Landing Gear Shock Strut Servicing via Fluid Saturation Mixing

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Servicing unseparated aircraft landing gear shock absorbers without jacking the aircraft is challenging due to unknown liquid and gas saturation levels, leading to inaccurate measurements and potential compromise of landing performance.

Innovation Solution

A method and apparatus that set the working fluid in a known equilibrium state by mixing the liquid and gas until the liquid is fully saturated, allowing for accurate measurements and operations while the aircraft is supported, using a mixer to circulate and saturate the fluid within the shock absorber.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of time

If the shock absorber is serviced without jacking the aircraft, then servicing time is reduced and simplicity is improved, but measurement accuracy deteriorates due to unknown liquid-gas saturation levels

Engineering Contradiction:

Improveservicing timeVSAvoidmeasurement accuracy

Core Design Contradiction:

Loss of timeVSMeasurement precision

Solution Approach 1:

The mixer is activated before servicing measurements are taken to pre-establish the liquid-gas saturation equilibrium. This preliminary mixing action ensures that the working fluid reaches a known saturation state before any measurements or servicing operations commence, thereby maintaining measurement accuracy even when the aircraft is not jacked up.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system changes the physical state parameters of the working fluid by actively mixing the liquid and gas phases to achieve saturation. By controlling the mixing process and establishing equilibrium conditions, the system transforms the unknown saturation state into a known, measurable state, enabling accurate servicing measurements while the aircraft remains on the ground.

Inventive Principle:

Principle #35Parameter changes

2Device complexity

If the liquid and gas are kept unseparated in the shock absorber, then device complexity is reduced, but the ability to determine gas dissolution in liquid deteriorates

Engineering Contradiction:

Improvedevice complexityVSAvoidgas dissolution information

Core Design Contradiction:

Device complexityVSLoss of information

Solution Approach 1:

The mixer acts as an intermediary device that facilitates the mixing of liquid and gas phases while allowing the unseparated shock absorber design to be maintained. This intermediary tool enables the determination of gas dissolution levels in the liquid without requiring complex internal separation mechanisms, thus preserving the simple unseparated design while providing the necessary information about gas-liquid saturation.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If the shock absorber is pressurised to achieve specific extension length, then shock absorber performance is improved, but the difficulty of determining saturation levels increases

Engineering Contradiction:

Improveshock absorber performanceVSAvoidsaturation level detection

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The system uses feedback from measurements taken after mixing to determine the saturation level of the working fluid. By measuring parameters such as pressure, temperature, and shock absorber extension length after the mixing process, the system can calculate and verify the gas dissolution level in the liquid, providing feedback that confirms the saturation state even under pressurised conditions.

Inventive Principle:

Principle #23Feedback

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 faster, simpler, and more accurate servicing of shock absorbers by determining gas dissolution in the liquid, reducing the need for jacking and improving landing performance by ensuring precise gas and liquid quantities.

Implementation Method 1

mixing the liquid and the gas within the chamber until the liquid is uniformly saturated with the gas

Methodology Applied

Scientific EffectMixing: Stirring

Implementation Method 2

the liquid is uniformly saturated with the gas

Methodology Applied

Scientific EffectGas dissolution: Absorption (physical)

Data Source

PatentEP3498603B1Method of servicing an aircraft landing gear shock absorbing strut

Publication Date: 2022.01.26 MESSIER DOWTY

Figure 1~2
Figure 3~4

AI summary

A method of servicing a shock absorber of an aircraft landing gear shock absorbing strut (12), the shock absorber including a sealed, variable volume chamber containing a liquid and a gas in fluid communication with one another, the method comprising: using a mixer (14) to mix the liquid and the gas within the chamber until the liquid is uniformly saturated with the gas; and subsequently performing one or more servicing actions.