Strongback Skin Tensioning for Aircraft Fuselage Frame Assembly

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Solution Overview

Problem

The current assembly process for composite panels in aircraft fuselage construction requires significant manpower, involves multiple steps of attaching and reattaching frames, and necessitates the use of numerous fasteners, which is inefficient and labor-intensive.

Innovation Solution

A device and method for assembling a skin and frame of an aircraft fuselage, which includes a support platform with arches and a strongback that applies tension to the skin, reducing the need for manual labor and multiple fastener installations by aligning the skin, attaching the frame at limited points, engaging the strongback, and applying tension to the skin.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If multiple technicians manually attach the frame with multiple fasteners, then the frame can be securely attached to the skin, but the assembly process becomes labor-intensive and time-consuming

Engineering Contradiction:

Improveframe attachment securityVSAvoidassembly efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent replaces manual mechanical fastening operations with a tensioning device that applies controlled tension forces to the skin, causing it to conform to the frame and eliminating the need for multiple manual fastener installations. The tensioning device mechanically substitutes for multiple technicians performing repetitive fastening operations.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The skin is pre-tensioned before final frame attachment, allowing the frame to be secured at limited points. The tensioning device applies force in advance to position the skin correctly, reducing subsequent assembly steps and fastener requirements.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If technicians check tie foot locations and door surround frame for gaps, then assembly precision can be ensured, but the process requires additional time and manual inspection steps

Engineering Contradiction:

Improvegap detection accuracyVSAvoidinspection time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The tensioning device replaces manual gap inspection with automated tension application. By applying controlled tension to the skin, the device automatically positions the skin against the frame, eliminating gaps without requiring manual checking. The mechanical tensioning process inherently ensures proper positioning.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The skin itself serves as the indicator of proper positioning. When the tensioning device applies force, the skin naturally conforms to the frame shape, making the skin's position self-evident and eliminating the need for separate inspection steps by technicians.

Inventive Principle:

Principle #25Self-service

3Manufacturing precision

If frames and door surrounds are removed and re-installed multiple times, then proper fit and gap verification can be achieved, but the assembly process becomes complex and time-consuming

Engineering Contradiction:

Improveframe fit verificationVSAvoidassembly process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The skin is pre-tensioned to its final position before frame attachment, ensuring proper fit from the beginning. This preliminary positioning eliminates the need for multiple removal and reinstallation cycles, as the skin is already in its correct position when the frame is permanently attached.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent combines the positioning and attachment operations into a single integrated process. The tensioning device simultaneously positions the skin and enables frame attachment at limited points, merging multiple separate operations (positioning, verification, attachment) into one coordinated action.

Inventive Principle:

Principle #5Merging (Combining)

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

This solution significantly reduces the manpower required for assembly, minimizes the number of fasteners needed, and streamlines the process by applying tension to the skin while the frame is engaged, thereby improving efficiency and reducing assembly time.

Implementation Method 1

First and second tension devices apply tension to the skin at the strongback

Methodology Applied

Scientific EffectTension: Tension

Data Source

PatentEP4273050B1Method and apparatus for the application of frame to fuselage pull-up force via fuselage skin waterline tensioning

Publication Date: 2025.06.04 THE BOEING CO

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AI summary

A device to assemble a skin (91) and a frame (92) of an aircraft fuselage (101). The device includes first and second brace members (21) that extend along opposing sides (93) of a gap (23). Arches (25) are spaced apart and fixedly connected to the first and second brace members (21) and that extend across the gap (23). A strongback (60) is attached to and movable along the first and second brace members (21) with the strongback (60) having a curved shape that matches the plurality of arches (25). The strongback (60) includes clamps (48, 75, 76) configured to engage with the frame (92). First and second tension devices apply tension to the skin (91) at the strongback (60). A corresponding assembly method is disclosed.