Many factors will determine the temper designation you choose for your aerospace application. What is your desired balance for important factors such as machinability and strength? What specific components or parts are you looking to use the aluminum extrusion for? For 6061 aluminum extrusions in aerospace, T6 is great. If you are looking for 7075 aluminum extrusions in aerospace, consider using T6511. If choose 2024 aluminum extrusions, T3511 will be great.