Aircraft Selector Lever Failure Detection Mechanism
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Solution Overview
Problem
Current systems lack the ability to detect partial or dormant failures in aircraft controller selector levers, which can lead to unexpected flap or slat deployment, compromising aircraft safety and performance.
Innovation Solution
A selector lever mechanism with a housing, a pivotally disposed lever, a movable shaft, and detent plates with failure detection slots that allow movement only if a protrusion is missing or damaged, along with a pin release mechanism and biasing element, enabling detection of partial failures and providing redundant operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional selector lever mechanisms are used without failure detection features, then the device complexity is low, but the reliability is insufficient because partial failures cannot be detected
Solution Approach 1:
The pin is segmented into multiple protrusions (first protrusion and second protrusion) that can fail independently. The detent plate is segmented with separate slots for each protrusion and a dedicated failure detection slot. This segmentation allows the system to detect partial failures of individual protrusions while maintaining overall functionality through the remaining protrusions.
Solution Approach 2:
The failure detection slot is pre-configured in the detent plate to detect protrusion failures before they compromise safety. The slot is positioned to receive the protrusion only when it is present and properly positioned, providing advance warning of potential failures before they lead to unintended control surface movements.
2Reliability
If redundant features are added to detect partial failures, then the reliability improves, but the ease of manufacture decreases
Solution Approach 1:
The failure detection functionality is merged into the existing detent plate structure by incorporating the failure detection slot as an integrated feature rather than a separate component. The detent plate simultaneously performs its primary function of engaging protrusions and its secondary function of detecting failures through the failure detection slot, eliminating the need for additional sensors or detection mechanisms.
Solution Approach 2:
The detent plate is designed with multi-functionality, serving both as a positioning mechanism (through slots 58 and 68) and as a failure detection device (through failure detection slot 74). This universal design allows a single component to fulfill multiple roles, reducing the overall number of parts and simplifying the manufacturing process while maintaining high reliability.
3Reliability
If failure detection slots are incorporated into detent plates, then the reliability improves through early failure detection, but the device complexity increases due to additional structural features
Solution Approach 1:
The failure detection slot is strategically positioned at a specific location on the detent plate where it can effectively detect protrusion failures without requiring additional slots or features throughout the entire structure. This localized approach concentrates the detection functionality in one critical area, minimizing the increase in overall structural complexity while maintaining effective failure detection capability.
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
Enables early detection of partial failures, allowing for proactive replacement of components and preventing unintended aircraft control surface movements, thus enhancing safety and reliability.
Implementation Method 1
a biasing element operatively disposed between the shaft and the movable shaft to bias the movable shaft toward the cross-shaft
Implementation Method 2
The hand-lever 11 includes an outer end connected to the inner drive lever 50 via a torsion spring 54
Data Source
Figure 1
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AI summary
A selector lever includes a housing (16) with front and rear ends and a lever (12) with a shaft (22) pivotally disposed on a cross-shaft (20). The shaft defines a shaft axis. The lever has a top that is disposed outside of the housing. A movable shaft (24) moves substantially axially along the shaft axis. A pin (40), having first and second protrusions (50,52), is disposed adjacent to a bottom end (38) of the movable shaft. A first detent plate (44) is disposed on a first side of the movable shaft and includes at least a first slot (42) that receives the first protrusion. A second detent plate (44) is disposed on a second side of the moveable shaft and includes at least a second slot therein receiving the second protrusion. A first failure detection slot (74) is associated with the first slot, permitting movement of the first protrusion (50) therein in the absence of the second protrusion (52).