---
kind: "section"
citation: "14 C.F.R. § 21.120"
title: "14"
number: "21.120"
heading: "Responsibility of supplemental type certificate holders to provide written permission for alterations."
url: "https://uscodex.org/cfr/14/21.120"
---

# §21.120. Responsibility of supplemental type certificate holders to provide written permission for alterations.


A supplemental type certificate holder who allows a person to use the supplemental type certificate to alter an aircraft, aircraft engine, or propeller must provide that person with written permission acceptable to the FAA.


## Notes

### Amendments

[Doc. No. FAA-2003-14825, 71 FR 52258, Sept. 1, 2006]

### Source

Source: Docket No. 5085, 29 FR 14568, Oct. 24, 1964, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 7572; 49 U.S.C. 106(f), 40105, 40113, 44701-44702, 44704, 44707, 44709, 44711, 44713, 44715, 45303.

### Amendments

[Doc. No. FAA-2003-14825, 71 FR 52258, Sept. 1, 2006]