Frusto-Conical Fittings for Aircraft APU Support
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Solution Overview
Problem
Conventional support systems for auxiliary power units in aircraft are complex, costly, and difficult to maintain due to their size and complexity, which complicates inspection, maintenance, and repair, while also failing to adequately address high temperature and fire resistance requirements.
Innovation Solution
A simplified support system using frusto-conical fittings made of high thermal and mechanical strength materials like titanium or steel, which are lightweight and cost-effective, providing secure attachment and securing points with minimal components, allowing for efficient manufacturing and easier access for maintenance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a complex framework of bars is used to support the auxiliary power unit, then adequate securing and mechanical strength are achieved, but the system complexity and manufacturing cost increase significantly
Solution Approach 1:
The complex framework of bars is segmented into individual frusto-conical fittings, each performing a specific support function. This segmentation allows for simplified manufacturing of individual components while maintaining the overall structural integrity and load-bearing capacity of the support system.
Solution Approach 2:
Multiple functional elements of the support system are merged into a single integrated frusto-conical fitting structure. The fitting combines attachment means, load-bearing capability, and thermal resistance properties in one component, eliminating the need for separate bars and connectors while achieving equivalent or superior mechanical strength.
2Reliability
If a complex framework of bars is used for support, then adequate securing is achieved, but the manufacturing and assembly cost increases
Solution Approach 1:
The support system is divided into standardized frusto-conical fittings that can be manufactured independently using conventional machining processes. This segmentation enables parallel production of multiple identical components, reducing manufacturing complexity and cost while ensuring consistent quality and reliable securing capability.
Solution Approach 2:
The frusto-conical geometry parameters are optimized to provide adequate securing capability with minimal material usage. The specific cone angle, wall thickness, and height parameters are designed to achieve the required mechanical strength and thermal resistance while minimizing manufacturing complexity and cost compared to complex bar frameworks.
3Strength
If a complex framework structure is used, then support strength is adequate, but access for inspection and maintenance becomes difficult
Solution Approach 1:
The support system is segmented into discrete frusto-conical fittings that are spatially distributed around the auxiliary power unit. This segmentation creates open spaces and clear access paths for inspection and maintenance activities, while each individual fitting maintains its load-bearing function to ensure adequate support strength.
Solution Approach 2:
Instead of using a dense framework that encloses the auxiliary power unit, the support system uses sparsely distributed frusto-conical fittings that provide support from the outside. This inverted approach maintains structural integrity while maximizing accessibility for inspection and maintenance operations.
4Strength
If conventional bar frameworks are used, then support requirements are met, but repair costs increase when deterioration occurs
Solution Approach 1:
The support system is divided into independent frusto-conical fittings that can be replaced individually without affecting the entire support structure. This segmentation reduces repair costs by allowing replacement of only the deteriorated components rather than the entire framework, while maintaining adequate support capability through the remaining functional fittings.
Solution Approach 2:
The frusto-conical fittings are designed as replaceable components that can be discarded when deteriorated and replaced with new or refurbished units. This approach reduces repair costs compared to reconstructing entire bar frameworks, while the modular design ensures that support capability is quickly restored with minimal disruption to the auxiliary power unit operation.
Data Source
AI summary
Support system suitable for sustaining an auxiliary power unit of an aircraft to a fixed structure (2) belonging to a compartment of the auxiliary power unit (6) of the aircraft. The support system is made in a high mechanical strength material and with high resistance to ignition, and comprises three fittings (3, 4, 5) two of which are frusto-conical and one with a substantially cylindrical. Fittings (3, 4, 5) being able to be hollow and being able to comprise an array of lateral ribs. Each one of them presenting a first end (7) comprising means of attachment of the support system (8) to the fixed structure (2) and a second end (9) comprising means of securing of the support system (8) which are joined to the auxiliary power unit (1) in the periphery of the extension of said auxiliary power unit (1).