An aircraft assembly having a titanium rod comprising a first threaded portion, and a titanium nut comprising a second threaded portion conforming with the first threaded portion for mating engagement with it. One of the first and second threaded portions defines a male thread and the other one of the first and second threaded portions defines a female thread such that the nut can be wound in threading engagement along the rod. A threaded insert formed from a first metal of different hardness in comparison to titanium is coupled to the rod or the nut to define the first threaded portion or the second threaded portion respectively such that one of the first and second threaded portions is formed from titanium and the other one of the first and second threaded portions is formed from the first metal.