14 CFR §21.147

1. (a)A holder of a production certificate must apply for an amendment to a production certificate in a form and manner prescribed by the FAA.
2. (b)An applicant for an amendment to a production certificate to add a type certificate or model, or both, must comply with §§ 21.135(c), 21.137, 21.138, and 21.150.
3. (c)An applicant may apply to amend its production limitation record to allow the manufacture and installation of an interface component, provided—
   1. (1)The applicant owns or has a license to use the design and installation data for the interface component and makes that data available to the FAA upon request;
   2. (2)The applicant manufactures the interface component;
   3. (3)The applicant's product conforms to its approved type design and the interface component conforms to its approved type design;
   4. (4)The assembled product with the installed interface component is in a condition for safe operation; and
   5. (5)The applicant complies with any other conditions and limitations the FAA considers necessary.