Applicability

This regulation sets the scope for Part 121's maintenance requirements. It establishes that all air carriers operating under Part 121 must follow the maintenance, preventive maintenance, and alteration rules in this subpart.

However, it includes an important exception: the FAA can authorize a carrier to use aircraft parts that were maintained, altered, or inspected by non-certificated personnel working outside the United States. Normally, only FAA-certificated mechanics can perform this work, but this provision recognizes the practical reality of international operations where U.S. mechanics may not be available.

If granted this deviation through amended operations specifications, the carrier must actively oversee these foreign facilities and their practices to ensure all work meets the standards in the carrier's maintenance manual. This allows operational flexibility while maintaining safety oversight through the carrier's quality control program.

*This is a plain-English summary for study only. The official 14 CFR text on this page is controlling — always read the current regulation and consult a CFI.*