Which document must be referenced for major alterations on aircraft?

The Aircraft Maintenance Manual is the correct document to reference for major alterations on aircraft because it provides the specific procedures, instructions, and guidelines necessary for maintenance and alterations. This manual is crucial for ensuring that any modifications performed on an aircraft adhere to safety standards and regulatory requirements, thus maintaining the aircraft's airworthiness status. It typically includes information about troubleshooting, repair, and replacement of components as well as any alterations that may affect the operation of the aircraft.

In contrast, Technical Standard Orders serve as a set of criteria for certain types of equipment and parts, providing standards for quality and performance rather than guidance on alterations or maintenance procedures. The FAA Certification Guide is focused on the certification process for new aircraft or aircraft modifications rather than detailing how to perform the alterations themselves. The Airworthiness Guide primarily provides information on maintaining aircraft airworthiness but does not specifically address the procedures for performing major alterations. Thus, the Aircraft Maintenance Manual stands out as the essential reference for ensuring that major alterations are performed correctly and safely.