Which statement is true regarding certificated mechanics performing repairs to instruments?

The statement that only GACA-approved stations can perform repairs is accurate because it emphasizes the regulatory requirements governing maintenance activities in the aviation sector. In many jurisdictions, including those regulated by the General Authority of Civil Aviation (GACA), repairs to aircraft instruments must typically be carried out by facilities that have met specific standards and have been granted approval by the relevant aviation authority. These approved stations are subject to rigorous oversight to ensure that they adhere to safety and quality standards in maintenance practices.

This aligns with the principles of air safety, as repairs must be conducted under comprehensive guidelines to prevent any potential hazards. Certificated mechanics may be skilled and knowledgeable, but the authority to perform certain repairs, especially those that significantly affect aircraft instruments, often lies exclusively with approved maintenance organizations.

This context clarifies why the other options may not hold true: minor repairs may have restrictions based on the complexity and regulatory framework, there are specific conditions under which mechanics can approve work for return to service, and not all mechanics require an airframe rating to work on instruments, as it depends on the specific regulations and the type of repair needed.