Aircraft Hard Landing Indicator Hydraulic Plunger Mechanism

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Solution Overview

Problem

Conventional methods for detecting hard landings in aircraft are subjective and unreliable, leading to potential structural damage going unnoticed or resulting in unnecessary inspections, as they rely on pilot declarations and are time-consuming.

Innovation Solution

A hard landing indicator assembly that includes a pressure relief valve, hydraulic tube, plunger, and gland nut, where the plunger extends outward to indicate a hard landing event by increasing pressure within the hydraulic tube, allowing oil to enter and overcome a spring force, visibly signaling ground support staff through a dynamic seal and stop mechanism.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If pilot declaration is used to detect hard landings, then the detection method is simple to implement, but the reliability of detection is poor

Engineering Contradiction:
Improveease of implementationVSAvoiddetection reliability
Core Design Contradiction:
Ease of manufactureVSReliability

Solution Approach 1:

The patent replaces the subjective mechanical judgment system (pilot declaration) with an objective hydraulic-mechanical indicator system. The indicator assembly uses hydraulic pressure from the shock strut to automatically trigger a visual indication when hard landing conditions are detected, eliminating reliance on pilot subjectivity while maintaining simple implementation through direct mechanical-hydraulic coupling.

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

2Reliability

If comprehensive inspection is conducted after hard landing declaration, then structural damage can be detected, but aircraft downtime increases

Engineering Contradiction:
Improvedamage detection accuracyVSAvoidaircraft downtime
Core Design Contradiction:
ReliabilityVSLoss of time

Solution Approach 1:

The patent performs preliminary detection action by providing continuous visual indication of hard landing events through the indicator assembly. The indicator proactively signals potential damage conditions before inspection occurs, allowing maintenance personnel to prioritize and target inspections based on actual hard landing evidence rather than conducting routine comprehensive inspections after every landing.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The patent implements feedback by creating a closed-loop information system where the indicator assembly continuously monitors shock strut hydraulic conditions and provides immediate visual feedback about hard landing events. This feedback mechanism enables real-time awareness of potential structural issues without requiring continuous inspection cycles.

Inventive Principle:
Principle #23Feedback

3Reliability

If frequent inspections are performed to ensure safety, then structural integrity can be monitored, but resource expenditure increases

Engineering Contradiction:
Improvestructural safety monitoringVSAvoidresource expenditure
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The patent enables self-service detection by allowing the indicator assembly to automatically monitor and signal hard landing conditions without requiring external inspection resources. The system uses its own hydraulic pressure from the shock strut to drive the indicator mechanism, eliminating the need for external power sources or complex electronic systems while maintaining continuous safety monitoring.

Inventive Principle:
Principle #25Self-service

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

Provides a robust and cost-effective solution for reliably identifying hard landings, reducing downtime and resource expenditure by visually indicating damage, allowing for targeted inspections and faster servicing of aircraft landing gear.

Implementation Method 1

a liquid disposed within the hydraulic tube between the pressure relief valve and the top portion of the plunger, the liquid applying a first force in a first direction to the top portion of the plunger

Methodology Applied
Scientific EffectHydraulic pressure: Pressure Increase

Implementation Method 2

a spring coupled to the plunger, the spring applying a second force in a second direction to the top portion of the plunger

Methodology Applied
Scientific EffectSpring force: Spring

Data Source

PatentEP4382420A1Aircraft hard landing indicator
Publication Date: 2024.06.12 GOODRICH CORP
  • EP4382420A1 patent drawingFigure 1
  • EP4382420A1 patent drawingFigure 2A
  • EP4382420A1 patent drawingFigure 2B

AI summary

A hard landing indicator assembly (202) is disclosed herein. The hard landing indicator assembly includes a pressure relief valve (230), a hydraulic tube (232) having a first end and a second end, the first end coupled to the pressure relief valve (230), and a plunger (238) having a top portion and a shaft (23 8b), the plunger disposed in the hydraulic tube (232), wherein a portion of the shaft (23 8b) is a hard landing indicator (234) that extends outward from the hydraulic tube (232) in response to a hard landing event.