Major alteration Regulation
Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications— (1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or (2) That is not done according to accepted practices or cannot be done by elementary operations.
Also defined in 3 more sources
An alteration not listed in the aircraft, aircraft engine, or propeller specifications: (1) that might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or (2) that is not done according to accepted practices or cannot be done by elementary operations.
Guidance: Aviation Maintenance Technician Handbook — General, p. G-6; Aircraft Weight and Balance Handbook, p. G-3
An alteration not listed in the aircraft, aircraft engine, or propeller specifications. It is one that might appreciably affect weight, balance, structural strength performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness, or that cannot be made with elementary operations.
Guidance: Aviation Maintenance Technician Handbook — Airframe, p. G-22
An alteration not listed in the aircraft, aircraft engine, or propeller specifications that might appreciably affect weight, balance, structural strength, powerplant operation, flight characteristics, or other qualities affecting airworthiness; an alteration not done according to accepted practices, or one that cannot be done by elementary operations.
Guidance: Aviation Maintenance Technician Handbook — Powerplant, p. G-17
Taught in GEN-I Quick reference, GEN-A Concepts, GEN-I Concepts, GEN-I Procedures.