Landing Gear Controller Uplock Hook Failure Detection
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Solution Overview
Problem
Current aircraft landing gear systems lack effective methods to detect failure of the landing gear uplock hook, which can result in uncommanded extension of the landing gear, as no outward indication or failure signal is issued when the uplock hook fails, potentially leading to safety issues during flight and landing.
Innovation Solution
A landing gear controller that measures the extension time of the landing gear and compares it to a predetermined threshold time, providing a warning signal if the measured time is significantly different, indicating potential failure of the uplock hook, and optionally delays the extension process to increase the time difference between functional and failed uplock hooks, reducing false-positive warnings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the landing gear extension time is measured and compared to detect uplock hook failure, then the detection capability is improved, but the system complexity increases due to timing measurement and comparison mechanisms
Solution Approach 1:
The landing gear controller uses its own existing timing resources and operational data to perform failure detection without requiring external monitoring systems. The controller measures extension time using its internal clock and compares it against stored threshold values, allowing the system to self-diagnose uplock hook failures without adding separate detection hardware.
Solution Approach 2:
The controller implements a feedback mechanism where the measured extension time is continuously compared against predetermined thresholds, and warning signals are generated when abnormal conditions are detected. This closed-loop feedback enables automatic failure detection and alerting without requiring additional external monitoring equipment.
2Reliability
If the landing gear extension is delayed by a predetermined time, then the false-positive warnings are reduced, but the landing gear extension time increases
Solution Approach 1:
The controller applies a preliminary time delay to the landing gear extension command before actual extension begins. This advance timing adjustment allows the system to account for the delay in its extension time measurement, ensuring that the timing window for detecting uplock hook failures remains accurate even though the overall extension process is slightly prolonged.
3Measurement precision
If the extension time threshold is set to be sensitive for detecting failures, then the detection precision is improved, but the false-alarm rate increases
Solution Approach 1:
The controller adjusts the extension time threshold parameter based on operational conditions and applies a compensating time delay. By dynamically modifying the threshold parameter and accounting for the induced delay, the system maintains high detection precision while minimizing false alarms caused by normal variations in extension timing.
Data Source
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Figure 2
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AI summary
Disclosed is a landing gear controller for an aircraft. The controller is configured to: detect an extension time for a landing gear, and if the detected extension time meets a predetermined criterion, provide a warning signal to indicate potential failure of a landing gear uplock hook. Also disclosed is a landing gear system, a method to detect failure of a landing gear uplock hook, and an aircraft.