Aircraft Flight Control Incidence Protection With One Probe
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Solution Overview
Problem
Modern aircraft flight control computers deactivate the incidence protection mode when fewer than two incidence probes are operational, leaving the aircraft vulnerable to stalling risks.
Innovation Solution
A flight control computer system that uses two dissimilar estimators to compute and verify incidence angle values, allowing the incidence protection mode to remain active even with a single operational probe, by calculating estimated angles and checking consistency, thereby avoiding common failure modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the incidence protection mode is deactivated when fewer than two incidence probes are operational, then the system avoids false protection based on faulty data, but the aircraft becomes vulnerable to stalling risks
Solution Approach 1:
The patent introduces an intermediary validation mechanism that uses alternative data sources (flight control data, aerodynamic models, sensor fusion) to verify incidence angle information when probe data is insufficient. This mediator allows the system to maintain protection mode by cross-validating limited probe data against multiple other sources, thereby reducing stalling risk without relying solely on faulty probe readings.
Solution Approach 2:
The system dynamically changes the parameters used for incidence angle determination based on the number of operational probes. When fewer than two probes are operational, the system transitions from direct probe-based measurement to a composite estimation approach using flight control data, aerodynamic models, and available sensor information, thereby maintaining protection mode availability while adapting to reduced sensor input.
2Object-affected harmful factors
If the incidence protection mode is kept activated with a single operational probe, then the aircraft remains protected from stalling, but the system may act on inconsistent or erroneous incidence data
Solution Approach 1:
The patent implements feedback validation where the incidence angle determined from the single operational probe is continuously cross-checked against flight control data, aerodynamic models, and other sensor information. The system monitors consistency between the probe data and alternative sources, and only maintains protection mode when the probe data passes validation thresholds, thereby preventing action on erroneous data while maintaining protection when data is valid.
Data Source
AI summary
A flight control computer of an aircraft is likely to operate in a so-called incidence protection mode in which it is configured to compute the deflection orders of an elevator as a function of incidence angle values supplied by a set of incidence probes, so as to keep the incidence angle of the aircraft within a range of acceptable incidence angle values. The flight control computer is configured to, when only one incidence probe is operational: compute a first estimated incidence angle value of the aircraft, by a first estimator and a second estimated incidence angle value of the aircraft, by a second estimator unlike the first estimator; and keep the incidence protection mode activated as long as the incidence angle value supplied by the single operational incidence probe is consistent with at least one out of the first estimated incidence angle value and the second estimated incidence angle value.