Which component is NOT typically inspected immediately before assembly?

In the context of aerospace assembly, it is crucial to ensure that all components are in optimal condition before assembly begins. Typically, fasteners, drawings, and drills are subject to inspection just prior to assembly to ensure that they meet necessary specifications and standards.

Fasteners must be checked for integrity, compatibility, and compliance with the required materials to prevent failures during operation. Drawings are inspected to confirm that they are the latest revisions and accurately depict the assembly process and required specifications. Drills must also be verified to ensure they are suitable for the materials involved and are in good working order, thereby producing the necessary precision in the assembly tasks.

Reference materials, however, are not typically inspected in the same fashion just before assembly. They serve more as guidance, such as manuals and procedures that inform the mechanics on how to perform the work rather than being components that directly participate in the assembly itself. As such, while they are critical overall to the process and ensuring that the assembly adheres to standards, they do not require the same immediate inspection as the other components. This is why the correct response identifies reference materials as the component that is not typically inspected immediately before assembly.