Variable Pitch Propeller Malfunction Detection
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Solution Overview
Problem
There is a need for systems and methods to detect fixed pitch operation of a variable pitch propeller, as malfunctioning propellers operating at fixed pitch can lead to uncontrolled propeller speed, posing a risk to aircraft safety.
Innovation Solution
A method and system that output command signals to adjust the blade angle of a propeller by exchanging oil between a blade angle actuator and a fluid source, assessing changes in rotational speed and blade angle, and detecting fixed pitch operation by determining if changes occur within a predetermined duration, with alerts generated for cockpit annunciation when propeller operation is detected at fixed pitch.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a variable pitch propeller is used to maintain reference speed, then propeller speed control is improved, but the risk of fixed pitch malfunction increases
Solution Approach 1:
The system continuously monitors propeller operation by comparing commanded blade angle changes with actual blade angle measurements and comparing commanded speed changes with actual speed measurements. This feedback mechanism detects when the propeller fails to respond as expected, indicating a fixed pitch malfunction, and generates appropriate alerts to alert the pilot.
Solution Approach 2:
The control system acts as an intermediary between the propeller control mechanisms and the pilot. It monitors the interaction between control commands and propeller responses, detecting discrepancies that indicate malfunction before they lead to unsafe conditions.
2Ease of operation
If blade angle adjustment is made by exchanging oil between actuator and fluid source, then blade angle control is improved, but the complexity of the control system increases
Solution Approach 1:
The system monitors itself by automatically comparing its own commands with the actual responses of the propeller system. The control unit continuously assesses whether commanded blade angle and speed changes are actually occurring, enabling self-detection of malfunctions without requiring additional external monitoring equipment.
3Measurement precision
If fixed pitch operation is detected by monitoring blade angle and speed changes, then detection accuracy is improved, but the response time requirement increases
Solution Approach 1:
The system continuously monitors propeller responses to control commands in real-time, maintaining a ready state for malfunction detection. By continuously comparing commanded versus actual blade angle and speed changes, the system can detect fixed pitch operation immediately when it occurs, without requiring extended observation periods.
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
Effectively detects propeller malfunctions by identifying fixed pitch operation, ensuring propeller speed control and enhancing aircraft safety by providing timely warnings to the crew.
Implementation Method 1
the command signal is output comprising instructions for causing oil to be exchanged between a blade angle actuator of the propeller and a source of fluid to control the blade angle of the propeller
Data Source
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AI summary
A system and method for detecting fixed pitch operation of a variable pitch propeller (130) of an engine (110). A command signal for maintaining a rotational speed of the propeller (130) at a reference speed is output. An actual value of at least one of the rotational speed and a blade angle of the propeller (130) is obtained. From the actual value, it is assessed whether an expected change in the at least one of the rotational speed and the blade angle of the propeller (130) has occurred in response to the command signal. Responsive to determining that the expected change in the at least one of the rotational speed and the blade angle of the propeller (130) has not occurred in response to the command signal, operation of the propeller (130) at fixed pitch is detected and an alert output accordingly.