Aircraft Door Alignment with Ball Transfers for Deformed Frames
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Solution Overview
Problem
Aircraft doors, particularly large cargo doors, experience significant deformation when opened, leading to difficulties in closing due to mismatched shapes between the door and doorframe, and existing lock mechanisms may not allow easy emergency exit or safe opening in case of jamming without risking damage to the aircraft.
Innovation Solution
A door system with a ball transfer unit, load fittings, and shear ties that realign the doorframe to match the door shape, combined with a lock defeat mechanism for easy interior access and backup pin systems for external opening, ensuring safe and efficient closure and emergency access.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If the door is made large to allow cargo passage, then the cargo loading capability is improved, but the door and doorframe experience significant deformation when opened, making closure difficult
Solution Approach 1:
The ball transfer unit is engaged before final door closure to pre-align the door with the doorframe, compensating for deformation that occurs when the large door is opened. This preliminary alignment action prevents closure difficulties despite the door's large size.
Solution Approach 2:
The ball transfer unit acts as an intermediary mechanism between the door and doorframe, facilitating alignment and reducing the direct contact forces that cause deformation. This mediator enables seamless closure of the large door without excessive force.
2Reliability
If traditional lock mechanisms are used, then the door can be secured, but emergency exit or opening becomes difficult without risking damage to the aircraft
Solution Approach 1:
The door opening system is segmented into multiple independent mechanisms: the primary latching arrangement for normal operation, and backup pin systems (including a second pin system accessible from outside) for emergency situations. This segmentation allows the door to be opened safely through different paths depending on the situation, maintaining both security and emergency accessibility.
Solution Approach 2:
The lock defeat mechanism allows the primary latching arrangement to be disengaged or 'discarded' in emergency situations through the backup pin systems, enabling door opening without damaging the aircraft structure. The system recovers functionality by providing alternative opening paths when the primary mechanism becomes problematic.
3Ease of operation
If the door is closed forcefully to overcome deformation mismatch, then the door can be secured, but excessive force may damage the aircraft
Solution Approach 1:
The ball transfer unit and load fittings perform preliminary alignment of the door with the doorframe before final closure, eliminating the need for excessive closing force. This pre-positioning action prevents harmful impacts while enabling seamless door closure.
Solution Approach 2:
The ball transfer unit serves as a mediator that absorbs and distributes forces during door closure, preventing concentrated excessive forces that could damage the aircraft. This intermediary mechanism enables the door to be closed easily without creating harmful effects on the airframe.
Data Source
AI summary
An aircraft door system and related closure method. The system involves the use of a ball transfer device as an initial contact made in the closing of an aircraft door. The closing door next encounters guiding and fitting arrangements are also employed to laterally align the lower portion of the aircraft door with the corresponding portion of the frame upon the closing. Finally, the closing door then encounters load path ties which are employed about the door. The arrangement above allows the door refit the door within what is a deformed doorframe due to weight and structural considerations.