Engine Fuel Control System Overthrust Protection
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Solution Overview
Problem
Existing fuel control systems for gas turbine engines face challenges in managing thrust imbalances caused by fuel metering valve failures, leading to overthrust conditions, which can result in engine shut-downs that are not safe at all flight conditions, particularly during landing approaches.
Innovation Solution
An engine fuel control system that includes a pressure sensor to monitor fuel pressure between fuel pumps and the metering valve, allowing for improved fuel flow management and engine health monitoring, enabling the engine controller to take corrective actions to prevent engine shut-down and maintain safe operation during overthrust conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fuel control system shuts down the engine in response to a metering valve failure causing overthrust, then the engine is protected from overspeed induced failure, but thrust asymmetry rapidly reverses and acts in the opposite direction which may not be safe at certain flight conditions such as landing approach
Solution Approach 1:
The system converts the harmful overthrust condition caused by metering valve failure into a beneficial controlled state by using the excess fuel pressure to drive a governor mechanism that automatically adjusts the fuel flow. The harmful high fuel pressure that causes overthrust is transformed into a useful signal that triggers the governor to reduce fuel flow back to the desired level, thereby protecting the engine while maintaining safe thrust levels without shutdown
Solution Approach 2:
The governor mechanism implements a feedback control system where the actual fuel pressure is continuously monitored and compared with the desired fuel pressure. When overthrust is detected through high fuel pressure, the governor automatically adjusts the fuel metering in real-time to reduce pressure back to the target level. This closed-loop feedback ensures the engine remains protected while maintaining safe operational thrust levels during landing approach and other critical flight conditions
2Reliability
If a pressure sensor is added to monitor fuel pressure for overthrust detection and control, then fuel flow management is improved and engine health monitoring is enabled, but device complexity increases
Solution Approach 1:
The pressure sensor serves multiple functions simultaneously: it monitors fuel pressure for overthrust detection, provides feedback for the governor control mechanism, and enables engine health monitoring for maintenance scheduling. By making the pressure sensor a multi-functional component that serves detection, control, and diagnostic purposes, the system achieves improved reliability without proportionally increasing complexity
Solution Approach 2:
The patent combines the pressure sensing function with the existing governor control mechanism and engine monitoring systems. The pressure sensor is integrated into the fuel control system's existing architecture, sharing signal processing and control logic with other engine parameters. This merging of functions reduces the overall system complexity compared to having separate independent systems for pressure monitoring, thrust control, and health diagnostics
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
The system effectively manages overthrust conditions by reducing fuel flow and implementing thrust control malfunction accommodation procedures, while also monitoring engine health to prevent failures and optimize fuel delivery, thereby ensuring safe and controlled engine operation.
Implementation Method 1
a pressure sensor arranged to sense the pressure of fuel on the supply line between the one or more fuel pumps and the fuel metering valve, or arranged to sense the pressure of the fuel on the delivery line between the fuel metering valve and the pressure raising arrangement
Data Source
AI summary
An engine fuel control system includes a fuel metering valve operable to control the flow of fuel between a supply line and a delivery line. The delivery line is configured to receive fuel from one or more fuel pumps. The engine fuel control system further includes a pressure raising arrangement which receives the fuel flow from the delivery line and raises the fuel pressure therein. The engine fuel control system further includes a pressure sensor arranged to sense the pressure of the fuel in the supply line between the one or more fuel pumps and the fuel metering valve, or to sense the pressure of the fuel in the delivery line between the fuel metering valve and the pressure raising arrangement.