Inner Fixed Structure Latch for Gas Turbine Thrust Reverser
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Solution Overview
Problem
The inner fixed structure (IFS) of a gas turbine engine's thrust reverser can deflect radially outward during overpressure events, potentially causing damage and loss of structural integrity due to scooping high-velocity air, and existing latch assemblies fail to adequately prevent such deflections while allowing for normal operational deflections.
Innovation Solution
The introduction of pin and cam latch assemblies with a moveable portion, handle, and flexible cable system, where the latch assemblies are configured to be in a waiting-fail-safe load path, allowing normal deflections while engaging a load path during severe overpressure events to prevent excessive IFS deflection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If the IFS is allowed to deflect freely during normal operation, then operational flexibility is maintained, but during overpressure events the IFS may deflect excessively and damage structural integrity
Solution Approach 1:
The latch assembly employs a moveable portion that dynamically transitions between engaged and disengaged states. During normal operation, the moveable portion remains disengaged, allowing the IFS to deflect freely for operational flexibility. During overpressure events, the moveable portion engages with the receiver to form a load path, preventing excessive deflection and protecting structural integrity.
Solution Approach 2:
The latch assembly acts as an intermediary mechanism between the IFS and the engine case. The moveable portion serves as a mediator that selectively connects or disconnects the load path based on pressure conditions, enabling the system to switch between flexible operation and rigid protection modes.
2Reliability
If a latch assembly is designed to prevent all deflection, then structural integrity is maintained, but normal operational deflections are restricted
Solution Approach 1:
The latch assembly is pre-configured with a waiting-fail-safe load path that remains inactive during normal operation. The moveable portion is positioned to allow free deflection but is designed to automatically engage and prevent excessive deflection when overpressure conditions occur, providing preliminary protection without restricting normal operations.
Solution Approach 2:
The latch assembly transitions from a static restraint system to a dynamic selective restraint system. The moveable portion enables the latch to adapt its restraint level based on operational conditions, providing freedom during normal operation and automatic engagement during overpressure events.
3Reliability
If the latch assembly engages during normal operation, then the IFS is restrained, but the latch assembly must disengage to allow operational deflections
Solution Approach 1:
The latch assembly is designed as a self-actuating system where the moveable portion automatically engages or disengages based on the pressure conditions and IFS deflection. The system monitors its own state through the mechanical interaction between the moveable portion and the IFS, eliminating the need for external control mechanisms or complex actuation systems.
4Reliability
If a rigid latch structure is used, then overpressure protection is ensured, but the latch cannot accommodate normal operational movements
Solution Approach 1:
The latch assembly transforms from a rigid fixed structure to a dynamic adaptive structure. The moveable portion enables the latch to provide rigid restraint when needed for overpressure protection while maintaining flexibility to accommodate normal operational movements through its ability to disengage or remain inactive during routine operations.
Data Source
AI summary
Pin latch assemblies and cam latch assemblies are disclosed. A pin latch assembly is provided comprising a pin housing at least partially enclosing a pin, an actuating device coupled to the pin, and a retaining feature comprising an aperture.