Flexible Fuel Dam Deflection Management

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Solution Overview

Problem

Aircraft fuel tanks face challenges with sealant cracking due to deflection caused by temperature changes and weight, leading to potential fuel leaks, especially in 'wet wing' configurations, where mechanical fastening is heavy, costly, and difficult to assemble, and existing solutions either add weight or compromise seal integrity.

Innovation Solution

A fuel dam system with a flexible second portion that accommodates deflection between the stringer and rib, eliminating the need for fasteners in areas of low deflection and using adhesives to bond the fuel dam to both structures, thereby reducing weight, complexity, and cost while maintaining seal integrity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If mechanical fasteners are used to connect the fuel barrier to the wing structure, then the seal integrity is improved, but the weight and complexity of the system increase

Engineering Contradiction:

Improveseal integrityVSAvoidfastener system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces mechanical fasteners with a chemical bonding system using sealant and adhesive. The fuel barrier is bonded to the wing structure through a multi-layer sealing system comprising a first sealant between the fuel barrier and skin, and a second sealant between the fuel barrier and rib, eliminating the need for mechanical fasteners while maintaining seal integrity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the bonding mechanism from mechanical to chemical by using sealants and adhesives with specific properties. The sealant is formulated to cure and bond the fuel barrier to the wing structure, providing both structural attachment and sealing functionality without the complexity of mechanical fastening systems.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If mechanical fasteners are used to connect the fuel barrier to the wing structure, then the seal integrity is improved, but the weight of the system increases

Engineering Contradiction:

Improveseal integrityVSAvoidfuel barrier system weight

Core Design Contradiction:

ReliabilityVSWeight of moving object

Solution Approach 1:

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Ease of manufacture

If sealant is used to seal the fuel barrier, then the ease of assembly is improved, but the sealant may crack under deflection leading to fuel leaks

Engineering Contradiction:

Improveassembly easeVSAvoidseal integrity

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies different sealant configurations in different locations to address local requirements. A first sealant is used between the fuel barrier and skin, while a second sealant is used between the fuel barrier and rib. This localized approach allows each sealant to be optimized for its specific position and the deflection characteristics of that area.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent uses a composite sealing system combining multiple sealants with different properties. The first and second sealants work together in a multi-layer configuration, with each sealant providing specific sealing functions in different locations, creating a more robust overall sealing system that can accommodate deflection without cracking.

Inventive Principle:

Principle #40Composite materials

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 solution effectively manages deflections without compromising seal integrity, reducing the need for fasteners, lowering installation and maintenance costs, and allowing for spark-free protection without access holes, thus enhancing the structural integrity and reducing the likelihood of fuel leaks.

Implementation Method 1

The second portion is more flexible than the first portion... The second portion accommodates deflection between the first body and the second body

Methodology Applied

Scientific EffectElasticity: Elasticity

Data Source

PatentUS8167245B1Fuel barrier

Publication Date: 2012.05.01 THE BOEING CO

AI summary

Embodiments of the present disclosure provide an apparatus, method, and system for managing deflections comprising a fuel dam, a first portion of the fuel dam connected with a stringer, a second portion of the fuel dam connected with the first portion, and a third portion of the fuel dam. The second portion is more flexible than the first portion. The third portion is connected with the second portion, and connected with a rib. The second portion accommodates deflection between the stringer and the rib.