Major Alteration:
An alteration not listed in the aircraft, aircraft engine, or propeller specifications, that:
1) Might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or
2) Is not done according to accepted practices or cannot be done by elementary operations.
Major Repair:
A repair that fits one or more of the following:
1) Might appreciably affect airworthiness by changing weight, balance, structural strength, performance, powerplant operation, or flight characteristics if improperly done; or
2)Is not done according to accepted practices or cannot be done by elementary operations.