What type of repairs requires the completion of GACA Form 8320-1 or FAA Form 337?

The correct answer is that GACA Form 8320-1 or FAA Form 337 is required specifically for major repairs. These forms document significant modifications or major repairs that affect the aircraft's structure, performance, or characteristics.

Minor repairs, which involve routine maintenance tasks that do not appreciably alter the aircraft's structure or performance, do not necessitate the completion of these forms. Instead, minor repairs may require simpler documentation or could potentially be logged in the aircraft's maintenance records without the need for formal regulatory processes. Therefore, the scope of repairs necessitating these forms is distinctly categorized under major alterations or repairs, which aim to maintain safety and regulatory compliance for airworthiness.

Understanding the classifications between major and minor repairs is crucial, especially for maintenance personnel and operators, as it helps ensure adherence to aviation safety standards established by regulations.