Air-Data-Probe Heater Failure Prediction via Leakage-Current Sensing
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Solution Overview
Problem
Unexpected failures of air data probe heaters lead to flight delays and maintenance costs, primarily due to the failure of resistive heating elements, which are prone to leakage current issues due to insulation degradation and capacitance between the heater wire and metallic sheath.
Innovation Solution
A system using an electrical power source, sensor, and prediction engine to monitor phase relations and high-frequency components of electrical metrics, such as voltage and current, to predict failure or estimate the remaining useful life of the resistive heating element based on leakage current behavior.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a resistive heating element is used to prevent ice buildup in air data probes, then operational reliability is improved, but leakage current increases due to insulation degradation and capacitance between the heater wire and metallic sheath
Solution Approach 1:
The system performs preliminary monitoring of electrical metrics (voltage, current, phase relations) to detect early signs of insulation degradation and capacitance changes. By identifying degradation trends before complete failure occurs, the system enables pre-emptive maintenance that prevents operational failures while managing leakage current issues proactively
Solution Approach 2:
The system continuously monitors electrical metrics including voltage, current, and phase relations between leakage current and operating power. This feedback mechanism tracks insulation resistance degradation and capacitance changes over time, allowing the system to assess heater health status and predict remaining useful life based on measured parameter trends
2Loss of time
If continuous monitoring of electrical metrics is implemented to predict heater failure, then maintenance timing is optimized, but system complexity increases
Solution Approach 1:
The monitoring system uses multi-functionality by measuring multiple electrical parameters (voltage, current, phase relations) with a single integrated system. The same measurement infrastructure serves both operational monitoring and failure prediction functions, reducing the need for separate dedicated sensors and simplifying the overall system architecture
Solution Approach 2:
The system leverages the existing electrical operating power and inherent leakage current paths as the monitoring mechanism. By analyzing the natural electrical characteristics already present in the heater circuit, the system performs self-diagnosis without requiring external test equipment or additional power sources, thereby minimizing added system complexity
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enables proactive maintenance by predicting heater failures, reducing flight delays and maintenance costs through accurate estimation of the heater's remaining life based on electrical metrics.
Implementation Method 1
The electrical sensor senses voltage and/or current of the electrical operating power provided to the resistive heating element
Implementation Method 2
The signal comparator determines a phase relation of a leakage current with respect to the voltage and/or current of the electrical operating power provided to the resistive heating element
Implementation Method 3
Air data probes typically include resistive heater elements to prevent operational issues relating to in-flight ice buildup
Implementation Method 4
The insulator creates a very high electrical resistance between the metallic sheath (often electrically connected to the body of the probe) and the heater wire itself
Implementation Method 5
The presence of the heater wire, insulator, and metallic sheath also creates a capacitance between the sheath and the heater wire
Data Source
AI summary
Apparatus and associated methods relate to predicting failure and/or estimating remaining useful life of an air-data-probe heater. Failure is predicted or useful life is estimated based on an electrical metric of the electrical operating power provided to a resistive heating element of the air-data-probe heater. The electrical metric of the air data probe heater is one or more of: i) phase relation between voltage across the resistive heating element and leakage current, which is conducted from the resistive heating element to a conductive sheath surrounding the resistive heating element; ii) a time-domain profile of leakage current through the heating element insulation during a full power cycle; and/or iii) high-frequency components of the electrical current conducted by the resistive heating element and/or the voltage across the resistive heating element.