CS 27.1505 Never-exceed speed

• ED Decision 2023/001/R found in: CS-27 Amdt 10 - Small Rotorcraft (Feb 2023)
• ED Decision 2003/15/RM found in: CS-27 Amdt 9 - Small Rotorcraft (Dec 2021)

CS 27.1505 Never-exceed speed ED Decision 2023/001/R (a) The never-exceed speed, VNE, must be established so that it is: (1) Not less than 74 km/h (40 knots) (CAS); and (2) Not more than the lesser of: (i) 0.9 times the maximum forward speeds established under [CS 27.309](#_DxCrossRefBm8893831); (ii) 0.9 times the maximum speed shown under [CS 27.251](#_DxCrossRefBm8893819) and [27.629](#_DxCrossRefBm8893907); or (iii) 0.9 times the maximum speed substantiated for advancing blade tip mach number effects. (b) VNE may vary with altitude, rpm, temperature, and weight, if: (1) No more than two of these variables (or no more than two instruments integrating more than one of these variables) are used at one time; and (2) The ranges of these variables (or of the indications on instruments integrating more than one of these variables) are large enough to allow an operationally practical and safe variation of VNE. (c) For helicopters, a stabilised power-off VNE denoted as VNE (power-off) may be established at a speed less than VNE established pursuant to sub-paragraph (a), if the following conditions are met: (1) VNE (power-off) is not less than a speed midway between the power-on VNE and the speed used in meeting the requirements of: (i) [CS 27.65(b)](#_DxCrossRefBm8893796) for single-engine helicopters; and (ii) [CS 27.67](#_DxCrossRefBm8893797) for multi-engine helicopters. (2) Unless it is automatically displayed to the crew, the VNE (power-off) is – (i) A constant airspeed; or (ii) A constant amount less than power-on VNE; or (iii) A constant airspeed for a portion of the altitude range for which certification is requested, and a constant amount less than power-on VNE for the remainder of the altitude range. CS 27.1505 Never-exceed speed ED Decision 2003/15/RM (a) The never-exceed speed, VNE, must be established so that it is: (1) Not less than 74 km/h (40 knots) (CAS); and (2) Not more than the lesser of: (i) 0.9 times the maximum forward speeds established under [CS 27.309](#_DxCrossRefBm472493266); (ii) 0.9 times the maximum speed shown under [CS 27.251](#_DxCrossRefBm472493261) and [27.629](#_DxCrossRefBm472493334); or (iii) 0.9 times the maximum speed substantiated for advancing blade tip mach number effects. (b) VNE may vary with altitude, rpm, temperature, and weight, if: (1) No more than two of these variables (or no more than two instruments integrating more than one of these variables) are used at one time; and (2) The ranges of these variables (or of the indications on instruments integrating more than one of these variables) are large enough to allow an operationally practical and safe variation of VNE. (c) For helicopters, a stabilised power-off VNE denoted as VNE (power-off) may be established at a speed less than VNE established pursuant to sub-paragraph (a), if the following conditions are met: (1) VNE (power-off) is not less than a speed midway between the power-on VNE and the speed used in meeting the requirements of: (i) [CS 27.65(b)](#_DxCrossRefBm472493238) for single engine helicopters; and (ii) [CS 27.67](#_DxCrossRefBm472493239) for multi-engine helicopters. (2) VNE (power-off) is – (i) A constant airspeed; (ii) A constant amount less than power-on VNE; or (iii) A constant airspeed for a portion of the altitude range for which certification is requested, and a constant amount less than power-on VNE for the remainder of the altitude range.