---
title: "26.425 Provision of substantiated sea conditions — ADDITIONAL AIRWORTHINESS SPECIFICATIONS FOR OPERATIONS, Part-26 · Avioverse"
description: "A holder of a type certificate for a small helicopter or a large helicopter shall ensure that the substantiated sea conditions for capsize resistance and…"
url: "https://avioverse.aero/regulations/easa/additional-airworthiness/additional-airworthiness-specifications-for/subpart-c/26-425"
---

# 26.425 Provision of substantiated sea conditions

ADDITIONAL AIRWORTHINESS SPECIFICATIONS FOR OPERATIONS · Regulation (EU) 2015/640 · EAR revision 20 Mar 2026

IR Implementing rule

## 26.425 Provision of substantiated sea conditions

(a) A holder of a type certificate for a [small helicopter](https://avioverse.aero/glossary/easa/small-helicopter) or a [large helicopter](https://avioverse.aero/glossary/easa/large-helicopter) shall ensure that the [substantiated sea conditions](https://avioverse.aero/glossary/easa/substantiated-sea-conditions) for capsize resistance and any associated information relating to the ditching certification or emergency flotation provisions are included in the rotorcraft flight manual (RFM) and provided to all operators.

(b) A holder of a supplemental type certificate for an emergency flotation system that is installed on a small helicopter or a large helicopter shall ensure that the substantiated sea conditions for capsize resistance and any associated information relating to the ditching certification or emergency flotation provisions are included in the RFM and provided to all operators.

IR · 26.425 — Regulation (EU) 2015/640 · Regulation (EU) 2022/1254 · Part-26 Easy Access Rules · EAR revision 20 Mar 2026

[All rules in SUBPART C — HELICOPTERS](https://avioverse.aero/regulations/easa/additional-airworthiness/additional-airworthiness-specifications-for/subpart-c)

Consolidated from the EASA Easy Access Rules (revision 20 Mar 2026, 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.