---
title: "21.A.305 Approval of parts, appliances, and control and monitoring unit (CMU) components — Annex I, Initial Airworthiness · Avioverse"
description: "In all cases where the approval of a part, appliance or CMU component is explicitly required by Union law () or taking into account the Agency measures…"
url: "https://avioverse.aero/regulations/easa/initial-airworthiness/annex-i/section-a-technical-requirements/21-a-305"
---

# 21.A.305 Approval of parts, appliances, and control and monitoring unit (CMU) components

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

IR Implementing rule

## 21.A.305 Approval of parts, appliances, and control and monitoring unit (CMU) components

In all cases where the approval of a part, appliance or CMU component is explicitly required by Union law () or taking into account the Agency measures referred to in [Article](https://avioverse.aero/glossary/easa/article) 10 of Regulation (EU) No 748/2012, the part, appliance or CMU component shall comply with the applicable [ETSO](https://avioverse.aero/glossary/easa/etso) or with the specifications recognised as equivalent by the Agency in the particular case.

IR · 21.A.305 — Regulation (EU) No 748/2012 · Regulation (EU) 2024/1108 · 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.