Aircraft Stabilizer Actuator Secondary Load Path Locking Mechanism
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Solution Overview
Problem
Aircraft horizontal stabilizer actuators face catastrophic failure when the primary load path fails, leading to loss of control due to uncontrolled movement and inability to maintain stability during flight.
Innovation Solution
A secondary load path mechanism with a tie rod and load path locking mechanism that locks the stabilizer in a fixed position upon primary path failure, minimizing backlash and allowing for controlled flight and maintenance inspection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a primary load path is used for stabilizer actuation, then the stabilizer can be controllably positioned, but catastrophic failure occurs when the primary load path fails
Solution Approach 1:
The patent implements a secondary load path with locking mechanism that activates upon failure of the primary load path. This pre-positioned backup system cushions against catastrophic failure by automatically engaging to maintain stabilizer control, preventing the harmful effect of complete control loss while preserving the primary system's functionality during normal operation.
2Reliability
If a secondary load path is added for failure protection, then catastrophic failure is prevented, but device complexity increases
Solution Approach 1:
The patent merges the secondary load path functionality into the existing actuator structure by integrating the locking mechanism with the tie rod assembly. The locking mechanism utilizes the same structural components (tie rod, housing) while adding fail-safe functionality, thereby reducing overall system complexity compared to a completely separate backup system.
Solution Approach 2:
The tie rod structure serves multiple functions: it transmits load during normal operation through the primary load path and simultaneously serves as part of the secondary load path structure that can engage the locking mechanism upon failure. This multi-functionality reduces the need for entirely separate backup components, lowering overall system complexity.
3Reliability
If the stabilizer is locked in a fixed position upon failure, then control is maintained, but the stabilizer cannot be repositioned for maintenance inspection
Solution Approach 1:
The patent implements a dynamic locking system where the locking mechanism can transition between locked and unlocked states. During flight, the mechanism automatically locks upon failure to maintain control. During maintenance, the system can be dynamically switched to an unlocked state, allowing stabilizer repositioning while preserving both flight safety and maintenance accessibility.
Data Source
AI summary
A stabilizer actuator has a first end for connecting to an aircraft support structure and a second end for connecting to a stabilizer. The actuator includes a primary load path for transmittal of loads acting on the stabilizer to the aircraft support structure, and a secondary load path for transmittal of loads acting on the stabilizer to the aircraft support structure upon failure of the primary load path. The secondary load path includes a tie rod extending along a longitudinal axis, a load path locking mechanism coupled to the tie rod, a lock housing having a central bore for receiving the locking mechanism, and at least one radially movable segment that, upon failure of the primary load path, moves radially to lock the tie rod to the lock housing against axial and/or radial movement.