Final answer:
A mechanic can find a list of major alterations for FAA certificated aircraft in the STC database, ACO, and FSDO.
Step-by-step explanation:
A mechanic can find a list of major alterations that have been made and approved for FAA certificated aircraft in the FAA's database known as the Supplemental Type Certificate (STC) database. This database contains information on alterations and modifications to aircraft that have been approved by the FAA.
In addition to the STC database, mechanics can also refer to the FAA's Aircraft Certification Office (ACO) or the Flight Standards District Office (FSDO) for information on major alterations. These offices can provide guidance and resources for finding approved alterations for specific aircraft models.
When searching for approved alterations, mechanics should use the specific make, model, and registration number of the aircraft to ensure they find the most accurate and relevant information.