---
title: "CS 25.999 Fuel systems drains — CS-25 · Avioverse"
description: "Drainage of the fuel system must be accomplished by the use of fuel strainer and fuel tank sump drains."
url: "https://avioverse.aero/regulations/easa/cs-25/subpart-e/cs-25-999"
---

# CS 25.999 Fuel systems drains

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

IR Implementing rule

## CS 25.999 Fuel systems drains

(a) Drainage of the fuel system must be accomplished by the use of fuel strainer and fuel tank sump drains.

(b) Each drain required by sub-paragraph (a) of this paragraph must –

(1) Discharge clear of all parts of the aeroplane;

(2) Have manual or automatic means for positive locking in the closed position; and

(3) Have a drain valve –

(i) That is readily accessible and which can be easily opened and closed; and

(ii) That is either located or protected to prevent fuel spillage in the event of a landing with landing gear retracted.

IR · CS 25.999 — 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.