---
title: "CS 25.1103 Air intake system ducts and air duct systems — CS-25 · Avioverse"
description: "(See AMC 25.1103) (a) Reserved. Each air intake system must be – (1) Strong enough to prevent structural failure resulting from engine surging;"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-e/cs-25-1103"
---

# CS 25.1103 Air intake system ducts and air duct systems

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

IR Implementing rule

## CS 25.1103 Air intake system ducts and air duct systems

(See AMC 25.1103)

(a) Reserved.

(b) Each air intake system must be –

(1) Strong enough to prevent structural failure resulting from engine surging; and

(2) Fire-resistant if it is in any fire zone for which a fire extinguishing system is required.

(c) Each duct connected to components between which relative motion could exist must have means for flexibility.

(d) For bleed air systems no hazard may result if a duct rupture or failure occurs at any point between the engine port and the aeroplane unit served by the bleed air. (See AMC 25.1103(d).)

\[Amdt 25/18]

IR · CS 25.1103 — CS-25 · ED Decision 2016/010/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

AMC Acceptable means of compliance

## AMC 25.1103(d) Air intake system ducts

For a single failure case leading to a fire and air duct rupture, consideration should be given to the possibility of fire aggravation due to air flowing into a designated fire zone of an engine from the remaining engine(s), or another source outside the affected fire zone.

AMC · AMC 25.1103(d) — CS-25 · ED Decision 2003/2/RM · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART E – POWERPLANT](https://avioverse.aero/regulations/easa/cs-25/subpart-e)

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.