---
title: "ETSO-C27a — CS-ETSO · Avioverse"
description: "Twin Seaplane Floats 1 Applicability This ETSO provides the requirements which twin seaplanes floats that are designed and manufactured on or after the…"
url: "https://avioverse.aero/regulations/easa/cs-etso/subpart-b/etso-c27a"
---

# ETSO-C27a

European Technical Standard Orders (CS-ETSO) · CS-ETSO · EAR revision 1 Oct 2026

IR Implementing rule

## ETSO-C27a

Twin Seaplane Floats

1 Applicability

This ETSO provides the requirements which twin seaplanes floats that are designed and manufactured on or after the date of this ETSO must meet in order to be identified with the applicable ETSO marking.

2 Procedures

2.1 General

The applicable procedures are detailed in CS-ETSO, Subpart A.

2.2 Specific

None.

3 Technical conditions

3.1 Basic

3.1.1 Minimum Performance Standard

The applicable standards are those provided in Aerospace Industries of America, Inc., National Aerospace Standard (NAS) 807, Revision 2, Twin Seaplane Floats, dated 30 June 2017.

3.1.2 Environmental Standard

See CS-ETSO, Subpart A, paragraph 2.1.

3.1.3 Software

See CS-ETSO, Subpart A, paragraph 2.2.

3.1.4 Airborne Electronic Hardware

See CS-ETSO, Subpart A, paragraph 2.3.

3.2 Specific

3.2.1 Functionality

The standards of this ETSO apply to twin seaplane floats that are suitable for use on aeroplanes.

3.2.2 Failure Condition Classification

A failure condition classification is not required.

3.2.3 Functional Qualification

The materials and workmanship must conform to the requirements specified in Section 3 of NAS 807, Revision 2. The functional performance must be demonstrated under the test conditions specified in Section 4 of NAS 807, Revision 2. The applicant must define the design parameters to which the article is qualified (e.g. maximum aeroplane weight, Vso, etc.).

4 Marking

4.1 General

See CS-ETSO, Subpart A, paragraph 1.2.

4.2 Specific

None.

5 Availability of Referenced Documents

See CS-ETSO, Subpart A, paragraph 3.

\[Amdt ETSO/16]

IR · ETSO-C27a — CS-ETSO · ED Decision 2020/011/R · CS-ETSO Easy Access Rules · EAR revision 1 Oct 2026

[All rules in SUBPART B – LIST OF ETSOs](https://avioverse.aero/regulations/easa/cs-etso/subpart-b)

Consolidated from the EASA Easy Access Rules (revision 1 Oct 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.