What is used to record and approve for return to service major alterations and repairs?

• A. FAA form 337
• B. logbook entry
• C. airworthiness certificate
• D. service bulletin

Answer: (A)

For major alterations and repairs, the official way to record what was done and to authorize the aircraft to return to service is FAA Form 337. This form captures the specifics of the work, ties it to the approved data (like an STC, field approval, or other approved data), and includes a statement that the work complies with the applicable regulations and is safe to return to service. It must be completed by the person performing the work, signed by the mechanic and the supervising inspector or repair station, and then submitted to the FAA with a copy kept in the aircraft’s records. Only after this form has been reviewed and approved does the aircraft regain its standing to fly.

A logbook entry records maintenance activity, but it does not serve as the official approval for return to service for major alterations or repairs. An airworthiness certificate is the ongoing proof of eligibility to fly, not the record of a specific alteration or its approval. A service bulletin is a manufacturer’s recommendation or instruction, not the official authorization for returning the aircraft to service after a major alteration or repair.