Aircraft Door Latch Visual Indication for Lock State Verification
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Solution Overview
Problem
Existing aircraft door latch mechanisms rely on unreliable tactile indications for confirming the lock state, which can vary based on the crew member's force and perception, leading to inconsistent verification.
Innovation Solution
A rotary lock-style door latch mechanism with a catch assembly that includes a catch pivotably coupled to a housing, featuring a hook with a visible indicator strip that changes visibility to provide a direct visual indication of the latch's open, security, or lock state, allowing confirmation from outside the aircraft.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If tactile indication methods are used to confirm latch state, then crew members can verify lock state without additional components, but the verification becomes unreliable and inconsistent due to varying force and perception
Solution Approach 1:
The patent applies visual indication through color-coded indicator strips or surfaces that change visibility or appearance based on latch state. The indicator strip on the catch assembly provides distinct visual cues (e.g., visible vs. concealed, different colors) to clearly indicate locked, unlocked, or security states, replacing unreliable tactile verification with reliable visual confirmation.
2Reliability
If visual indication components are added to the latch mechanism, then latch state confirmation becomes reliable and consistent, but the device complexity increases
Solution Approach 1:
The indicator strip serves multiple functions: it provides visual indication of latch state, maintains structural integrity of the catch assembly, and can be integrated with existing latch components. This multi-functionality minimizes the addition of separate components, thereby limiting the increase in device complexity while achieving reliable visual verification.
3Reliability
If the hook completely covers the indicator strip when locked, then security is maximized by concealing the indicator, but visual confirmation of locked state becomes difficult
Solution Approach 1:
The indicator strip is positioned on a specific local area of the catch assembly that is selectively visible or concealed based on latch state. When unlocked, the indicator strip is visible to indicate the open state; when locked, it is concealed by the hook to indicate the secure state. This localized indication provides clear visual information without requiring the indicator to remain constantly visible.
4Loss of information
If the indicator strip remains visible when locked, then visual confirmation is maintained, but security is reduced by exposing the indicator mechanism
Solution Approach 1:
The visibility of the indicator strip dynamically changes based on the latch state. The hook's movement between locked and unlocked positions automatically controls the visibility of the indicator strip, providing real-time visual feedback about the latch state without requiring manual adjustment or additional active components.
Data Source
AI summary
A latch mechanism for a door of an aircraft comprises a striker pin and a catch assembly. The catch assembly includes a housing, which includes a first aperture and a first outboard surface aligned with the first aperture. The catch assembly also includes a catch pivotably coupled to the housing. The catch includes a recess configured to selectively receive the striker pin. The catch also includes a hook extending at least partially through the first aperture. The hook includes a second outboard surface configured to selectively cover the first outboard surface. The catch is pivotable relative to the housing between an open orientation in which the second outboard surface at least partially reveals the first outboard surface, and a lock orientation in which the second outboard surface substantially conceals the first outboard surface. The recess is configured to receive the striker pin when the catch is in the lock orientation.