14 CFR § 145.205

A certificated repair station that performs maintenance, preventive maintenance, or alterations for an air carrier or commercial operator that has a continuous airworthiness maintenance program under part 121 or part 135 must follow the air carrier's or commercial operator's program and applicable sections of its maintenance manual.

A certificated repair station that performs inspections for a certificate holder conducting operations under part 125 must follow the operator's FAA-approved inspection program.

A certificated repair station that performs maintenance, preventive maintenance, or alterations for a foreign air carrier or foreign person operating a U.S.-registered aircraft under part 129 must follow the operator's FAA-approved maintenance program.

The FAA may grant approval for a certificated repair station to perform line maintenance for an air carrier certificated under part 121 or part 135 of this chapter, or a foreign air carrier or foreign person operating a U.S.-registered aircraft in common carriage under part 129 of this chapter on any aircraft of that air carrier or person, provided-

The certificated repair station performs such line maintenance in accordance with the operator's manual, if applicable, and approved maintenance program;

The certificated repair station has the necessary equipment, trained personnel, and technical data to perform such line maintenance; and

The certificated repair station's operations specifications include an authorization to perform line maintenance.