Aircraft Engine Shear Pin Immobilization via Rear-Access Fork System
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Solution Overview
Problem
In aircraft engine attachments, particularly for ultrahigh bypass ratio engines, accessing the front of the attachment body is challenging due to the need to immobilize shear pins in translation, which requires recesses on the fixing lugs and attachment body, making it difficult to mount and maintain the engine units.
Innovation Solution
The introduction of a cylindrical shear pin with a flange and a fork-type system that includes a groove and a removable stop, allowing immobilization from the primary structure, enabling the shear pin to be mounted and secured without needing access to the front of the attachment body, utilizing a first and second hole configuration and a fork connected via a removable link to immobilize the shear pin in translation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a removable stop is placed at the second end of the shear pin to prevent exit, then the shear pin can be immobilized in translation, but recesses must be created on the fixing lugs and attachment body requiring access to the front of the attachment body which is impossible in certain cases
Solution Approach 1:
Instead of preventing shear pin exit from the front of the attachment body, the invention inverts the approach by preventing entry from the rear. The fixing lug includes a recess with a bottom facing the rear of the attachment body, and a stop element is positioned at this bottom to block the shear pin from being inserted or removed from the rear side, eliminating the need for front access.
Solution Approach 2:
The invention transitions from a front-access-based immobilization system to a rear-access-based system. By positioning the stop element at the bottom of the recess on the fixing lug (rear side), the shear pin immobilization is achieved through a dimensional shift in access direction, allowing operation from the rear rather than requiring front access.
2Reliability
If recesses are created on the fixing lugs and attachment body for shear pin insertion and stop placement, then shear pin immobilization is achieved, but the device complexity increases due to additional structural features
Solution Approach 1:
The invention merges the stop element with the fixing lug structure itself. The stop element is positioned at the bottom of the recess on the fixing lug, combining the functions of the fixing lug (mechanical connection) and the stop element (immobilization) into a single integrated structural feature, thereby reducing overall device complexity.
Solution Approach 2:
The recess on the fixing lum serves multiple functions: it accommodates the shear pin, provides a location for the stop element, and structurally connects to the primary structure. This multi-functional design reduces the need for separate dedicated components, simplifying the overall structure while maintaining reliable shear pin immobilization.
Data Source
AI summary
An aircraft engine attachment connecting an attachment body and a primary structure of an aircraft pylon, the engine attachment comprising a shear pin immobilized in translation by a first immobilization system that comprises a shoulder and a removable stop that are integral with the primary structure, between which a flange of the shear pin is immobilized, and a second immobilization system that comprises, first, a groove positioned in an extension of the shear pin and, second, a fork connected to the primary structure via at least one removable link and interacting during operation with the groove in such a manner as to immobilize the shear pin in translation.