---
title: "21L.A.91 Changes to a part of a product covered by a supplemental type certificate — Annex Ib, Initial Airworthiness · Avioverse"
description: "A minor change to a part of a product covered by a supplemental type certificate shall be approved in accordance with Subpart D of this Annex."
url: "https://avioverse.aero/regulations/easa/initial-airworthiness/annex-ib/section-a-technical-requirements/21l-a-91"
---

# 21L.A.91 Changes to a part of a product covered by a supplemental type certificate

Annex Ib · Regulation (EU) No 748/2012 · EAR revision 27 Nov 2025

IR Implementing rule

## 21L.A.91 Changes to a part of a product covered by a supplemental type certificate

(a) A minor change to a part of a product covered by a supplemental type certificate shall be approved in accordance with Subpart D of this Annex.

(b) A major change to that part of a product covered by a supplemental type certificate shall be approved as a separate supplemental type certificate in accordance with this Subpart.

(c) By way of derogation from point (b), a major change to that part of a product covered by a supplemental type certificate submitted by the supplemental type-certificate holder may be approved as a change to the existing supplemental type certificate in accordance with points 21L.A.63 to 21L.A.69.

IR · 21L.A.91 — Regulation (EU) No 748/2012 · Regulation (EU) 2022/1358 · Initial Airworthiness Easy Access Rules · EAR revision 27 Nov 2025

[All rules in SECTION A - TECHNICAL REQUIREMENTS](https://avioverse.aero/regulations/easa/initial-airworthiness/annex-ib/section-a-technical-requirements)

Consolidated from the EASA Easy Access Rules (revision 27 Nov 2025, extracted 13 Oct 2026) for convenience. Not the official publication — verify against the Official Journal of the European Union and the EASA publications before operational use.