Flight Control Actuator Secondary Load-Path Engagement Detection
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Solution Overview
Problem
Aircraft flight control actuators face challenges in detecting failures in the primary load path, which can lead to partial or complete loss of control of flight control surfaces, highlighting the need for a reliable system to transition to a secondary load path and announce such transitions.
Innovation Solution
A detection system that includes a secondary mounting assembly guiding axial movement of a secondary rod and a sensor detecting relative axial displacement between the secondary rod and mounting assembly upon primary load path failure, utilizing a spherical joint and targets to indicate engagement in the secondary load path, allowing for electronic annunciation of the transition.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a secondary load path is provided as protection against primary load path failure, then reliability is improved, but device complexity increases
Solution Approach 1:
The load path is segmented into a primary load path (ball screw, drive gimbal, primary ball nut assembly) and a secondary load path (secondary ball nut assembly, secondary drive gimbal). This segmentation allows the system to maintain reliability through redundancy while keeping each segment relatively simple in design.
Solution Approach 2:
The secondary load path components are pre-positioned and ready for immediate engagement before any failure occurs. The secondary ball nut assembly and secondary drive gimbal are arranged in advance to automatically engage when the primary load path fails, eliminating the need for complex detection and switching mechanisms.
2Ease of manufacture
If traditional mechanical detection methods are used for load path failure, then ease of manufacture is improved, but measurement precision deteriorates
Solution Approach 1:
Traditional mechanical detection methods (such as mechanical switches or linkages) are replaced with an optical sensor system. The optical sensor detects the position of the secondary drive gimbal with high precision using non-contact measurement, eliminating the need for complex mechanical detection mechanisms while improving measurement accuracy.
3Measurement precision
If non-contact optical detection is used for secondary load path engagement, then measurement precision is improved, but device complexity increases
Solution Approach 1:
A simple reflective target is used as an intermediary between the optical sensor and the secondary drive gimbal. The target reflects light from the sensor to indicate the engagement state, allowing precise detection without requiring complex sensor assemblies or signal processing systems. This intermediary approach maintains measurement precision while minimizing added complexity.
4Reliability
If immediate detection and annunciation of primary load path failure is implemented, then reliability is improved, but loss of time is reduced
Solution Approach 1:
The optical sensor provides immediate feedback on the position of the secondary drive gimbal, which directly indicates whether the primary load path is engaged or has failed. This feedback is instantly transmitted to the aircraft's annunciation system, providing real-time awareness of the load path status without any time delay for manual detection or interpretation.
Data Source
AI summary
A detection system for detecting failure in a primary load path of a flight control actuator and annunciating engagement in a secondary load path of the flight control actuator. The failure in the primary load path causes axial movement in a secondary rod of the secondary load path. The detection system includes a secondary mounting assembly that guides axial movement of the secondary rod; and a sensor that electronically detects relative axial displacement between the secondary rod and the secondary mounting assembly upon a primary load path failure and annunciates transition to engagement in the secondary load path.