What requirement must be measured in countersinks according to the work instructions?

In aerospace applications, countersinks are critical for ensuring that fasteners sit flush with the surface of the material, which is essential for aerodynamics and structural integrity. The primary requirement that must be measured in countersinks is depth.

This measurement is vital because the depth of the countersink determines how far the fastener can be recessed into the material. If the depth is insufficient, the fastener may not be flush, which can lead to aerodynamic drag or mechanical failure due to improper load distribution. Conversely, if the countersink is too deep, it may weaken the surrounding material or compromise the joint's integrity.

While width, angle, and shape can be important in certain contexts, the depth of the countersink directly impacts functionality and assembly effectiveness. Therefore, adhering to the specified depth is critical as per the work instructions to ensure proper assembly and compliance with safety standards in aerospace manufacturing.