---
title: "Fatigue-critical modified structure — EASA Definition · Avioverse"
description: "Article 2, Regulation (EU) 2015/640: “fatigue-critical modified structure” (FCMS) means any fatigue critical structure of an aeroplane introduced or…"
url: "https://avioverse.aero/glossary/easa/fatigue-critical-modified-structure"
---

# fatigue-critical modified structure

EASA defines “fatigue-critical modified structure” in one regulation. The wording below is reproduced verbatim from the EASA Easy Access Rules, with a link to the paragraph it comes from.

> “fatigue-critical modified structure” (FCMS) means any fatigue critical structure of an aeroplane introduced or affected by a change to its type design and that is not already listed as part of the fatigue-critical baseline structure;

Article 2 · Additional Airworthiness Specifications · Regulation (EU) 2015/640 · Easy Access Rules, 20 Mar 2026 revision · [Read Article 2](https://avioverse.aero/regulations/easa/additional-airworthiness/cover-regulation/general#article-2)

## Defined in the same article

- [airworthiness limitation section](https://avioverse.aero/glossary/easa/airworthiness-limitation-section)
- [baseline structure](https://avioverse.aero/glossary/easa/baseline-structure)
- [corrosion prevention and control programme](https://avioverse.aero/glossary/easa/corrosion-prevention-and-control-programme)
- [damage tolerance evaluation](https://avioverse.aero/glossary/easa/damage-tolerance-evaluation)
- [damage tolerance inspection](https://avioverse.aero/glossary/easa/damage-tolerance-inspection)
- [fatigue-critical baseline structure](https://avioverse.aero/glossary/easa/fatigue-critical-baseline-structure)
- [fatigue-critical structure](https://avioverse.aero/glossary/easa/fatigue-critical-structure)
- [large aeroplane](https://avioverse.aero/glossary/easa/large-aeroplane)