When replacing rivets with AN-3 bolts on a .091-inch thick aluminum repair, how many bolts should be used per inch wide?

The correct choice indicates that for a .091-inch thick aluminum repair, approximately 2.4 AN-3 bolts are required per inch of width. This calculation stems from the established standards for replacing rivets with bolts, where the strength and spacing requirements dictate how many fasteners are necessary to maintain structural integrity.

In aerospace applications, especially when dealing with repairs, it is crucial to ensure that the chosen fastener configuration can support the loads acting on the structure. The conversion from rivets to bolts involves understanding the criteria for spacing, which often depends on the thickness of the material being repaired and the specific rivet or bolt type being used.

By establishing a requirement of around 2.4 bolts per inch, engineers accommodate for potential variations in load distribution and ensure that the repair will be structurally sound. This standard also reflects engineering practices that balance ease of maintenance with the requirement for safety and performance in flight operations.