Which document accompanies a major repair to return the product to service?

The correct answer is the maintenance release or FAA Form 337. When a major repair is performed on an aircraft, it is essential to document the work completed to ensure compliance with regulatory requirements. The FAA Form 337 specifically serves as a record for major repairs and alterations, which outlines the nature of the work done, the parts affected, and applies to both airframe and powerplant modifications. This form must be submitted to the FAA and is vital for the proper tracking and documentation of airworthiness.

Additionally, a maintenance release is a statement provided by the technician or mechanic who performed the repair, signifying that the aircraft is safe and ready to return to service. This is generally required to document and affirm the airworthiness of the aircraft post-repair. Thus, the combination of these documents ensures a clear and verified pathway for the aircraft's return to safe operations, complying with the regulations set forth by the FAA.