Aircraft Load Path Status Detection Using Structural Link Sensors

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Solution Overview

Problem

Current load path detection methods for aircraft are unreliable and prone to false positives, especially in harsh environments, and lack a secondary system to verify primary load path failures, leading to potential safety issues.

Innovation Solution

A load path status detection system that uses a load sensor to measure load on a primary structural link and compares it to a standard, with secondary structural links acting as backups, and a computer system to determine if the primary load path is functioning by analyzing the measurements and providing alerts for failures, while reducing weight and maintenance costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional load path detection methods are used, then the system is simpler, but the reliability of failure detection deteriorates due to false positives and inability to detect hidden fastener failures

Engineering Contradiction:
Improveload path failure detection reliabilityVSAvoiddetection system complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system performs preliminary actions by continuously monitoring load paths during normal operation and establishing baseline load characteristics before failures occur. Load sensors are installed in advance on structural links to capture load data that indicates the health status of fasteners and structural components, enabling detection of degradation trends before actual failure happens.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The system implements feedback mechanisms where load sensor measurements are continuously compared against expected load ranges and historical data. When load patterns deviate from normal operation, the system generates alerts and can trigger backup load paths. This closed-loop feedback enables real-time detection and response to load path failures, significantly improving reliability over traditional static detection methods.

Inventive Principle:
Principle #23Feedback

2Measurement precision

If load sensors are installed on all structural links, then the measurement precision of load path status improves, but the weight of the system increases

Engineering Contradiction:
Improveload status measurement precisionVSAvoidsystem weight
Core Design Contradiction:
Measurement precisionVSWeight of moving object

Solution Approach 1:

The system applies segmentation by dividing the structure into critical load paths and installing sensors only on key structural links that provide the most valuable failure detection information. Rather than uniformly sensoring all links, the system identifies and monitors critical paths where failure would have the greatest impact, reducing sensor count and weight while maintaining effective detection capability through strategic placement.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The load sensors serve multiple functions: they measure current load status, establish baseline characteristics, detect abnormal load patterns indicating fastener degradation, and trigger backup load path activation. This multi-functionality reduces the need for separate detection systems for each function, thereby reducing overall system weight while maintaining comprehensive monitoring capability.

Inventive Principle:
Principle #6Universality (Multi-functionality)

3Measurement precision

If continuous monitoring of all fasteners is performed, then the detection accuracy of fastener integrity improves, but the cost of the system increases

Engineering Contradiction:
Improvefastener integrity detection accuracyVSAvoidmonitoring system cost
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The system uses load sensors on structural links as intermediaries to indirectly monitor fastener integrity. Rather than directly measuring fastener status (which would require complex direct fastener instrumentation), the sensors measure load on the structural links connected by fasteners. Changes in load patterns serve as indicators of fastener health, providing accurate detection at lower cost through this intermediary measurement approach.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The system replaces complex mechanical direct fastener inspection methods with electrical/load-based sensing on structural links. This substitution enables continuous automated monitoring versus periodic manual inspection, improving detection accuracy while reducing long-term costs through automated early warning capabilities that prevent costly failures and maintenance.

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

4Reliability

If backup load paths are added to the system, then the reliability of load transfer improves, but the device complexity increases

Engineering Contradiction:
Improveload transfer reliabilityVSAvoidload path structure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The system implements dynamic load path management where backup load paths are activated only when and where needed based on real-time sensor feedback. Rather than having all backup paths permanently engaged and adding constant complexity, the system dynamically switches between primary and backup paths based on detected failure conditions, maintaining simplicity during normal operation while ensuring reliability when failures occur.

Inventive Principle:
Principle #15Dynamics

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 provides reliable and efficient detection of primary load path failures, reducing false positives and maintenance costs, and ensuring safer operation by using sensors like strain gauges or LVDTs to accurately assess the integrity of primary fasteners and structural links.

Implementation Method 1

sensors like strain gauges or LVDTs to accurately assess the integrity

Methodology Applied
Scientific EffectStrain gauge measurement: Piezoresistive Effect

Implementation Method 2

sensors like strain gauges or LVDTs to accurately assess the integrity

Methodology Applied
Scientific EffectLVDT measurement: Electromagnetic Induction

Data Source

PatentEP3305655B1Load path status detection system
Publication Date: 2023.05.03 THE BOEING CO
  • EP3305655B1 patent drawingFigure 1
  • EP3305655B1 patent drawingFigure 2
  • EP3305655B1 patent drawingFigure 3

AI summary

A load path status detection system (227, 300) comprising a primary fastener (212, 302), a load sensor (208,304), a primary structural link (210, 306), and a secondary structural link (214, 308, 312). The primary fastener (212, 302) extends through the primary structural link. The load sensor (208,304) is associated with the primary structural link. The primary structural link (210, 306) carries a load (330) when a primary load path (232, 310), formed by the primary fastener (212, 302) and the primary structural link (210, 306), is functioning. The secondary structural link (214, 308, 312) is parallel to the primary structural link (210, 306), wherein the secondary structural link (214, 308, 312) does not carry a load when the primary load path (232, 310) is functioning.