Name two common thread standards used in aircraft hardware and indicate how you determine which to use.

Name two common thread standards used in aircraft hardware and indicate how you determine which to use.

• A. Whitworth and metric; selection based on color.
• B. Unified and metric; selection based on operator preference.
• C. Square threads and trapezoidal threads; selection based on weight.
• D. UNC/UNF (inch-based) and metric threads; selection based on the hardware specification and thread standard of the assembly.

Answer: (D)