Why is it important to inspect the underlying structure before applying fabric?

Inspecting the underlying structure before applying fabric is crucial primarily to check for corrosion or damage. This step ensures the integrity and safety of the aircraft. Corrosion can weaken structural components, and any existing damage could compromise the aircraft’s performance or safety during operation. By identifying these issues prior to fabric application, necessary repairs can be made, ensuring that the covering material adheres properly to a stable and sound structure. This inspection not only contributes to the longevity of the fabric covering but also enhances overall safety and reliability in flight operations.