Plain English Meaning
A short list of small, routine maintenance jobs that a pilot-owner is legally allowed to do on their own aircraft, instead of paying a mechanic.
Full Definition
A specific category of simple, minor maintenance work that the FAA permits a certificated pilot who owns or operates an aircraft to perform on that aircraft, without requiring a certificated mechanic. The allowed tasks are listed in 14 CFR Part 43, Appendix A, and include items such as replacing landing gear tires, servicing landing gear wheel bearings, replacing safety belts, and changing engine oil. It does not include major repairs or major alterations.