What does a cross or asterisk marking on an aircraft bolt indicate?

A cross or asterisk marking on an aircraft bolt is a standard designation used to indicate the material composition of the bolt. Specifically, this marking typically signifies that the bolt is made of standard steel, which is widely used in various aircraft applications due to its strength and availability. The marking helps maintenance crews and engineers quickly identify the type of bolt used, ensuring that repairs and replacements can maintain material consistency and safety standards within the aircraft system.

The other options suggest specific material compositions or qualities that are not indicated by a cross or asterisk marking. For example, while titanium is known for its lightweight and strength, it would not typically be marked in this manner. Similarly, compliance with safety standards is usually denoted through different labeling methods or certifications, and enhanced corrosion resistance would be indicated by specific coatings or treatments, rather than by a simple cross or asterisk. Thus, the correct interpretation aligns with standard steel manufacture, ensuring clarity in maintenance and replacement operations.