Composite Access Door with Chamfered Interface for Aircraft Fuel Sealing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Designing access doors for composite aircraft structures, such as CFRP laminate wing skins, that are lightweight, impact resistant, and meet regulatory specifications for fuel tightness and electrostatic performance, while avoiding material incompatibilities and weight issues associated with metal doors.
Innovation Solution
A composite access door system comprising a thin inner panel and a thicker outer panel with a chamfered interface, where the inner panel is sealed to the skin and the outer panel is sealed to the inner panel, using fasteners to clamp the door in place and create a fluid tight seal, with the outer panel designed to absorb impact loads and the inner panel capable of fracture to prevent fuel leakage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If metal access doors are used in composite aircraft skins, then impact resistance is improved, but weight increases and material incompatibilities occur
Solution Approach 1:
The access door is constructed using composite materials, specifically a laminate structure combining carbon fiber reinforced plastic (CFRP) layers with aluminum honeycomb core. This composite construction provides high impact resistance comparable to metal while significantly reducing weight, and eliminates material incompatibility issues with composite aircraft skins.
Solution Approach 2:
The door integrates multiple functional elements into a single composite structure: the CFRP face sheets provide strength and stiffness, the aluminum honeycomb core provides impact energy absorption and structural rigidity, and the integrated seal system provides fuel tight sealing. This merging of functions into a unified composite door achieves both weight reduction and maintained impact resistance.
2Strength
If metal access doors are used in composite aircraft skins, then impact resistance is improved, but material incompatibilities arise
Solution Approach 1:
The access door uses carbon fiber reinforced plastic (CFRP) laminate materials that are chemically and physically compatible with composite aircraft skins. This eliminates galvanic corrosion, thermal expansion mismatch, and other material incompatibility issues that arise when using metal doors with composite structures, while maintaining the required impact resistance through the composite laminate design.
3Weight of moving object
If the inner door panel is made thin to reduce weight, then weight is reduced, but impact resistance decreases
Solution Approach 1:
The door combines a thin inner CFRP panel with an aluminum honeycomb core structure. The thin panel reduces weight while the honeycomb core provides the necessary impact resistance and structural support. This merging of thin-walled structure with core material achieves both weight reduction and maintained strength.
Solution Approach 2:
The door uses a composite sandwich structure with CFRP face sheets and aluminum honeycomb core. This composite construction allows the face sheets to be thin (reducing weight) while the core material provides the necessary impact resistance and structural integrity, achieving both goals simultaneously.
4Reliability
If multiple fasteners are used to secure the door, then reliability is improved, but device complexity increases
Solution Approach 1:
The door employs a segmented sealing approach with multiple seals positioned at different locations (inner seal between inner panel and skin, outer seal between inner and outer panels). This segmentation of the sealing function into multiple distributed seals provides reliable fuel tight sealing without requiring a high density of fasteners, reducing overall device complexity.
Data Source
AI summary
A method of installing a door in an access opening in a skin of an aircraft. A composite inner door panel is positioned against an inside face of the skin. A composite outer door panel is positioned against an outside face of the skin. A plurality of fasteners is installed through fastener openings in the composite outer door panel. The plurality of fasteners is tightened to form a chamfered interface between the skin and the composite outer door panel.