CS 25.1093 Air intake system de-icing and anti-icing provisions

• ED Decision 2016/010/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.1093 Air intake system de-icing and anti-icing provisions ED Decision 2016/010/R (See AMC 25.1093) (a) Reserved. (b) Turbine engines Each engine, with all icing protection systems operating, must: (1) Operate throughout its flight power range, including the minimum descent idling speeds, in the icing conditions defined in Appendices [C](#_DxCrossRefBm1709820681), [O](#_DxCrossRefBm1709820665) and [P](#_DxCrossRefBm1709821510), and in falling and blowing snow within the limitations established for the aeroplane for such operation, without the accumulation of ice on the engine, air intake system components or airframe components that would do any of the following: (i) Adversely affect installed engine operation or cause a sustained loss of power or thrust; or an unacceptable increase in gas path operating temperature; or an airframe/engine incompatibility; or (ii) Result in unacceptable temporary power or thrust loss or engine damage; or (iii) Cause a stall, surge, or flameout or loss of engine controllability (for example, rollback). (2) Idle for a minimum of 30 minutes on the ground in the following icing conditions shown in Table 1 below, unless replaced by similar test conditions that are more critical. These conditions must be demonstrated with the available air bleed for icing protection at its critical condition, without adverse effect, followed by an acceleration to take-off power or thrust, in accordance with the procedures defined in the aeroplane flight manual. During the idle operation the engine may be run up periodically to a moderate power or thrust setting in a manner acceptable to the Agency. The applicant must document the engine run-up procedure (including the maximum time interval between run-ups from idle, run-up power setting, and duration at power), the associated minimum ambient temperature, if any, and the maximum time interval. These conditions must be used in the analysis that establishes the aeroplane operating limitations in accordance with [CS 25.1521](#_DxCrossRefBm1709820849). (See AMC 25.1093(b)) Table 1- Icing conditions for ground tests <table border="1" cellpadding="0" cellspacing="0" width="606"><tr><td valign="top" width="103"><p><b>Condition</b></p></td><td valign="top" width="105"><p><b>Total air temperature</b></p></td><td valign="top" width="131"><p><b>Water concentration (minimum)</b></p></td><td valign="top" width="116"><p><b>Mean effective particle diameter</b></p></td><td valign="top" width="151"><p><b>Demonstration</b></p></td></tr><tr><td valign="top" width="103"><p>(i) Rime ice condition</p></td><td valign="top" width="105"><p>-18 to -9°C </p><p>(0 to 15°F)</p></td><td valign="top" width="131"><p>Liquid—0.3 g/m3</p></td><td valign="top" width="116"><p>15–25 µm</p></td><td valign="top" width="151"><p>By test, analysis or combination of the two.</p></td></tr><tr><td valign="top" width="103"><p>(ii) Glaze ice condition</p></td><td valign="top" width="105"><p>-9 to -1°C </p><p>(15 to 30°F)</p></td><td valign="top" width="131"><p>Liquid—0.3 g/m3</p></td><td valign="top" width="116"><p>15–25 µm</p></td><td valign="top" width="151"><p>By test, analysis or combination of the two.</p></td></tr><tr><td valign="top" width="103"><p>(iii) Large drop condition</p></td><td valign="top" width="105"><p>-9 to -1°C </p><p>(15 to 30°F)</p></td><td valign="top" width="131"><p>Liquid—0.3 g/m3</p></td><td valign="top" width="116"><p>100-3000 µm</p></td><td valign="top" width="151"><p>By test, analysis or combination of the two.</p></td></tr></table> [Amdt 25/16] [Amdt 25/18]