Aircraft Landing Gear Door Unlock Sequencing for Latch Failure Detection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing aircraft landing gear hatch locking systems face challenges in ensuring structural integrity and reliability due to classification as a principal structural element, necessitating stringent design, material, and inspection requirements, which are not adequately addressed by current hydromechanical or electromechanical actuators.
Innovation Solution
A method and device utilizing a dual latching system with two latching boxes and actuators, combined with a control unit and proximity sensors, to staggered unlock sequences and detect hatch opening, ensuring functional integrity of each latching mechanism during deployment and retraction cycles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a single latching box is used to lock the hatch, then the device complexity is reduced, but the reliability is compromised because a single failure can lead to untimely deployment
Solution Approach 1:
The single latching box is segmented into two separate latching boxes (first latching box and second latching box), each capable of independently locking the hatch. This segmentation allows the system to maintain reliability through redundancy while managing complexity through modular design, where each latching box functions as an independent unit.
2Reliability
If stringent design and material requirements are imposed on the latching box to ensure structural integrity, then the reliability is improved, but the ease of manufacture deteriorates
Solution Approach 1:
By dividing the latching system into two separate latching boxes, each unit can be manufactured using standard materials and processes without requiring the entire assembly to meet extreme structural requirements. This segmentation allows for easier manufacturing of individual components while maintaining overall system integrity through the redundant configuration.
3Reliability
If visual inspection methods are implemented to detect anomalies in the latching box, then the reliability is improved, but the ease of operation deteriorates due to additional inspection requirements
Solution Approach 1:
The latching system is divided into two accessible latching boxes that can be individually inspected. This segmentation allows maintenance personnel to perform focused visual inspections on each unit separately, making the inspection process more manageable and less cumbersome than inspecting a single complex integrated system.
4Reliability
If a staggered unlocking sequence is implemented to test latching mechanism functionality, then the reliability is improved, but the loss of time increases due to waiting periods
Solution Approach 1:
The control unit is programmed with a predetermined staggered unlocking sequence that activates the first unlocking actuator, waits for a predetermined time period to allow detection of hatch movement, then activates the second unlocking actuator. This preliminary programming of the sequence minimizes the actual time loss by eliminating manual intervention and optimization opportunities.
5Reliability
If detection means are added to detect hatch opening during the waiting period, then the reliability is improved through failure detection, but the device complexity increases
Solution Approach 1:
Detection means are incorporated to monitor whether the hatch begins to open during the predetermined waiting period after the first latching box is unlocked. This feedback mechanism provides information about the functional integrity of the second latching box, allowing the system to detect potential failures. The feedback is integrated into the existing control unit, minimizing additional complexity.
Data Source
Figure 1
Figure 2
Figure 3A
AI summary
A method for unlocking a door (20) of an aircraft landing gear movably mounted between an open position and a closed position, the door (20) being associated with attachment means comprising a first attachment housing (23.1) and a second attachment housing (23.2) arranged to individually lock the door (20) in the closed position, a first unlocking actuator (22.1) and a second unlocking actuator (22.2) arranged to respectively control the first attachment housing (23.1) and the second attachment housing (23.2) with a view to deactivating them, and means for detecting (40) the door in the closed position, the method comprising the step of sequentially deactivating the attachment housing in order to detect whether the last attachment housing has failed to deactivate. A device and an aircraft using said method.