Serviceable and Repair limits

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CFM56 HPC BSI Guide 1. Determine the Location

HPC blade Regions

Reference Dimensions

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CFM56 HPC BSI Guide 1. Determine the location – Multiple Regions

For damage in multiple regions, apply the allowance to the damage that is located in each region.

Dent Overlaps Root Radius and 25% of L

Within Root Radius

Within 25% of L

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CFM56 HPC BSI Guide 2. Types of Damage

Typical Damage

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Crack: A parting or discontinuity in the parent material Tear: A physical separation, pulling apart, or wrenching of metal which can be

caused by impact damage. Dent: A completely smooth surface depression caused by pressure or impact

from a smooth, rounded foreign object. The parent material is displaced, but none is separated.

Nick: A surface impression with sharp corners or bottom, usually caused by

pressure or impact from a sharp-edged object. The parent material is displaced, but usually none is separated.

Pit: A minute depression or cavity having no sharp, high-stress corners in the

surface of the material. Pits are usually caused by chemical reaction (rusting, chemical corrosion).

High metal: Displaced metal adjacent to a defect such as a scratch, nick or gouge, which

is raised above the surrounding.

CFM56 HPC BSI Guide 2. Types of Damage - Definitions

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CFM56 HPC BSI Guide 3. Depth Measurement

Reference points influence measurement

0.013 inch 0.005 inch

• Reference points should be close to the damage to avoid the influence of surface curvature

Same blade different measurements

Actual measurement=0.0049 inch

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CFM56 HPC BSI Guide 3. Radial Tip Crack Measurement

1. Determine Distance from Leading/Trailing Edge 2. Determine Radial Crack length

3. Compare to AMM for serviceability

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CFM56 HPC BSI Guide 3. Measurement: Missing Tip Corner

Missing Material measured by extending edges to make a corner

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CFM56 HPC BSI Guide 3. Measurement: Axis of Damage

• Atypical dim B damage (does not involve edge)

• Defect depth should be measured in the axis of damage (into the metal), as indicated in AMM note:

“Defect Depth is in axis of damage unless otherwise noted. “

• Typical dim B damage impacts edge • Defect depth measurement is the

distance from the edge, as indicated in AMM figure.

Measurement establishes location

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CFM56 HPC BSI Guide 6. Over-Serviceable and Repair Limits

Be aware of extended limits available via:

• 10 cycle/25 hour Service Extension

• Blend repair

Note: Dim B blends require a one-time follow-up Inspection (25 to 100 cycles)

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