Which fastener property is most critical for maintaining structural integrity in an aircraft?

The strength and load capacity of a fastener are vital for maintaining the structural integrity of an aircraft because these properties determine how well the fastener can secure components together and withstand the forces experienced during flight. Aircraft undergo numerous stress factors including tension, compression, shear, and bending loads, all of which can impact both the joints and the overall structure.

A fastener that has inadequate strength or load capacity could fail under these conditions, potentially leading to catastrophic structural failure. Thus, ensuring that fasteners are appropriately rated for the specific loads they will encounter is crucial for safety and reliability.

While the other factors, such as appearance, weight, and cost, may have relevance to certain aspects of design and selection, they do not directly influence the ability of the fastener to maintain the aircraft's structural integrity under load. Therefore, the focus on strength and load capacity directly correlates to ensuring that the aircraft remains safe and operational during its service life.