---
title: "CS-E 780 Icing Conditions — CS-E · Avioverse"
description: "(See AMC E 780) (a)(1) It must be established by tests, unless alternative appropriate evidence is available, that the Engine will function…"
url: "https://avioverse.aero/regulations/easa/cs-e/subpart-e/cs-e-780-icing-conditions"
---

# CS-E 780 Icing Conditions

Engines (CS-E) · CS-E · EAR revision 7 Dec 2023

IR Implementing rule

## CS-E 780 Icing Conditions

(See AMC E 780)

(a)(1) It must be established by tests, unless alternative appropriate evidence is available, that the Engine will function satisfactorily in flight and on the ground when operated throughout the applicable atmospheric icing conditions without unacceptable: (i) immediate or ultimate reduction of Engine performance, (ii) increase of Engine operating temperatures, (iii) deterioration of Engine handling characteristics, and/or (iv) mechanical damage. (2) The applicable atmospheric icing conditions must include the supercooled liquid water conditions defined in CS-Definitions Amendment 2 under ‘Icing Atmospheric Conditions’ for in-flight operation, freezing fog conditions for ground operation, and any additional conditions (such as ice crystal icing conditions, supercooled large drop icing conditions, and snow conditions) applicable to the Engine air intake system in the ice protection specifications (CS 23.1093(b) of CS-23 until Amdt 4 or CS 23.2415 of CS-23 from Amdt 5, CS 25.1093(b), CS 27.1093(b), CS 29.1093(b)) of the Certification Specifications applicable to the aircraft on which the Engine is to be installed, as specified in CS-E 20(b).

(b) In showing compliance with the specifications of CS-E 780(a), all Engine bleeds and mechanical power offtakes permitted during icing conditions must be set at the level assumed to be the most critical, or their effect must be simulated by other acceptable means. It must be established, however, that other likely use of bleed or mechanical power offtake will not lead to Engine malfunctioning.

(c) In showing compliance with the specifications of this paragraph CS-E 780, the conditions associated with a representative installation must be taken into account.

(d) If after the tests it is found that significant damage has occurred, further running or other evidence may be required to show that subsequent Failures are unlikely to occur.

(e) Where an air intake guard is fitted, compliance with the specifications of this paragraph CS-E 780 must be established with the guard in position, unless the guard is required to be retracted during icing conditions, in which case it must be established that its retraction is not affected immediately after a representative delay period.

(f) Ice ingestion

(1) Objective. To demonstrate that the Engine will function satisfactorily following the ingestion of defined quantities of ice, as part of compliance with CS-E 540. Ingestion of ice may result from ice released by the Engine air intake (including after delayed selection of the ice protection system) or from other aircraft surfaces. Compliance with the requirements of this sub-paragraph shall be demonstrated by an Engine ice slab ingestion test or by validated analysis showing equivalence to other means for demonstrating soft body damage tolerance.

(2) Following the ingestion of ice under the conditions of this paragraph, the Engine shall comply with CS-E 780(a).

(3) For an Engine that incorporates or requires the use of a protection device, compliance with this paragraph need not be demonstrated with respect to ice formed forward of the protection device if it is shown that:

(i) such ice is of a size that will not pass through the protection device;

(ii) the protection device will withstand the impact of the ice; and

(iii) the ice stopped by the protection device will not obstruct the flow of air into the Engine resulting in unacceptable effects under CS-E 780(a).

(4) In establishing the ice slab ingestion conditions, the assumed ice quantity and dimensions, the ingestion velocity and the Engine operating conditions must be determined. Those conditions shall be appropriate to the Engine installation on the aircraft. These assumptions must be included in the manuals containing instructions for installing and operating the Engine under CS-E 20(d).

\[Amdt No: E/1]

\[Amdt No: E/4]

IR — CS-E · ED Decision 2015/009/R · CS-E Easy Access Rules · EAR revision 7 Dec 2023

[All rules in SUBPART E – TURBINE ENGINES: TYPE SUBSTANTIATION](https://avioverse.aero/regulations/easa/cs-e/subpart-e)

Consolidated from the EASA Easy Access Rules (revision 7 Dec 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.