Ram Air Turbine Stow Abort Lock Mechanism
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Solution Overview
Problem
Current stow abort mechanisms for ram air turbines (RATs) in aircraft are costly due to the use of electronic switches, wiring harnesses, and logic circuitry for sensing blade misalignment, which complicates the stowage process and increases expenses.
Innovation Solution
A stow abort mechanism utilizing a spring-loaded stow abort lock pin and a rotating lock plate with an aperture, which engages and disengages to prevent misaligned blade stowage by using a simpler mechanical system instead of electronic components, ensuring proper alignment before allowing deployment and stowage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electronic switch with wiring harness and logic circuitry is used to sense blade misalignment, then the stow abort function is reliable, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the electronic sensing system (switch, wiring harness, logic circuitry) with a purely mechanical sensing mechanism. The mechanical sensor uses a lever arm that physically contacts the turbine release cable lever, detecting blade misalignment through mechanical interaction rather than electrical signals. This substitution eliminates complex electronic components while maintaining the stow abort function's reliability.
Solution Approach 2:
The mechanical sensor system is self-actuating and requires no external power source or control logic. The lever arm automatically engages with the turbine release cable lever and detects misalignment conditions through pure mechanical interaction. The system serves itself by using the existing movement and positioning of RAT components to trigger the stow abort function without requiring additional sensors, power, or electronic control systems.
2Device complexity
If a mechanical sensor system is used instead of electronic components, then the device complexity and cost are reduced, but the measurement precision of blade alignment may be affected
Solution Approach 1:
The patent introduces a lever arm as a mechanical intermediary between the turbine release cable lever and the stow abort lock mechanism. This lever arm physically bridges the gap between the moving RAT components and the locking mechanism, translating blade alignment status into a mechanical position that directly engages or disengages the stow abort lock. The intermediary lever arm ensures precise mechanical coupling without requiring electronic measurement or signal processing.
Solution Approach 2:
The mechanical sensing system is divided into distinct functional segments: the lever arm that detects position, the connection point on the turbine release cable lever, and the engagement mechanism with the stow abort lock. This segmentation allows each component to perform its specific function with high precision - the lever arm purely for detection, the connection point for force transmission, and the lock mechanism for action - thereby maintaining overall measurement precision through functional specialization.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution reduces costs and complexity by providing a reliable mechanical means to prevent blade misalignment during stowage and deployment, ensuring safe and efficient operation of the RAT without the need for expensive electronic components.
Implementation Method 1
A spring-loaded stow abort lock pin replaces the stop that inhibits rotation of the turbine release cable lever
Data Source
AI summary
A stow abort mechanism for a ram air turbine (RAT) with a strut that rotates a turbine with associated blades from a stowed position to a deployment condition comprises a stow abort lock plate with an aperture that rotates with the strut and a stow abort lock pin that engages the aperture in the stow abort lock plate when the blades do not align properly for rotating the strut back into the stowed position.