What is the standard aviation countersink angle?

The standard aviation countersink angle is 100 degrees. This angle is specifically designed to accommodate the heads of countersunk screws and rivets used in aircraft construction and repair. The 100-degree angle permits the fasteners to sit flush with the surface of the material, thereby reducing aerodynamic drag and preventing snagging or damage during operations. This flush fit is crucial in maintaining the integrity and performance of the aircraft structure.

The choice of an angle other than 100 degrees, such as 90, 110, or 120 degrees, would not provide the optimal seating for these fasteners, potentially leading to uneven surfaces, increased turbulence, and even structural weaknesses. The adherence to a standard angle also helps ensure compatibility and ease of assembly within the aviation industry, making it a critical specification for both safety and performance.