Expandable Boroscope Guide Fixture for Gas Turbine Cavity Inspection

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Solution Overview

Problem

Current inspection tools for gas turbine engines face challenges in providing effective tool guidance and support, particularly for inspecting second stage disks in high-pressure turbines, leading to issues like high engine removals due to powder metal defects and the need for quick tool changeovers.

Innovation Solution

A boroscope guide fixture with expandable components and elastic constraints is used to securely fit into gas turbine engine cavities, allowing for inspection through expandable segments that are locked into place using threading or compression, ensuring precise tool positioning and stability during inspections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If inspection tools are used for gas turbine engine cavities, then inspection capability is provided, but tool location errors occur and tool stability is insufficient

Engineering Contradiction:
Improveinspection precisionVSAvoidtool stability
Core Design Contradiction:
Measurement precisionVSReliability

Solution Approach 1:

The inspection tool employs an expandable fixture system that transitions from a compact transport state to an expanded inspection state. The fixture includes expandable components with elastomeric elements that can be compressed and expanded to engage with the engine cavity, providing dynamic adaptation to different cavity geometries while maintaining stable positioning during inspection

Inventive Principle:
Principle #15Dynamics

Solution Approach 2:

The fixture is divided into multiple modular sections including first and second sections with respective expandable components, allowing independent adjustment and positioning of each segment. This segmentation enables the tool to adapt to varying cavity shapes while maintaining overall structural stability and precise inspection positioning

Inventive Principle:
Principle #1Segmentation

2Productivity

If traditional inspection tools are used, then inspection function is provided, but tool changeover time is excessive

Engineering Contradiction:
Improveinspection efficiencyVSAvoidtool changeover time
Core Design Contradiction:
ProductivityVSLoss of time

Solution Approach 1:

The fixture design incorporates universal engagement features with tapered surfaces and standardized mounting interfaces that can accommodate different engine cavity types. The expandable components with elastomeric elements provide adaptable engagement across various geometries, allowing a single tool design to serve multiple inspection applications without requiring frequent tool changes

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The fixture sections are designed to nest within each other during transport and storage, with the third section movable relative to the first and second sections. This nested configuration reduces tool size for storage while enabling rapid deployment and changeover by simply extending the nested sections into their operational positions

Inventive Principle:
Principle #7Nested doll (Nesting)

3Reliability

If expandable components are used to secure the tool, then tool guidance is improved, but device complexity increases

Engineering Contradiction:
Improvetool guidanceVSAvoidfixture complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The expandable components utilize elastomeric elements that change their physical parameters (compression and expansion) to achieve engagement with the engine cavity. By changing the compression state of these elastomeric elements, the fixture transitions between retracted and expanded configurations, providing reliable tool guidance without complex mechanical actuation systems

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The fixture employs dynamic expandable components that can transition between compact and expanded states during operation. The third section is movable relative to the first and second sections, allowing the tool to adapt its configuration dynamically during insertion and positioning while maintaining relatively simple structural design

Inventive Principle:
Principle #15Dynamics

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The boroscope guide fixture provides reliable tool guidance and support, reducing engine removals due to defects and enabling efficient inspections by preventing tool location errors and allowing for quick changeovers.

Implementation Method 1

first elastics constraining the first expandable components and configured to constrain the first expandable components in a retracted condition

Methodology Applied
Scientific EffectElasticity: Elasticity

Implementation Method 2

The boroscope is operable to draw the third sections toward the second sections whereupon registration of the second convex and concave ends expands the second expandable components against the second elastics

Methodology Applied
Scientific EffectCompression: Compression

Data Source

PatentEP4610638A1Boroscope guide fixture
Publication Date: 2025.09.03 RTX CORP
  • EP4610638A1 patent drawingFigure 1
  • EP4610638A1 patent drawingFigure 2~3
  • EP4610638A1 patent drawingFigure 4~5

AI summary

A boroscope guide fixture (201) is provided and includes a boroscope (210), a first section (220) disposed about the boroscope (210) and including first expandable components (221), first elastics (222) constraining the first expandable components (221) and first concave ends, second sections (230) disposed about the boroscope (210) and third sections (250). The second sections (230) respectively include second expandable components (231), second elastics (232) constraining the second expandable components (231), first convex ends to register with the first concave ends and second concave ends. The third sections (250) are movably affixed to the boroscope (210) and respectively include second convex ends to register with the second concave ends. The boroscope (210) is operable to draw the third sections (250) toward the second sections (230) whereupon registration of the second convex and concave ends expands the second expandable components (231) against the second elastics (232) and registration of the first convex and concave ends expands the first expandable components (221) against the first elastics (222).