---
title: "Appendix 4 Examples of changes that may require full-scale fatigue testing — CS-25 · Avioverse"
description: "The following are examples of types of modifications that may require full-scale fatigue testing:"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-c/appendix-4"
---

# Appendix 4 Examples of changes that may require full-scale fatigue testing

Large Aeroplanes (CS-25) · CS-25 · EAR revision 26 Jan 2023

Appendix Appendix

## Appendix 4 Examples of changes that may require full-scale fatigue testing

The following are examples of types of modifications that may require full-scale fatigue testing:

(1) passenger-to-freighter conversions (including addition of cargo doors);

(2) gross weight increases (e.g. increased operating weights, increased zero-fuel weights, increased landing weights, and increased maximum take-off weights);

(3) installation of fuselage cut-outs (e.g. passenger entry doors, emergency exit doors or crew escape hatches, fuselage access doors, and cabin window relocations);

(4) complete re-engine or pylon change;

(5) engine hush kits;

(6) wing modifications (e.g. installation of winglets, changes in flight-control settings such as flap droop, and change of wing trailing-edge structure);

(7) modified or replaced skin splice;

(8) any modification that affects three or more stiffening members (e.g. wing stringers and fuselage frames);

(9) a modification that results in operational-mission change, which significantly changes the original equipment manufacturer’s load/stress spectrum (e.g. extending the flight duration from 2 hours to 10 hours); and

(10) a modification that changes areas of the fuselage from being externally inspectable using visual means to being non-inspectable (e.g. installation of a large, external fuselage doubler that results in hiding details beneath it).

\[Amdt 25/19]

APPENDIX · Appendix 4 — CS-25 · ED Decision 2017/015/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART C – STRUCTURE](https://avioverse.aero/regulations/easa/cs-25/subpart-c)

Consolidated from the EASA Easy Access Rules (revision 26 Jan 2023, 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.