Aircraft Thrust Reacting Device with Backup Pin
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Solution Overview
Problem
The existing design of the device for reacting thrust forces in aircraft propulsion assemblies leads to out-of-plane forces that can cause premature wear of ball joint rings, and there is a need to modify this design to address this issue while maintaining a horizontally mounted connection pin and ensuring secondary force paths in case of component failure.
Innovation Solution
The proposed aircraft propulsion assembly includes a device for reacting thrust forces with a main fitting, a pivotable spreader, and two rods on either side of the median vertical plane, each rod having a front end articulated to the turbomachine and a rear end articulated to the spreader. This design incorporates a secondary fitting with a backup connection pin for secondary force transfer in case of primary path failure.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the rods are mounted by a horizontally connected pin to optimize compactness and access, then the compactness and operator access are improved, but out-of-plane forces are generated that cause premature wear of ball joint rings
Solution Approach 1:
A secondary connection pin is introduced as an intermediary element to share the load and redirect out-of-plane forces. The secondary pin is positioned offset from the mean plane of the rods, creating a geometric arrangement that converts harmful out-of-plane forces into beneficial in-plane force components that are transmitted to the structure rather than concentrated on the ball joint rings.
Solution Approach 2:
The solution moves from a single-plane (2D) connection to a multi-dimensional (3D) arrangement by positioning the secondary connection pin out of the mean plane of the rods. This spatial arrangement in the third dimension allows the system to simultaneously maintain horizontal mounting for accessibility while redistributing forces to prevent premature wear.
2Volume of moving object
If the connection pin is mounted horizontally to optimize compactness, then the compactness is improved, but out-of-plane forces are generated that cause premature wear
Solution Approach 1:
The secondary connection pin acts as a mediator that redistributes forces without increasing the overall footprint of the device. By positioning it offset from the mean plane, it creates a force redistribution mechanism that maintains compactness while eliminating the harmful out-of-plane force components that lead to wear.
Solution Approach 2:
The secondary pin is positioned in the vertical dimension (out of the horizontal mean plane), allowing force redistribution in three dimensions without increasing the horizontal footprint. This enables the device to maintain its compact form factor while solving the wear problem through spatial force management.
3Reliability
If the design is modified to eliminate out-of-plane forces, then the reliability is improved, but the horizontal mounting of connection pin may be compromised
Solution Approach 1:
The secondary connection pin serves as a mediator that enables both objectives simultaneously - it eliminates out-of-plane forces through its offset positioning while the primary horizontal connection pin maintains operator accessibility. The intermediary element distributes forces in a way that preserves the benefits of horizontal mounting.
Solution Approach 2:
By introducing the secondary pin in the vertical dimension (out of plane), the solution resolves the force distribution problem without altering the horizontal mounting arrangement. This allows operator access to remain unchanged while reliability is improved through three-dimensional force management.
Data Source
AI summary
A propulsion assembly for an aircraft, having a turbomachine, a pylon, and a device for reacting thrust forces having a main fitting, a spreader pivoting on the main fitting and having an opening, two rods articulated to the turbomachine and to the spreader, a secondary fitting fastened beneath the pylon and having a secondary female clevis constituted of two secondary arms passed through by holes of oblong shape and aligned along a secondary axis (R2), wherein the spreader is housed in the secondary female clevis of the secondary fitting, wherein the opening is coaxial with the secondary axis (R2), and a backup connection pin inserted with a tight fit into the opening and with clearance into the holes. Also an aircraft with such a propulsion assembly.