Aircraft Flight Control Alternate Path
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Solution Overview
Problem
Conventional flight control systems are unable to maintain safe flight and landing when the primary control system becomes unavailable due to common mode faults, leading to severe consequences.
Innovation Solution
A full-time flight critical flight control system with a reversionary mode that provides an independent and dissimilar alternate control path, allowing direct electronic signaling between pilot controls and control surface actuators, independent of the primary flight control system, utilizing software-based control laws and robust alternate control subsystems.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an independent alternate control path is added, then the protection against common mode failures is improved, but the device complexity increases
Solution Approach 1:
The secondary flight control path extracts only the essential control functions needed for safe flight under fault conditions, using direct mode control laws that bypass complex control computers. This extraction approach provides protection against common mode failures while minimizing the addition of system complexity.
Solution Approach 2:
The system creates a simplified copy of the control function through the secondary path, which replicates only the critical control capabilities needed for safe flight without duplicating the full complexity of the primary control system. This allows reliability improvement with controlled complexity increase.
2Device complexity
If the primary control system is simplified, then the device complexity is reduced, but the protection against common mode failures may be compromised
Solution Approach 1:
The system dynamically switches between the primary control path (with full functionality for normal operation) and the secondary control path (with simplified direct mode control for fault conditions). This dynamic adaptation allows the system to maintain appropriate complexity for each operational context while ensuring protection against common mode failures when needed.
Data Source
AI summary
A flight control system and method including a primary flight control path between one or more pilot controls and control surface actuators on an associated aircraft, wherein the primary control path includes one or more flight control computers and one or more first data concentrators; and a secondary flight control path between the one or more pilot controls and the control surface actuators, wherein the secondary flight control path utilizes direct mode control laws to control the control surface actuators; wherein the primary flight control path and the secondary flight control path are independent from each other and the secondary flight control path is operative upon detection of a fault in the primary flight control path.