CS 25.1193 Cowling and nacelle skin

• ED Decision 2018/005/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.1193 Cowling and nacelle skin ED Decision 2018/005/R (a) Each cowling must be constructed and supported so that it can resist any vibration, inertia, and air load to which it may be subjected in operation. (b) Cowling must meet the drainage and ventilation requirements of [CS 25.1187](#_DxCrossRefBm1709821542). (c) On aeroplanes with a diaphragm isolating the engine power section from the engine accessory section, each part of the accessory section cowling subject to flame in case of fire in the engine power section of the powerplant must – (1) Be fireproof; and (2) Meet the requirements of [CS 25.1191](#_DxCrossRefBm1709821358). (d) Each part of the cowling subject to high temperatures due to its nearness to exhaust system parts or exhaust gas impingement must be fireproof. (e) Each aeroplane must: (1) Be designed and constructed so that no fire originating in any fire zone can enter, either through openings or by burning through external skin, any other zone or region where it would create additional hazards; (2) Meet sub-paragraph (e)(1) of this paragraph with the landing gear retracted (if applicable); and (3) have cowlings and nacelles skins, in areas subject to flame if a fire starts in an engine fire zone, complying with the following: (i) For in-flight operations, cowlings and nacelles skins must be fireproof in the complete concerned areas, and (ii) For ground operations, cowlings and nacelles skins must be: (a) Fireproof in the portions of the concerned areas where a skin burn through would affect critical areas of the aeroplane, and (b) Fire-resistant or compliant with subparagraph (e)(1) of this paragraph in the remaining portions of the concerned areas. (4) Be designed and constructed to minimise the likelihood of any in-flight opening or loss of a cowling that could prevent continued safe flight and landing. (f) The retention system of each removable or openable cowling must: (1) keep the cowling closed and secured under the operational loads identified in subparagraph (a) of this paragraph following either of the following conditions: (i) improper fastening of any single latching, locking, or other retention device, or (ii) the failure of any single latch or hinge. (2) have readily accessible means to close and secure the cowling that do not require excessive force or manual dexterity; and (3) have a reliable means for effectively verifying that the cowling is secured prior to each take-off. (See [AMC 25.1193(e)](#_DxCrossRefBm1709821552)) [Amdt 25/13] [Amdt 25/18] [Amdt 25/21]