Aircraft Stair Hook with Intermediate Legs for Seal Protection
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Solution Overview
Problem
Conventional aircraft stair door retaining cables often damage the depressor bulb seals on the door frame due to chafing, which interferes with the sealing of the main entrance door during closure.
Innovation Solution
A stair support cable assembly with a first hook having a curved end portion and intermediate legs that provide additional clearance over the door seal, reducing chafing by securing to the stair hook receptacle and stair door, and featuring an elastomeric coating for further protection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional retaining cables with hooks are used to support the stair door, then the stair door can be held off the ground during aircraft repositioning, but the hooks chafe against the door seal causing damage and interfering with sealing
Solution Approach 1:
The patent introduces an intermediate structure (the elongate body with legs) that acts as a mediator between the cable hook and the door seal. This intermediate body extends the hook away from the door seal, preventing direct contact and chafing while still allowing the cable to fulfill its support function. The legs provide additional clearance and positioning to ensure the door seal remains undamaged.
2Stability of the object's composition
If the cable hook is positioned close to the door frame for secure attachment, then the stair door support is stable, but the door seal is vulnerable to chafing
Solution Approach 1:
The patent solves the spatial conflict by extending the hook structure into a third dimension - the elongate body with legs projects outward from the door frame plane, creating additional clearance in the direction perpendicular to the door seal. This dimensional extension allows the cable to be securely attached to the door frame while maintaining safe distance from the door seal.
3Ease of manufacture
If the hook structure is simplified for ease of manufacture, then production cost is reduced, but clearance and protection features are compromised
Solution Approach 1:
The patent segments the hook structure into distinct functional elements: the curved end portion for hooking, the elongate body for extension, and the legs for clearance and positioning. This segmentation allows each element to be optimized for its specific function while maintaining overall manufacturability. The segmented design provides the necessary clearance and protection features without requiring complex manufacturing processes.
Data Source
AI summary
Air stair support systems, stair support cable assemblies, and hooks are disclosed herein. A stair support system includes, but is not limited to, an aircraft fuselage, a door seal, a stair door, and a stair support cable assembly. The aircraft fuselage defines a door frame and a stair hook receptacle. The stair door has a retracted position within the door frame and an extended position that forms an entry/exit stairway. The stair support cable assembly includes a cable and two hooks. The first hook includes a curved end portion configured to hook onto the stair hook receptacle, a cable end portion secured to the cable, and an intermediate portion having first and second intermediate legs that extend the intermediate portion away from the door seal when installed on the door frame and the stair door. The second hook is configured to hook on the stair door.