Aircraft Engine Oil Fuel Leak Detection Using Magnetic Float

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Solution Overview

Problem

Current methods for detecting fuel leaks in aircraft engine lubrication systems are imprecise, prone to human error, and can only be performed during maintenance, failing to provide real-time diagnosis and immediate action.

Innovation Solution

A magnetic float with adjustable density is used in the lubrication circuit, sinking when fuel mixes with oil to indicate a leak, combined with an oil pressure sensor to confirm the diagnosis.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If smell checks are performed by operators between flights to detect fuel in oil, then detection can be performed, but the method is imprecise, exposed to human error, and relatively time-consuming

Engineering Contradiction:
Improvedetection precisionVSAvoiddetection time
Core Design Contradiction:
Measurement precisionVSLoss of time

Solution Approach 1:

The patent replaces the mechanical/manual smell check method with an automated density-based detection system. A float indicator automatically responds to changes in oil density caused by fuel contamination, eliminating human involvement in the detection process and providing continuous real-time monitoring without time loss between flights.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The float indicator system is self-actuating and requires no external power or manual operation. The float automatically sinks or rises based on the density changes in the oil, providing self-service detection that continuously monitors fuel contamination without requiring operator intervention or consuming additional energy.

Inventive Principle:
Principle #25Self-service

2Reliability

If smell checks are performed by operators between flights, then detection can be performed during maintenance, but real-time diagnosis of leaks during flight is not possible

Engineering Contradiction:
Improvedetection reliabilityVSAvoidoperational convenience
Core Design Contradiction:
ReliabilityVSEase of operation

Solution Approach 1:

The float indicator provides continuous monitoring of fuel contamination in the oil throughout the entire flight operation. Unlike periodic smell checks limited to maintenance intervals, the float continuously responds to density changes, enabling real-time diagnosis of leaks during flight and ensuring immediate awareness of contamination levels without interrupting normal operations.

Inventive Principle:
Principle #20Continuity of useful action

3Measurement precision

If a float with density greater than the oil-fuel mixture is used, then the float sinks to indicate fuel contamination, but the float must have precisely adjustable density to detect specific fuel concentrations

Engineering Contradiction:
Improvefuel content detection precisionVSAvoidfloat manufacturing complexity
Core Design Contradiction:
Measurement precisionVSEase of manufacture

Solution Approach 1:

The patent controls the float's density by adjusting its volume relative to its mass, allowing precise tuning of the detection threshold. By varying the float's volume (while maintaining appropriate mass), the system can be calibrated to sink at specific fuel concentration levels (e.g., 5-35% fuel by volume), enabling precise detection thresholds without complex manufacturing processes.

Inventive Principle:
Principle #35Parameter changes

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 precise, real-time detection of fuel leaks during flight, reducing the risk of self-ignition and ensuring immediate corrective action.

Implementation Method 1

the float has a density greater than a mixture composed, by volume, of X% of the fuel and (100 - X)% of the oil; Since fuel generally has a lower density than oil, any leakage of the former into the latter results in a reduction in the density of the mixture formed, and a reduction in buoyancy and therefore in the emergence of the float

Methodology Applied
Scientific EffectBuoyancy: Archimedes' Principle (Buoyancy)

Data Source

PatentEP4423377B1Detection of the presence of fuel in the oil of an aircraft engine
Publication Date: 2025.07.02 SAFRAN AIRCRAFT ENGINES SAS
  • EP4423377B1 patent drawingFigure 1~2C
  • EP4423377B1 patent drawingFigure 3~4
  • EP4423377B1 patent drawingFigure 5

AI summary

In order to detect possible leaks of fuel into oil used in an aircraft engine when their circuits are connected via a heat exchanger liable to deteriorate, a gauge (22) measuring the liquid level in a tank (2) in which the oil is stored, and incorporated into the oil circuit, is designed so that its float (9) sinks to the bottom of the tank in the event of sufficient leakage, when the density of the mixture becomes lower.