Fuel Stringer Duct Connector With Internal Flange Sealing

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Solution Overview

Problem

Existing connectors for fuel stringer ducts in aircraft are prone to damage and have difficulty forming a reliable seal due to manufacturing tolerances and the need for post-cure machining to ensure a fluid-tight connection.

Innovation Solution

A connector design featuring a flange with an o-ring sealing member that forms a seal between the flange and the internal surface of a hole in the fuel stringer duct, allowing for consistent sizing and reduced sensitivity to manufacturing variations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a connector is bonded to the fuel stringer duct using adhesion or co-curing, then the connection strength is improved, but the connector becomes difficult to remove and replace when damaged

Engineering Contradiction:
Improveconnection strengthVSAvoidease of replacement
Core Design Contradiction:
StrengthVSEase of repair

Solution Approach 1:

The connector is divided into separate components: a removable connector body and a flange that remains with the fuel stringer duct. The flange is inserted into a hole in the FSD and secured with fasteners, while the connector body can be detached and replaced independently, enabling easy repair without replacing the entire assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The connection system transitions from a permanent bonded joint to a dynamic, removable mechanical connection. The flange is secured to the FSD with fasteners that can be loosened and tightened, allowing the connector to be easily removed and reinstalled as needed for maintenance or replacement.

Inventive Principle:
Principle #15Dynamics

2Ease of manufacture

If a connector bridges over the fuel stringer duct with external sealing, then the ease of manufacture is improved, but the seal reliability deteriorates due to manufacturing tolerances requiring post-cure machining

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

Solution Approach 1:

Instead of sealing against the external surface of the FSD, the sealing surface is inverted to be on the internal surface of the hole in the FSD. The flange's outer surface engages with this internal surface, reversing the traditional sealing approach and eliminating the need for post-cure machining of the FSD external surface.

Inventive Principle:
Principle #13The other way round (Inversion)

Solution Approach 2:

The flange acts as an intermediary component that provides the sealing surface. Rather than requiring the FSD external surface to be precisely machined, the flange's inner surface against which sealing occurs can be precisely manufactured, decoupling the sealing precision requirement from the FSD manufacturing process.

Inventive Principle:
Principle #24Intermediary (Mediator)

3Reliability

If the connector sits proud of the fuel stringer duct to provide sealing surface, then the seal formation is improved, but the connector becomes liable to damage

Engineering Contradiction:
Improveseal formationVSAvoiddamage susceptibility
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The flange is inserted into a hole within the fuel stringer duct, nesting the sealing component inside the FSD structure rather than having it protrude outward. This nested arrangement protects the sealing surface from external damage while maintaining effective sealing against the internal surface of the hole.

Inventive Principle:
Principle #7Nested doll (Nesting)

Data Source

PatentEP4542100A1Connector for fuel stringer duct
Publication Date: 2025.04.23 AIRBUS OPERATIONS LTD
  • EP4542100A1 patent drawingFigure 1~2
  • EP4542100A1 patent drawingFigure 3~4
  • EP4542100A1 patent drawingFigure 5

AI summary

A connector (1) for connecting a fluid flow duct to a fuel stringer duct is disclosed. The connector (1) comprises a body (7) having an internal channel (17) for fluid passage between a first opening (9) and a second opening (13) of the body (7). A flange (19) surrounds the first opening (9), the flange (19) being configured for insertion into a hole formed in a wall of the fuel stringer duct. An outer surface (191) of the flange (19) is provided with a first sealing member (20) that surrounds the flange (19), the first sealing (20) member being configured to form a seal between the outer surface (1191) of the flange (19) and an internal surface of the hole formed in the wall of the fuel stringer duct.