Aircraft Plug Door Structure for In-Plane Load Transfer

Solution Overview

Problem

Existing aircraft door designs, particularly canopy doors, require extensive structural reinforcement and additional framing to manage in-plane stresses caused by pressurization, which increases weight, cost, and complexity, especially during aircraft conversions from passenger to cargo service.

Innovation Solution

The development of a plug door assembly with engagement assemblies that transfer in-plane stress between the door and the fuselage, eliminating the need for extra structural framing around the opening, and allowing the door to function as an integral part of the fuselage in terms of stress management.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If extensive structural reinforcement and additional framing are added to manage in-plane stresses, then the strength and reliability of the door assembly improve, but the weight and device complexity increase

Engineering Contradiction:

Improvein-plane stress managementVSAvoiddoor assembly weight

Core Design Contradiction:

StrengthVSWeight of stationary object

Solution Approach 1:

The patent merges the door with the fuselage structure by integrating engagement assemblies that directly connect the door to fuselage stringers and ribs. This combination allows the door to function as an integral structural component, eliminating the need for separate reinforcement framing and reducing overall weight while maintaining strength.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The engagement assemblies serve multiple functions: they provide in-plane stress transfer between the door and fuselage, maintain the plug door sealing function, and eliminate the need for additional structural framing. This multi-functionality reduces device complexity and weight while preserving structural strength.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Strength

If extensive structural reinforcement and additional framing are added to manage in-plane stresses, then the strength and reliability of the door assembly improve, but the device complexity increases

Engineering Contradiction:

Improvein-plane stress managementVSAvoiddoor assembly complexity

Core Design Contradiction:

StrengthVSDevice complexity

Solution Approach 1:

The patent merges the door with the fuselage structure by integrating engagement assemblies that directly connect the door to fuselage stringers and ribs. This combination allows the door to function as an integral structural component, eliminating the need for separate reinforcement framing and reducing overall weight while maintaining strength.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The engagement assemblies serve multiple functions: they provide in-plane stress transfer between the door and fuselage, maintain the plug door sealing function, and eliminate the need for additional structural framing. This multi-functionality reduces device complexity and weight while preserving structural strength.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Productivity

If large-size openings are constructed without structural reinforcements, then the productivity and ease of manufacture improve, but the strength may be compromised

Engineering Contradiction:

Improveconversion speedVSAvoidin-plane stress management

Core Design Contradiction:

ProductivityVSStrength

Solution Approach 1:

The patent segments the stress transfer function into discrete engagement assemblies located at specific positions around the door perimeter. These segmented connection points distribute in-plane stresses to the fuselage structure without requiring continuous reinforcement framing, enabling rapid installation while maintaining structural integrity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The engagement assemblies are pre-configured with connection elements that align with existing fuselage stringers and ribs. This preliminary configuration allows the door to be installed quickly without requiring on-site structural modifications or reinforcement additions, maintaining both productivity and strength.

Inventive Principle:

Principle #10Preliminary action

Data Source

PatentUS12263934B2Aircraft plug door with in-plane load transfer capacity and methods of use

Publication Date: 2025.04.01 CURRY JAMES M

AI summary

A plug door assembly for a pressurized aircraft is provided. The door assembly includes a surround and a door, and connector assemblies along the edges that act to transfer in-place stresses directly across the fuselage opening via the door, as well as stops that react redial loads generated by cabin pressure. The door assembly obviates the need for a separate frame to transmit stresses around the perimeter of the fuselage opening.