---
title: "21.A.603 Application — Annex I, Initial Airworthiness · Avioverse"
description: "An application for an ETSO authorisation shall be made in a form and manner established by the Agency and shall include an outline of the information…"
url: "https://avioverse.aero/regulations/easa/initial-airworthiness/annex-i/section-a-technical-requirements/21-a-603"
---

# 21.A.603 Application

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

IR Implementing rule

## 21.A.603 Application

(a) An application for an [ETSO](https://avioverse.aero/glossary/easa/etso) authorisation shall be made in a form and manner established by the Agency and shall include an outline of the information required by point 21.A.605.

(b) When a series of minor changes in accordance with point 21.A.611 is anticipated, the applicant shall set forth in its application the basic model number of the [article](https://avioverse.aero/glossary/easa/article) and the associated part numbers with open brackets after it to denote that suffix change letters or numbers (or combinations of them) will be added from time to time.

IR · 21.A.603 — Regulation (EU) No 748/2012 · 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-i/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.