---
title: "CS 25J1189 Shut-off means — CS-25 · Avioverse"
description: "(See AMC 25.1189) (a) Each APU compartment specified in CS 25J1181(a) must have a means to shut-off or otherwise prevent hazardous quantities of…"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-j/cs-25j1189-shut-off-means"
---

# CS 25J1189 Shut-off means

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

IR Implementing rule

## CS 25J1189 Shut-off means

(See AMC 25.1189)

(a) Each APU compartment specified in CS 25J1181(a) must have a means to shut-off or otherwise prevent hazardous quantities of flammable fluids, from flowing into, within, or through any designated fire zone, except that shut-off means are not required for:

(1) Lines, fittings and components forming an integral part of an APU; and

(2) Oil systems for APU installations in which all external components of the oil system, including the oil tanks, are fireproof.

(b) The closing of any fuel shut-off valve for any APU may not make fuel unavailable to the main engines.

(c) Operation of any shut-off may not interfere with the later emergency operation of other equipment.

(d) Each flammable fluid shut-off means and control must be fireproof or must be located and protected so that any fire in a fire zone will not affect its operation.

(e) No hazardous quantity of flammable fluid may drain into any designated fire zone after shut-off.

(f) There must be means to guard against inadvertent operation of the shut-off means and to make it possible for the crew to reopen the shut-off means in flight after it has been closed.

(g) Each tank to APU shut-off valve must be located so that the operation of the valve will not be affected by the APU mount structural failure.

(h) Each shut-off valve must have a means to relieve excessive pressure accumulation unless a means for pressure relief is otherwise provided in the system.

\[Amdt 25/1]

IR — CS-25 · ED Decision 2005/006/R · CS-25 Easy Access Rules · EAR revision 26 Jan 2023

[All rules in SUBPART J – AUXILIARY POWER UNIT INSTALLATIONS](https://avioverse.aero/regulations/easa/cs-25/subpart-j)

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.