---
title: "21.A.128 Tests: engines, propellers, and control and monitoring units (CMUs) — Annex I, Initial Airworthiness · Avioverse"
description: "Each manufacturer of engines, propellers or CMUs manufactured under this Subpart shall subject each engine, variable pitch propeller, or CMU to an…"
url: "https://avioverse.aero/regulations/easa/initial-airworthiness/annex-i/section-a-technical-requirements/21-a-128"
---

# 21.A.128 Tests: engines, propellers, and control and monitoring units (CMUs)

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

IR Implementing rule

## 21.A.128 Tests: engines, propellers, and control and monitoring units (CMUs)

Each manufacturer of engines, propellers or CMUs manufactured under this Subpart shall subject each engine, variable pitch propeller, or CMU to an acceptable functional test as specified in the type-certificate holder’s documentation, to determine whether it operates properly throughout the range of operation for which it is type certified, as a means of establishing relevant aspects of compliance with point 21.A.125A(a).

IR · 21.A.128 — 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.