---
title: "CS 25.1731 Powerplant and APU fire detector system; EWIS — CS-25 · Avioverse"
description: "EWIS that are part of each fire or overheat detector system in a fire zone must be at least fire-resistant."
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-h/cs-25-1731"
---

# CS 25.1731 Powerplant and APU fire detector system; EWIS

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

IR Implementing rule

## CS 25.1731 Powerplant and APU fire detector system; EWIS

(a) EWIS that are part of each fire or overheat detector system in a fire zone must be at least fire-resistant.

(b) No EWIS component of any fire or overheat detector system for any fire zone may pass through another fire zone, unless:

(1) It is protected against the possibility of false warnings resulting from fires in zones through which it passes; or

(2) Each zone involved is simultaneously protected by the same detector and extinguishing system.

\[Amdt 25/5]

IR · CS 25.1731 — CS-25 · ED Decision 2008/006/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART H – ELECTRICAL WIRING INTERCONNECTION SYSTEMS](https://avioverse.aero/regulations/easa/cs-25/subpart-h)

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.