Servicing and maintenance facilities

Airlines operating under Part 121 domestic or flag operations must demonstrate they have adequate maintenance infrastructure throughout their route system. This means showing the FAA that qualified maintenance personnel, proper facilities, equipment, spare parts, supplies, and materials are available at necessary points along their routes.

The regulation doesn't require maintenance capability at every airport, only at points "necessary" for proper servicing and maintenance. This allows airlines flexibility in their maintenance planning while ensuring they can address mechanical issues wherever they reasonably might occur during operations.

In practice, this means airlines must have a network of maintenance stations or contracts with qualified service providers so aircraft don't become stranded without proper maintenance support. The airline must prove this capability exists before receiving or maintaining their operating certificate. This requirement helps ensure aircraft remain airworthy throughout their scheduled operations and that mechanical issues can be addressed promptly and professionally.

*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.*