What is the function of a filler in the fuselage assembly?

In fuselage assembly, the function of a filler is primarily to reinforce the joint between the stringers. Stringers are long, longitudinal members that provide structural support to the aircraft’s skin, and they play a crucial role in maintaining the integrity of the airframe. The filler material, which is often used to bridge the gaps between the stringers, enhances strength and stability at these critical junctions. This reinforcement helps distribute loads more effectively and provides additional support during the aircraft's operation, particularly under stress and during flight conditions.

The usage of filler also contributes to creating a more aerodynamic surface by ensuring that the skin and stringers are properly aligned and provides a smoother transition. In addition, the filling can help protect against environmental factors such as moisture and corrosion, depending on the materials used. Therefore, the correct identification of the filler’s primary role in reinforcing joints underscores its importance in maintaining structural integrity and overall performance of the fuselage.