What is a key characteristic of lightening holes?

A key characteristic of lightening holes is their flange around the edge, which provides added rigidity to the structure. These holes are cut into structural components like formers and bulkheads to reduce weight without significantly compromising strength. The flanged design helps distribute stress more evenly around the hole and enhances the structural integrity of the surrounding material, making it less prone to deformation or failure.

While lightening holes may sometimes be located on the outer surface of structures, they are not limited to this position, as their primary function is weight reduction. They can come in various shapes and sizes depending on the design requirements and may not always be round or uniform. Additionally, while lightening holes are common in wing structures, they are not exclusive to them and are used in various aircraft components throughout the entire structure. The presence of the flange is what ultimately distinguishes this feature in aircraft design, supporting the overall load-bearing capability while minimizing excess weight.