Flap Actuation System Catcher Link Redundancy
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Aircraft flap actuation systems require redundant load paths to ensure fault tolerance, leading to complex assemblies, high part counts, and increased weight due to the use of pin-in-pin elements and complementary parts.
Innovation Solution
The implementation of a flap actuation system with a catcher link that remains unloaded during normal operation but is loaded upon failure to mitigate the failure, reducing the need for redundant pin-in-pin elements and complementary parts by using a single pin drive axle, first and second pivot axles, and a monolithic flap internal structure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If redundant load paths are implemented using pin-in-pin elements and complementary parts, then fault tolerance is improved, but device complexity and part count increase
Solution Approach 1:
The catcher link is pre-positioned and structurally integrated into the flap actuation system during normal operation, but remains unloaded and inactive. Upon failure of the drive link or trailing link, the catcher link automatically engages to bear the load, providing fault tolerance without requiring complex redundant mechanisms to be actively engaged during normal operation.
Solution Approach 2:
The redundant load-bearing function is extracted from the primary drive link and trailing link structure, and placed into a separate, dedicated catcher link. This allows the primary system to remain simple during normal operation, while the extracted safety function provides fault tolerance when needed.
2Reliability
If redundant load paths are implemented using pin-in-pin elements and complementary parts, then fault tolerance is improved, but aircraft weight increases
Solution Approach 1:
The catcher link is structurally integrated with the existing flap actuation system components, sharing common attachment points and structural elements. The catcher link utilizes the existing flap internal structure and support elements for its attachment, merging the safety function with the primary structure rather than adding completely separate redundant components.
Solution Approach 2:
The catcher link serves multiple functions: it provides fault tolerance by bearing load upon drive link or trailing link failure, while during normal operation it remains part of the overall structural assembly without interfering with primary function. The same structural elements serve both primary operation and safety backup functions.
3Device complexity
If the catcher link is integrated into the flap actuation system, then part count is reduced, but the system must handle load redistribution upon failure
Solution Approach 1:
The catcher link is pre-configured with appropriate structural strength and stiffness to handle the full load that may be transferred to it upon failure. The link is designed with sufficient capacity from the outset to bear the drive link or trailing link loads when failure occurs, eliminating the need for complex load-sharing mechanisms or progressive failure management.
Data Source
AI summary
A flap actuation system employed in an aircraft wing with a flap having an internal structure employs a drive link pivotally attached at a top end with a drive axle to a forward lug on the internal structure and pivotally attached at a bottom end with a first pivot axle to a flap support element. An actuator is operably coupled to the drive link intermediate the top end and bottom end. A trailing link is pivotally attached at a leading end with a second pivot axle to the flap support element and pivotally attached at a trailing end with a reaction axle to an aft fitting on the internal structure. A catcher link is pivotally attached at a bottom end to the flap support element and at a top end to an intermediate fitting engaged to the internal structure. The catcher link is unloaded in a typical operating condition and upon a failure in the drive link, first pivot axle, drive axle, forward lug, trailing link, second pivot axle, reaction axle or aft fitting a load is induced on the catcher link to accommodate the failure condition.