Aircraft FOHE Failure Detection via Cross-Referenced Temperature Signals
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Solution Overview
Problem
Existing systems for monitoring the health of a Fuel Oil Heat Exchanger (FOHE) in aircraft engines are insufficient as they only provide notification of fuel temperature being outside a predetermined range, failing to distinguish between FOHE failure and sensor faults, leading to potential safety issues like fuel system fires or icing.
Innovation Solution
A method and system that detect out-of-range fuel temperatures downstream of the heat exchanger by monitoring fuel tank and main oil temperatures, using a processing unit to differentiate between FOHE failures and sensor faults, and outputting alerts via a Crew-Alerting System.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuel temperature switch is used to monitor the health of the FOHE, then a notification is provided when fuel temperature is outside a predetermined range, but the information is insufficient to determine if the FOHE or the fuel temperature switch itself is at fault
Solution Approach 1:
The patent introduces an intermediary processing system that receives the fuel temperature switch signal and cross-references it with fuel tank temperature and main oil temperature signals. This intermediary processing layer analyzes the relationships between multiple temperature parameters to determine whether an out-of-range reading indicates actual FOHE failure or sensor fault, thereby resolving the information insufficiency problem
Solution Approach 2:
The system implements feedback by continuously monitoring multiple temperature signals (fuel tank temperature, main oil temperature, and fuel temperature downstream of FOHE) and using this feedback information to validate each other's readings. When discrepancies are detected, the system uses the feedback from multiple sources to identify the faulty component, improving fault detection reliability
2Device complexity
If only fuel temperature downstream of FOHE is monitored, then the system is simple, but it cannot distinguish between FOHE failure and sensor faults
Solution Approach 1:
The monitoring system is designed to serve multiple functions: it not only detects out-of-range fuel temperatures but also identifies the source of the problem (FOHE failure versus sensor fault). By making the system multi-functional through the use of multiple temperature sensors and a processing unit that analyzes relationships between them, the patent achieves both acceptable complexity and high measurement precision
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
This approach allows for reliable detection of FOHE failures, including excessive or insufficient heating conditions, and sensor faults, enhancing safety by providing accurate fault identification and enabling appropriate actions.
Implementation Method 1
The fuel is indeed circulated in the FOHE, where the heat generated by the engine's oil system is transferred to the fuel
Data Source
AI summary
A system and a method for detecting a failure of a heat exchanger provided on an engine of an aircraft. An out-of-range fuel temperature downstream of an outlet of the heat exchanger is detected. A health of a fuel tank temperature signal indicative of a temperature of at least one fuel tank of the aircraft is monitored. A main oil temperature signal indicative of a temperature of oil in the engine is received. The failure is detected based on the main oil temperature and on the health of the fuel tank temperature signal.