Aircraft Pump Fuel Flow Rate Diagnostic Method
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Solution Overview
Problem
Current methods for determining the restart capability of an aircraft turbine engine's high pressure pump are inadequate, as they rely on pressure measurements and extrapolation of fuel flow rates, leading to potential overestimation of pump deterioration and unnecessary maintenance or replacement of functional pumps.
Innovation Solution
A method that involves rotating the high pressure pump to a predetermined speed, supplying fuel to one or more cylinders, and directly measuring the fuel flow rate to determine if it meets the required restart capacity for the combustion chamber, using an electric or pneumatic starter, and accounting for ground and flight conditions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pressure measurement and extrapolation methods are used to assess pump flow rate, then the assessment process is simple, but the measurement precision is insufficient leading to potential overestimation of pump deterioration
Solution Approach 1:
The patent replaces indirect pressure-based assessment with direct mechanical measurement of fuel flow rate using a flow meter. This substitution of measurement methodology eliminates extrapolation errors and provides accurate real-time flow rate data, directly resolving the measurement precision issue while maintaining acceptable system complexity through integration of standard flow measurement components.
2Reliability
If systematic replacement or maintenance of high pressure pump is performed after a given operating time period, then the turbine engine restart capability is ensured, but unnecessary maintenance or replacement of functional pumps occurs
Solution Approach 1:
The patent implements a feedback-based diagnostic system that continuously monitors actual fuel flow rate and compares it against minimum required thresholds for restart capability. This feedback mechanism enables condition-based maintenance decisions, replacing pumps only when actual performance degradation confirms inability to meet restart requirements, thereby eliminating unnecessary replacements while ensuring reliability.
Solution Approach 2:
The diagnostic system enables the pump system to self-assess its own performance status through continuous flow rate monitoring and automatic comparison with operational thresholds. This self-service capability allows the system to determine its own maintenance needs based on actual performance rather than predetermined time schedules, reducing unnecessary maintenance interventions.
3Speed
If the high pressure pump operates at autorotation speed, then the turbine engine can rotate without propulsion, but the fuel flow rate supplied is limited and may be insufficient for restart
Solution Approach 1:
The patent performs preliminary assessment of pump performance at autorotation speeds before flight operations. By measuring fuel flow rate at the specific low speed condition of autorotation (approximately 6% of takeoff speed), the system determines in advance whether the pump can deliver sufficient fuel quantity for restart, enabling prediction of restart capability without actually attempting an in-flight restart.
Data Source
AI summary
The invention proposes a method for determining the capacity of an aircraft pump to deliver a predetermined fuel flow rate,characterised in that it comprisesa step of rotating the pump at a predetermined speed;a step of supplying at least one cylinder with the totality of the fuel coming out of the pump;a step of determining the fuel flow rate supplying said cylinder, anda diagnostic step which consists in determining whether the pump is able to supply a sufficient flow rate as a function of the determined value of the flow rate supplying the cylinder.The invention also proposes a device implementing the method.