RAT Door Linkage Motion Limiter for Over-Rotation Protection
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Solution Overview
Problem
Aircraft ram air turbine (RAT) door linkages are prone to over-rotation during handling and installation, leading to potential damage from stress concentrations and fatigue due to the lack of rotational limiters.
Innovation Solution
A motion limiter system is integrated into the door linkage, comprising a block with openings and tabs that engage the clevis cavity apex to limit rotation, preventing metal-to-metal contact and damage by acting as a soft stop during handling and installation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the door linkage is left without rotational limiters to simplify the structure, then the device complexity is reduced, but the reliability deteriorates due to over-rotation damage during handling and installation
Solution Approach 1:
The motion limiter is a pre-installed protective component that acts as a cushion or stop to prevent over-rotation damage before it can occur. The limiter includes a motion limiter arm with a stop feature that physically blocks the linkage from rotating beyond its safe range, protecting the clevis and other components from stress concentrations and fatigue during handling and installation.
Solution Approach 2:
The motion limiter arm serves as an intermediary component between the first and second linkages. It mediates the rotational motion by providing a controlled range of movement through the stop feature, allowing necessary rotation for deployment while preventing excessive rotation that would cause damage.
2Reliability
If motion limiters are added to prevent over-rotation damage, then the reliability improves, but the device complexity increases
Solution Approach 1:
The motion limiter is designed as a separate, modular component (motion limiter arm) that can be independently attached to the linkage system. This segmentation allows the protective function to be added without redesigning the entire linkage, making the complexity manageable and the component easily replaceable if needed.
Solution Approach 2:
The motion limiter changes the rotational parameter of the linkage by imposing a physical constraint on the angle of rotation. The stop feature on the motion limiter arm defines specific angular limits, transforming the uncontrolled rotation parameter into a controlled parameter with defined boundaries.
3Adaptability or versatility
If the linkage allows full rotation range for proper RAT deployment, then the adaptability improves, but the risk of over-rotation damage increases
Solution Approach 1:
The motion limiter provides dynamic control of the linkage rotation. The stop feature is positioned to allow the linkage to rotate freely through the necessary range for RAT deployment, then dynamically engages to prevent further rotation. This creates a flexible system that adapts to deployment needs while protecting against excessive motion.
Data Source
AI summary
Disclosed is an aircraft system comprising: a linkage comprising a first end, an opposing second end and a clevis therebetween; a motion limiter configured to engage the clevis; wherein: the first end is configured for connecting to one of a strut of a ram air turbine (RAT) and an enclosure door, and the second end is configured for connecting with another of the strut and the door; and the motion limiter limits rotation between the first end of the linkage and the second end of the linkage.