After visually inspecting every countersink, what should be done with every 5th and 10th countersink?

Measuring every 5th and 10th countersink with a Federal gauge is essential to ensure that they meet the specified standards for depth and diameter. This type of measurement confirms that the countersink has been correctly machined to accommodate the fastener being used, which is crucial for maintaining the structural integrity of the assembly.

The Federal gauge provides a precise way to assess whether the countersink dimensions fall within tolerance limits. Variations in countersink depth or width can lead to issues such as improper seating of rivets or screws, which might compromise the load distribution and overall performance of the aerospace component. Thus, using the gauge at these specified intervals helps maintain quality control throughout the assembly process, ensuring that any deviations are identified and corrected promptly.