CS-VLA 425 Gust loads

• ED Decision 2003/18/RM found in: CS-VLA Amdt 1 - Very Light Aeroplanes (Mar 2009)

CS-VLA 425 Gust loads ED Decision 2003/18/RM (a) Each horizontal tail surface must be designed for loads resulting from - (1) Gust velocities specified in [CS-VLA 333(c)](#_DxCrossRefBm584936674) with flaps retracted; and (2) Positive and negative gusts of 7.62 m/s nominal intensity at VF corresponding to the flight conditions specified in [CS-VLA 345(a)(2)](#_DxCrossRefBm584936673). (b) The average loadings in figure B3 and the distribution of figure B8 may be used to determine the incremental gust loads for the requirements of subparagraph (a) applied as both up and down increments for subparagraph (c). (c) When determining the total load on the horizontal tail for the conditions specified in sub-paragraph (a) of this paragraph, the initial balancing tail loads for steady unaccelerated flight at the pertinent design speeds VF, VC and VD must first be determined. The incremental tail load resulting from the gusts must be added to the initial balancing tail load to obtain the total tail load. (d) In the absence of a more rational analysis, the incremental tail load due to the gust, must be computed as follows:  <table border="0" cellpadding="0" cellspacing="0" width="567"><tr><td colspan="3" valign="top" width="567"><p>where - </p></td></tr><tr><td valign="top" width="70"><p>∆L_ht</p></td><td valign="top" width="16"><p>= </p></td><td valign="top" width="481"><p>incremental horizontal tail load (daN); </p></td></tr><tr><td valign="top" width="70"><p>K_g</p></td><td valign="top" width="16"><p>= </p></td><td valign="top" width="481"><p>gust alleviation factor defined in <a href="#_DxCrossRefBm584936679">CS-VLA 341</a>; </p></td></tr><tr><td valign="top" width="70"><p>U_de</p></td><td valign="top" width="16"><p>= </p></td><td valign="top" width="481"><p>derived gust velocity (m/s); </p></td></tr><tr><td valign="top" width="70"><p>V</p></td><td valign="top" width="16"><p>= </p></td><td valign="top" width="481"><p>aeroplane equivalent speed (m/s);</p></td></tr><tr><td valign="top" width="70"><p>a_ht</p></td><td valign="top" width="16"><p>= </p></td><td valign="top" width="481"><p>slope of horizontal tail lift curve per radian;</p></td></tr><tr><td valign="top" width="70"><p>S_ht</p></td><td valign="top" width="16"><p>= </p></td><td valign="top" width="481"><p>area of horizontal tail (m²); and </p></td></tr><tr><td valign="top" width="70"><p><div class="image-container"><img alt="EASA EAR image" src="/static/files/file_CbObCD5goL3/image037.jpg"/></div></p></td><td valign="top" width="16"><p>=</p></td><td valign="top" width="481"><p>downwash factor</p></td></tr></table>