---
title: "CS 25J1549 APU instruments — CS-25 · Avioverse"
description: "For each APU instrument either a placard or colour markings or an acceptable combination must be provided to convey information on the maximum and (where…"
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-j/cs-25j1549-apu-instruments"
---

# CS 25J1549 APU instruments

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

IR Implementing rule

## CS 25J1549 APU instruments

For each APU instrument either a placard or colour markings or an acceptable combination must be provided to convey information on the maximum and (where applicable) minimum operating limits. Colour coding must comply with the following:

(a) Each maximum and, if applicable, minimum safe operating limit must be marked with a red radial or a red line;

(b) Each normal operating range must be marked with a green arc or green line, not extending beyond the maximum and minimum safe limits;

(c) Each precautionary operating range must be marked with a yellow arc or a yellow line; and

(d) Each APU speed range that is restricted because of excessive vibration stresses must be marked with red arcs or red lines.

\[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.