Aircraft Lock Indicator With Internal Visual Window

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Solution Overview

Problem

Existing visual indication systems for aircraft nacelle hoods are prone to aerodynamic disturbances, weight increase, and malfunction, making it difficult to determine the locked or unlocked state of the hoods.

Innovation Solution

A visual indication system with a transparent wall and internal indicator that moves between visible and invisible positions based on the locking device's state, eliminating the need for external slots and reducing aerodynamic disturbances.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a slot is provided in the outer wall to allow the indication element to move between retracted and extended positions, then visual indication of the locking state is achieved, but aerodynamic disturbances occur and the wall requires reinforcement which increases the mass of the hood

Engineering Contradiction:
Improvevisual indication reliabilityVSAvoidhood mass
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The indication element is extracted from the external environment and placed entirely within the interior of the hood. The indicator moves between visible and hidden positions relative to a transparent section of the wall, eliminating the need for external slots while maintaining visual indication functionality.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The indication element is nested within the hood's interior space, utilizing the existing structural volume. The indicator is positioned inside the hood and moves relative to a transparent wall section, allowing visual indication without penetrating the external skin.

Inventive Principle:
Principle #7Nested doll (Nesting)

2Ease of operation

If a rigid and movable indication element is used that moves between retracted and extended positions through a slot, then the locking state can be indicated, but the slot generates aerodynamic disturbances and requires wall reinforcement

Engineering Contradiction:
Improvevisual detection easeVSAvoidaerodynamic disturbances
Core Design Contradiction:
Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The indication mechanism is extracted from the external aerodynamic flow and relocated to the interior of the hood. The indicator interacts with a transparent wall section from the inside, completely eliminating slots in the outer skin and associated aerodynamic disturbances.

Inventive Principle:
Principle #2Taking out (Extraction)

3Reliability

If electronic sensors or indicator lights are used to indicate the locking device state, then visual indication is provided, but the risk of malfunction increases

Engineering Contradiction:
Improvevisual indication reliabilityVSAvoidsystem complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The locking device itself serves the dual function of both securing the hood and indicating its state. The locking element's position directly controls the visibility of the indicator, eliminating the need for separate sensors, electronics, or power systems.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The physical position of the locking element is directly copied to the visual domain through the indicator's visible/hidden states. The indicator provides a direct mechanical analog of the locking state without requiring electronic signal conversion.

Inventive Principle:
Principle #26Copying

Data Source

PatentEP4403458B1Aircraft comprising a locking device and a system for visually indicating the state of said locking device
Publication Date: 2026.03.11 AIRBUS OPERATIONS (SAS)
  • EP4403458B1 patent drawingFigure 1~3
  • EP4403458B1 patent drawingFigure 4~5
  • EP4403458B1 patent drawingFigure 6~8

AI summary

The invention relates to an aircraft comprising at least one visual indication system (50) for the locked or unlocked state of a locking device. This visual indication system (50) comprises: - at least one opening (52) through a wall (46), - a transparent wall (54) covering the opening (52) and allowing the interior of the aircraft to be seen from the exterior, - at least one indicator (56) movable between first and second positions depending respectively on the locked or unlocked state of the locking device, said indicator (56) being positioned in the interior of the aircraft and comprising at least one zone (Z1) visible through the transparent wall (54) from the exterior of the aircraft when the indicator (56) is in the first position, the zone (Z1) not being visible when the indicator (56) is in the second position. This solution makes it possible to reduce the aircraft's mass and aerodynamic disturbances.