Flight Control Pneumatic Fault Detection Using Dynamic Pressure Rate
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Solution Overview
Problem
Flight control systems face challenges in accurately detecting common mode pneumatic events, such as pitot tube blockages, which can lead to inaccurate airspeed calculations and unnecessary mode switches, due to the immediate switching from normal to secondary operation without isolating the source of error.
Innovation Solution
A flight control system that determines a common mode pneumatic event by comparing the rate of change of measured dynamic pressure with a threshold value and the rate of change of estimated angle of attack, allowing for substitution of measured dynamic pressure with estimated dynamic pressure to maintain normal operation and delay the switch to secondary mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the flight control system immediately switches from normal to secondary operation when a pitot tube fault is detected, then the system responds quickly to potential failures, but this causes false alarms and unnecessary mode switches that disrupt aircraft operation
Solution Approach 1:
The system performs preliminary analysis by calculating the rate of change of dynamic pressure and comparing it with threshold values before confirming a fault. This preliminary action allows the system to distinguish between actual common mode pneumatic events and transient anomalies, preventing false alarms while maintaining quick response to genuine failures
Solution Approach 2:
The system continuously monitors dynamic pressure and its rate of change, using feedback loops to compare current readings with threshold values. This feedback mechanism enables real-time fault detection while allowing temporary deviations without triggering mode switches, thus maintaining operational stability
2Measurement precision
If the flight control system uses multiple pitot tubes to measure dynamic pressure, then the measurement accuracy improves, but the complexity of detecting common mode failures increases
Solution Approach 1:
The system transforms the fault detection problem from comparing multiple pressure values to analyzing the rate of change of dynamic pressure. By changing the parameter from static pressure comparison to dynamic rate-of-change analysis, the system simplifies the detection logic while maintaining the ability to identify common mode failures across multiple pitot tubes
Solution Approach 2:
The system extracts the essential fault indicator by focusing solely on the rate of change of dynamic pressure rather than analyzing all individual pitot tube readings. This extraction approach simplifies the detection system by identifying the key parameter that indicates common mode failures, reducing computational complexity
Data Source
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AI summary
A flight control system (18) for an aircraft is disclosed, where the flight control system (18) detects a first common mode pneumatic event. The flight control system includes one or more processors (1030) and a memory (1034) coupled to the processors (1030). The memory (1034) stores data comprising a database (1044) and program code that, when executed by the one or more processors (1030), causes the flight control system (18) to receive as input a measured dynamic pressure and an estimated angle of attack. The flight control system (18) is further caused to determine a rate of change of the measured dynamic pressure and compare the rate of change of the measured dynamic pressure with a dynamic pressure threshold value. The flight control system (18) is further caused to determine a rate of change of the estimated angle of attack and compare the rate of change of the estimated angle of attack with a threshold angle of attack.