Aircraft Control Lever Sealing to Block Detritus Ingress

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Solution Overview

Problem

Existing control lever assemblies in aircraft systems face issues with ingress of detritus and dirt due to the movement of the control lever, which can compromise the reliability and longevity of the device.

Innovation Solution

A control lever assembly with a sealing arrangement featuring overlapping outer and inner flanges that cover the aperture between the control lever and housing, providing a non-linear ingress path for detritus while minimizing friction and maintaining a constant gap, thus preventing the entry of foreign objects.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If a control lever is made movable to control aircraft systems, then the ease of operation is improved, but the ingress of detritus and dirt worsens

Engineering Contradiction:

Improvecontrol lever movementVSAvoidingress of detritus

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent employs bellows as a flexible sealing element that extends between the movable control lever and the housing. The bellows flex to accommodate the movement of the control lever while maintaining a seal that prevents ingress of detritus and dirt into the housing.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent introduces a sealing arrangement with overlapping flanges as an intermediary barrier between the movable control lever and the housing aperture. This sealing arrangement acts as a mediator that allows control lever movement while blocking the path for detritus entry.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If a sealing arrangement is added to prevent detritus ingress, then the reliability is improved, but the device complexity worsens

Engineering Contradiction:

Improveprotection from detritusVSAvoidsealing arrangement structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent integrates the sealing function directly into the control lever assembly by incorporating overlapping flanges as part of the control lever structure itself. This merging of the sealing function with the existing control lever components avoids adding separate, complex sealing mechanisms.

Inventive Principle:

Principle #5Merging (Combining)

3Ease of operation

If the control lever moves within the housing, then the ease of operation is improved, but the manufacturing precision worsens due to maintaining constant gap

Engineering Contradiction:

Improvecontrol lever mobilityVSAvoidconstant gap maintenance

Core Design Contradiction:

Ease of operationVSManufacturing precision

Solution Approach 1:

The patent employs a dynamic sealing arrangement where the overlapping flanges can move relative to each other as the control lever moves. This dynamic configuration maintains the sealing gap automatically through the overlapping geometry, eliminating the need for precise fixed gap maintenance.

Inventive Principle:

Principle #15Dynamics

Data Source

PatentEP4147969B1Control lever assembly for controlling an aircraft system

Publication Date: 2026.03.18 RATIER FIGEAC SAS

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AI summary

A control lever assembly (10) for controlling an aircraft system, comprising: a housing (30) having an outer side (33) and an aperture (35) defined by a rim (36); and a control lever (20) extending through the aperture (35) and movable in the aperture (35); the control lever (20) having an outer cover member (61) arranged to slide over the outer side (33) of the housing (30) and cover the rim (36) throughout the range of movement of the control lever (20).