14 CFR § 135.426

A certificate holder may arrange with another person for the performance of maintenance, preventive maintenance, and alterations as authorized in § 135.437(a) only if the certificate holder has met all the requirements in this section. For purposes of this section—

A maintenance provider is any person who performs maintenance, preventive maintenance, or an alteration for a certificate holder other than a person who is trained by and employed directly by that certificate holder.

Covered work means any of the following:

Essential maintenance that could result in a failure, malfunction, or defect endangering the safe operation of an aircraft if not performed properly or if improper parts or materials are used;

Regularly scheduled maintenance; or

A required inspection item on an aircraft.

Directly in charge means having responsibility for covered work performed by a maintenance provider. A representative of the certificate holder directly in charge of covered work does not need to physically observe and direct each maintenance provider constantly, but must be available for consultation on matters requiring instruction or decision.

Each certificate holder must be directly in charge of all covered work done for it by a maintenance provider.

Each maintenance provider must perform all covered work in accordance with the certificate holder's maintenance manual.

No maintenance provider may perform covered work unless that work is carried out under the supervision and control of the certificate holder.

Each certificate holder who contracts for maintenance, preventive maintenance, or alterations must develop and implement policies, procedures, methods, and instructions for the accomplishment of all contracted maintenance, preventive maintenance, and alterations. These policies, procedures, methods, and instructions must provide for the maintenance, preventive maintenance, and alterations to be performed in accordance with the certificate holder's maintenance program and maintenance manual.

Each certificate holder who contracts for maintenance, preventive maintenance, or alterations must ensure that its system for the continuing analysis and surveillance of the maintenance, preventive maintenance, and alterations carried out by a maintenance provider, as required by § 135.431(a), contains procedures for oversight of all contracted covered work.

The policies, procedures, methods, and instructions required by paragraphs (e) and (f) of this section must be acceptable to the FAA and included in the certificate holder's maintenance manual, as required by § 135.427(b)(10).

Each certificate holder who contracts for maintenance, preventive maintenance, or alterations must provide to its responsible Flight Standards office, in a format acceptable to the FAA, a list that includes the name and physical (street) address, or addresses, where the work is carried out for each maintenance provider that performs work for the certificate holder, and a description of the type of maintenance, preventive maintenance, or alteration that is to be performed at each location. The list must be updated with any changes, including additions or deletions, and the updated list provided to the FAA in a format acceptable to the FAA by the last day of each calendar month.