What characteristic is essential for fasteners used in aircraft assembly?

In aircraft assembly, fasteners must exhibit resistance to fatigue, making this characteristic essential. Aircraft are subjected to various operational stresses, such as vibration, thermal cycling, and mechanical loads, which can lead to fatigue failure over time. Fatigue resistance ensures that the fasteners maintain their integrity and load-bearing capability throughout the aircraft's operational life.

Fasteners that are not resistant to fatigue can develop cracks or fail under repeated loading conditions, potentially compromising the structural integrity of the aircraft. This is particularly critical given the safety requirements in aviation, where even a small failure can have serious consequences.

Other characteristics such as ease of installation, conductivity, and cost may be important in certain contexts but do not match the critical necessity of resistance to fatigue in ensuring the long-term reliability and safety of aircraft structures.