Aircraft Selector Lever Visual Failure Detection

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Solution Overview

Problem

Conventional aircraft selector levers lack an effective mechanism to detect the failure of detent pins, which can lead to increased maintenance costs and reduced safety.

Innovation Solution

A selector lever design with a shaft and pivot housing, featuring first and second detent pins with extended radial depth slots for failure detection, and a visual indicator to signal pin failure, allowing for detection of pin failure during operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional selector lever construction is used with standard detent pins and slots, then the device complexity is low, but the reliability is reduced due to inability to detect pin failure

Engineering Contradiction:
Improvefailure detection capabilityVSAvoidstructure complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The failure detection slot is pre-configured with an extended radial depth during manufacturing, creating a detection zone before actual pin failure occurs. This preliminary structural preparation enables automatic failure detection when the pin deteriorates and enters the extended zone, improving reliability without requiring complex real-time monitoring systems.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The selector lever system performs self-diagnosis through the failure detection mechanism. When a detent pin fails or deteriorates, it automatically enters the extended radial depth zone of the failure detection slot, triggering a visible indicator change. This self-detecting capability improves reliability without adding external monitoring complexity.

Inventive Principle:
Principle #25Self-service

2Reliability

If failure detection slots with extended radial depth are added, then the reliability improves through early pin failure detection, but the manufacturing precision requirements increase

Engineering Contradiction:
Improvepin failure detectionVSAvoidslot depth precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The failure detection slot is designed with a localized extended radial depth zone specifically at the critical detection position, while other portions of the slot maintain standard dimensions. This localized modification approach enables reliable pin failure detection without requiring high precision across the entire slot structure, thereby reducing overall manufacturing precision requirements.

Inventive Principle:
Principle #3Local quality

3Loss of information

If visual failure indicator is implemented, then the loss of information is reduced by providing pin status information, but the device complexity increases

Engineering Contradiction:
Improvepin status informationVSAvoidindicator mechanism complexity
Core Design Contradiction:
Loss of informationVSDevice complexity

Solution Approach 1:

The visual failure indicator is designed to automatically change state based on the physical position of the detent pin relative to the failure detection slot. When the pin enters the extended radial depth zone, the indicator mechanically or optically changes to display failure status. This self-indicating mechanism reduces information loss without requiring complex electronic monitoring or additional actuation systems.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3153405B1Visual failure indication for selector level
Publication Date: 2019.01.02 HAMILTON SUNDSTRAND CORP
  • EP3153405B1 patent drawingFigure 1
  • EP3153405B1 patent drawingFigure 2A
  • EP3153405B1 patent drawingFigure 2B

AI summary

A selector lever (1) that comprises a shaft (2) rotatably attached to a pivot (4) and arranged between two detent plates (8,10), each of the detent plates (8,10) having a plurality of slots (9,11) arranged for receiving a detent pin (12,13) located on the shaft (2). Each of the plurality of slots (9,11) on each of the two detent plates (8,10) is defined by a radial depth (D1,D2). One or more of the plurality of slots (9,11) is a failure detection slot (16,17) having an extended radial depth (E1,E2). When one of the detent pins (12,13) has failed, the opposing detent pin (12,13) is allowed to travel into the extended radial depth (E1,E2) when placed in the failure detection slot (16,17). This action reveals a failure indicator (18), providing a visual indication that one of the detent pins (12,13) has failed.