Fastener Locking Assembly for Aircraft Anti-Rotation Joints
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Solution Overview
Problem
Aircraft fasteners with drive features in their threaded tails and nuts experience unwanted relative rotation, which existing torque values and sealants or adhesives may not adequately prevent, posing a challenge in securing aircraft components without compromising aerodynamic surfaces.
Innovation Solution
An assembly comprising a nut plate and fastener plate, with locking members and drive feature engagement members, couples the nut and fastener to prevent relative rotation, and an optional base plate secures the assembly to the workpiece, using aligned holes and locking fasteners for stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If torque values are increased to prevent rotation of fasteners and nuts, then the security of the fastening is improved, but the risk of damaging the wing skin panel or aircraft superstructure increases
Solution Approach 1:
The patent introduces a locking mechanism as an intermediary device between the fastener and nut. This locking mechanism prevents relative rotation by mechanically interlocking the two components, thereby eliminating the need to increase torque values that could damage the aircraft structure. The locking mechanism acts as a mediator that provides rotational security without transmitting excessive forces to the wing skin panel or superstructure.
2Reliability
If sealants or adhesives are used to enhance the security of fasteners and nuts, then the prevention of relative rotation is improved, but the suitability for use under aircraft conditions may be compromised
Solution Approach 1:
The patent replaces the chemical bonding mechanism of sealants and adhesives with a mechanical locking system. The locking mechanism uses physical interlocking features (such as protrusions and recesses, or threaded connections) to prevent relative rotation between the fastener and nut. This mechanical approach is more reliable than adhesives under aircraft conditions, which may involve extreme temperatures, vibrations, and exposure to various chemicals that could degrade adhesive bonds.
3Reliability
If a locking mechanism is added to prevent relative rotation of fasteners and nuts, then the security against rotation is improved, but the complexity of the fastening system increases
Solution Approach 1:
The patent merges the locking function with the existing fastener and nut components. Rather than adding a completely separate locking device, the locking features are integrated into the fastener-nut assembly itself. For example, the fastener may include integrated locking protrusions that engage with corresponding features on the nut, or the locking mechanism may be incorporated as part of the fastener head or tail. This integration approach provides rotational security while minimizing the increase in system complexity.
Data Source
AI summary
An assembly is provided for preventing the relative rotation of a fastener and a nut by way of a nut plate that engages with a drive feature of the nut and a fastener plate that engages with a drive feature of the fastener. The nut plate and fastener plate are secured together to prevent their relative rotation. A base plate is secured to a workpiece in which the nut and fastener are located that is further secured to the nut plate and the fastener plate to prevent the relative rotation of the fastener and nut with respect to the workpiece. The plates have locking members that extend away from the fastener and can be secured together e.g. by drilling and fastening.