Aircraft Door Lock Balk Mechanism for Failsafe Latching
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Solution Overview
Problem
Existing aircraft door locks do not have a failsafe mechanism to prevent locking when the aircraft door is not fully closed, which can lead to security and operational issues.
Innovation Solution
The proposed solution involves an aircraft assembly that includes a latch, a balk element, and a fitting. The balk element is rotatable between a balked and an un-balked position, blocking the latch from moving to the locked position when in the balked position. The fitting is configured to push the balk element into the un-balked position as it moves into the closed position, allowing the latch to engage the keeper and secure the door only when it is fully closed.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a door lock is designed to allow easy locking operation, then the ease of operation is improved, but the risk of accidental locking when the door is not fully closed increases
Solution Approach 1:
The balk element is positioned in advance to block the latch path before the door is fully closed. The fitting must first move the balk element out of the way, ensuring that the door is properly positioned before the latch can engage. This preliminary blocking action prevents accidental locking while maintaining ease of operation.
Solution Approach 2:
The balk element acts as an intermediary component between the door and the latch. It mediates the locking process by temporarily blocking the latch path, allowing the system to verify proper door closure before enabling the locking action. This intermediary mechanism adds reliability without significantly complicating the operation.
2Reliability
If a failsafe mechanism is added to prevent locking when the door is not fully closed, then the reliability is improved, but the device complexity increases
Solution Approach 1:
The locking mechanism is segmented into distinct functional components: the balk element for blocking, the fitting for pushing, and the latch for locking. This segmentation allows each component to perform its specific function independently, making the overall system more reliable while keeping individual components simple and easy to manufacture.
Solution Approach 2:
The failsafe mechanism is designed to be self-actuating through the interaction between the fitting and the balk element. As the door is closed, the fitting automatically pushes the balk element out of the way, and the latch automatically engages when the door is properly positioned. This self-service design minimizes the need for additional control systems or complex actuation mechanisms.
3Reliability
If the balk element is decoupled from the latch and made independently rotatable, then the reliability of the failsafe mechanism is improved, but the device complexity increases
Solution Approach 1:
The fitting serves multiple functions: it pushes the balk element out of the way and also guides the door into the correct position for latching. This multi-functionality reduces the need for separate components, maintaining reliability while minimizing the increase in device complexity.
Solution Approach 2:
The balk element is designed to be dynamically positioned - it blocks the latch path when the door is open but can be pushed aside when the door is closed. This dynamic behavior allows the mechanism to adapt to different door positions, ensuring reliable failsafe operation without requiring a completely separate control system for each position.
Data Source
AI summary
An assembly is provided for an aircraft. This aircraft assembly includes a latch, a balk element and a fitting. The latch is movable between an unlocked position and a locked position. The balk element is rotatable between a balked position and an un-balked position. The balk element is configured to block the latch from moving to the locked position when the balk element is in the balked position. The fitting includes a keeper. The fitting is movable between an open position and a closed position. The fitting is configured to push the balk element into the un-balked position as the fitting moves into the closed position. The latch is configured to move to the locked position and engage the keeper when the fitting is in the closed position.