Fan Casing Impact Inspection Using Trinomial Masks
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Solution Overview
Problem
Current methods for inspecting impacts on aircraft engine fan casings are inefficient, requiring complex acceptance criteria and lengthy inspection processes, leading to increased administrative burdens and delays in maintenance.
Innovation Solution
A simplified inspection method using masks and charts to quickly evaluate the harmfulness of impacts by measuring depth and length, allowing for a total harmfulness value to be determined, which reduces the number of required parameters and simplifies the inspection process for controllers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of repair
If conventional welding methods (TIG) are used to repair impacts on fan casings, then the casing can be restored, but the repair process is time-consuming and yields uns satisfactory results on aluminium casings
Solution Approach 1:
The patent applies preliminary action by pre-defining acceptance criteria (trinomials) for impact defects before inspection occurs. Controllers use these pre-established criteria to quickly determine whether defects are acceptable without requiring time-consuming repair processes. The criteria are prepared in advance based on empirical laws and reference values, enabling rapid decision-making during inspection.
2Reliability
If full casing replacement is performed for high-dimensional impacts, then structural integrity is ensured, but the process is extremely time-consuming and costly
Solution Approach 1:
The patent applies parameter changes by transforming the inspection approach from qualitative assessment to quantitative evaluation using trinomials. Each trinomial contains three parameters (maximum depth, maximum length, minimum distance between defects) that define acceptable defect limits. By measuring defect parameters against these predefined thresholds, the system determines whether impacts require replacement or are acceptable, enabling rapid decisions without full replacement for many cases.
3Adaptability or versatility
If multiple trinomial criteria are used to evaluate defects, then comprehensive coverage of defect types is achieved, but the inspection process becomes heavy and complex for controllers
Solution Approach 1:
The patent applies segmentation by dividing the inspection criteria into multiple trinomials, each targeting specific defect characteristics or locations. Instead of using a single complex evaluation system, the inspection process is segmented into discrete trinomial checks (e.g., one trinomial for depth, another for length, another for spacing). This segmentation allows controllers to systematically evaluate different defect aspects using simple, standardized criteria for each trinomial, reducing overall complexity while maintaining comprehensive coverage.
4Adaptability or versatility
If acceptance criteria are constantly updated for new defect types, then comprehensive defect coverage is achieved, but the inspection methodology becomes increasingly complex and difficult to maintain
Solution Approach 1:
The patent applies universality by designing a standardized trinomial framework that can evaluate multiple defect types using the same basic structure. Each trinomial follows a universal format with three parameters (depth, length, distance) that can be applied consistently across different defect scenarios. This universal approach allows the system to handle new defect types by simply adding new trinomial configurations rather than creating entirely new evaluation methodologies, maintaining simplicity while achieving comprehensive coverage.
Data Source
AI summary
A method for inspecting impacts present on an internal face of a fan casing, the method including: spotting a first impact present on the internal face of the fan casing; delimiting an inspection area containing the first impact; spotting the various impacts present in the delimited inspection area, the various spotted impacts forming a set of impacts to be considered; measuring, for each impact that is to be considered, the depth of length of the impact; for each impact to be considered, determining a harmfulness value, using at least one chart relating the depth and length of each impact to be considered to a level of harmfulness; determining, for the inspection area containing the first impact, a total harmfulness value by adding together the harmfulness level determined for each impact to be considered.