Aircraft Wing Blind Fastener Assembly With Spark Containment Cap
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Solution Overview
Problem
Existing aircraft wing assembly methods requiring single-sided installation of blind fasteners face challenges in accurately positioning spark containment caps and increase production time due to additional cleaning and de-burring steps.
Innovation Solution
A method involving forming a locating through hole in the structural element, attaching a spark containment cap, positioning the wing skin, and forming a larger fastening through hole to accurately install a blind fastener covered by the cap, reducing the need for subsequent cleaning and de-burring steps.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If single-sided assembly with blind fasteners is used, then access to inside of wing structure is prevented and assembly can be performed from outside, but accurate positioning of spark containment cap and through hole becomes essential and production time increases
Solution Approach 1:
The spark containment cap is attached to the structural element before drilling the through hole. This preliminary action ensures the cap is in its final position, and subsequent drilling automatically positions the hole correctly relative to the cap, eliminating alignment issues that would occur if the cap were positioned after drilling.
Solution Approach 2:
The assembly process is segmented into distinct sequential steps: first attaching the spark containment cap to the structural element, then drilling the through hole, and finally inserting the blind fastener. This segmentation allows each step to be optimized independently, with the cap attachment establishing a reference framework for subsequent operations.
2Manufacturing precision
If wing skin is removed after drilling to clean up swarf or de-burr, then manufacturing quality improves, but production time increases
Solution Approach 1:
The wing skin is temporarily removed only during the drilling operation to access the inside of the structural element for swarf removal and de-burring. After these critical cleaning operations are completed, the wing skin is reattached and fastened. This extracts the skin removal action to only when absolutely necessary, minimizing the time the skin is off and reducing overall production time while still achieving quality hole preparation.
3Reliability
If spark containment cap is applied before drilling, then lightning strike protection and fuel tightness are ensured, but accurate positioning of cap and through hole becomes critical
Solution Approach 1:
The spark containment cap is attached to the structural element before drilling the through hole. This preliminary action ensures the cap is in its final position, and subsequent drilling automatically positions the hole correctly relative to the cap, eliminating alignment issues that would occur if the cap were positioned after drilling.
4Productivity
If blind fasteners are used for single-sided assembly, then installation can be performed from one side without subsequent steps, but additional sealing with spark containment caps is required
Solution Approach 1:
The spark containment cap serves multiple functions simultaneously: it provides lightning strike protection, ensures fuel tightness, and acts as a positioning reference for the through hole. By merging these functions into a single component attached in advance, the design avoids adding separate sealing elements while maintaining safety and assembly efficiency.
Data Source
AI summary
A method of joining a wing skin to a structural element of an aircraft wing. A locating through hole is formed in the structural element, extending along a path between a first side of the structural element and a second side of the structural element. A spark containment cap is attached to the first side of the structural element to covering an opening of the locating through hole. A portion of the wing skin is positioned on the second side of the structural element. A fastening through hole having a larger diameter than the locating through hole is formed through both the wing skin and the structural element and along the path of the locating through hole. A fastener is inserted into the fastening through hole and the structural element secured to the wing skin, an end of the fastener being covered by the spark containment cap.