Shock Strut Servicing Guidance for Trapped Gas and Stroke Control
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Solution Overview
Problem
Conventional shock strut assemblies in aircraft landing gear degrade over time, leading to increased maintenance costs and complexity due to trapped gas issues, requiring time-consuming servicing procedures.
Innovation Solution
A shock strut servicing assistance system that uses sensors to monitor gas temperature, pressure, and stroke, providing automated guidance for adding oil and gas to achieve the correct volume and pressure, simplifying the maintenance process by eliminating the need for reference charts and allowing independent servicing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional single stage shock struts are serviced by lifting the aircraft and cycling the strut multiple times, then trapped gas can be removed, but the servicing process becomes time-consuming and costly
Solution Approach 1:
The patent employs a two-stage shock strut system where the strut can dynamically transition between different compression stages. During servicing, the strut is compressed to the second stage by applying a force greater than the second threshold force, which opens the second check valve and enables rapid drainage of trapped gas through the second orifice, significantly reducing servicing time compared to conventional single-stage cycling methods
Solution Approach 2:
The shock strut is divided into two distinct stages with separate compression thresholds and drainage paths. The first stage handles normal operation with its check valve and orifice, while the second stage provides an accelerated drainage path during servicing. This segmentation allows the system to optimize between operational reliability and servicing efficiency by activating the appropriate stage based on conditions
2Ease of repair
If shock strut assemblies are serviced traditionally requiring aircraft lift and multiple cycling operations, then maintenance can be performed, but maintenance complexity and costs increase
Solution Approach 1:
The shock strut incorporates self-service capabilities through automated valve actuation based on compression threshold detection. When the strut is compressed to the second stage during servicing, the second check valve automatically opens to enable drainage without requiring complex external equipment or multiple manual cycling operations, simplifying the servicing procedure while maintaining effectiveness
Solution Approach 2:
The system prepares for efficient servicing by pre-configuring the two-stage compression system with distinct threshold forces. During normal operation, the strut maintains readiness for rapid drainage by having the second stage mechanism already in place, so that when servicing is initiated and the second threshold force is applied, the accelerated drainage path is immediately activated without requiring complex setup procedures
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 simplifies and speeds up the maintenance process by providing real-time feedback and automated assistance, ensuring accurate oil and gas levels are reached, thereby reducing maintenance time and costs while ensuring the shock strut is properly serviced.
Implementation Method 1
a piston that compresses a fluid within a sealed chamber. The fluid typically includes a gas segment and a liquid segment
Implementation Method 2
a temperature sensor positioned inside the shock strut chamber
Implementation Method 3
a pressure sensor positioned inside the shock strut chamber
Implementation Method 4
a displacement sensor positioned inside the shock strut chamber
Implementation Method 5
calculate a number of moles of gas within the shock strut chamber based on a temperature of the gas, a volume of the shock strut chamber, and an ideal gas law
Data Source
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AI summary
System and methods for servicing and monitoring shock struts are provided. A shock strut servicing assistance system may comprise: a controller in electronic communication with a display; and a tangible, non-transitory memory configured to communicate with the controller, the tangible, non-transitory memory having instructions stored thereon that, in response to execution by the controller, cause the controller to perform operations comprising: sending, by the controller, visible instructions to the display; receiving, by the controller, at least one shock strut parameter; calculating, by the controller, a stroke of a shock strut; comparing, by the controller, the stroke of the shock strut with at least one stroke threshold value; sending, by the controller, an indicator to the display; calculating, by the controller, a volume of an oil located inside of the shock strut; calculating, by the controller, a desired number of moles of a gas; calculating, by the controller, a number of moles of the gas added to the shock strut; and comparing, by the controller, at least one of the desired number of moles of the gas and the number of moles of the gas added to the shock strut with at least one number of moles threshold value.