What are the three common head styles of jo-bolts?

• A. Flat, rounded, and recessed
• B. Flush, hex, and hex-millable
• C. Spherical, countersunk, and rounded
• D. Flat, dome, and slotted

Answer: (B)

The three common head styles of jo-bolts, which are often used in aviation and structural applications for their effectiveness in providing a secure fastening, are flush, hex, and hex-millable.

The flush head design allows the bolt head to sit level with the surface of the material, reducing the risk of snagging and permitting a smooth finish, which is particularly advantageous in aerodynamic applications. The hex head design provides a grip for tools, enabling a more secure fastening and making it easier to apply the necessary torque during installation. The hex-millable head style allows for machining if necessary, adapting the bolt for specific applications where modifications may be required after installation.

These head styles are quite distinct in their functionalities and uses, which is why option B is the most accurate representation of common jo-bolt head styles utilized in structural applications.