CS 25.509 Towing Loads

• ED Decision 2013/010/R found in: CS-25 Amdt 27 - Large Aeroplanes (Jan 2023)

CS 25.509 Towing Loads ED Decision 2013/010/R (See [AMC 25.509](#_DxCrossRefBm1709821027)) (a) The towing loads specified in sub-paragraph (d) of this paragraph must be considered separately. These loads must be applied at the towing fittings and must act parallel to the ground. In addition – (1) A vertical load factor equal to 1·0 must be considered acting at the centre of gravity; (2) The shock struts and tyres must be in their static positions; and (3) With WT as the design ramp weight, the towing load, FTOW is – (i) 0.3 WT for WT less than 30 000 pounds; (ii)  for WT between 30 000 and 100 000 pounds; and (iii) 0·15 WT for WT over 100 000 pounds. (b) For towing points not on the landing gear but near the plane of symmetry of the aeroplane, the drag and side tow load components specified for the auxiliary gear apply. For towing points located outboard of the main gear, the drag and side tow load components specified for the main gear apply. Where the specified angle of swivel cannot be reached, the maximum obtainable angle must be used. (c) The towing loads specified in sub-paragraph (d) of this paragraph must be reacted as follows: (1) The side component of the towing load at the main gear must be reacted by a side force at the static ground line of the wheel to which the load is applied. (2) The towing loads at the auxiliary gear and the drag components of the towing loads at the main gear must be reacted as follows: (i) A reaction with a maximum value equal to the vertical reaction must be applied at the axle of the wheel to which the load is applied. Enough aeroplane inertia to achieve equilibrium must be applied. (ii) The loads must be reacted by aeroplane inertia. (d) The prescribed towing loads are as specified in the following Table: <table border="1" cellpadding="0" cellspacing="0" width="568"><thead><tr><td rowspan="2" width="90"><p><b>Tow Point </b></p></td><td rowspan="2" width="139"><p><b>Position </b></p></td><td colspan="3" width="340"><p><b>Load</b></p></td></tr><tr><td width="111"><p><b>Magnitude </b></p></td><td width="38"><p><b>No. </b></p></td><td width="191"><p><b>Direction </b></p></td></tr></thead><tr><td width="90"><p>Main gear </p></td><td width="139"></td><td width="111"><p>0·75 F_TOWper main gear unit </p></td><td width="38"><p>1 </p><p>2 </p><p>3 </p><p>4 </p></td><td width="191"><p>Forward, parallel to drag axis </p><p>Forward, at 30° to drag axis </p><p>Aft, parallel to drag axis </p><p>Aft, at 30° to drag axis </p></td></tr><tr><td rowspan="4" width="90"><p>Auxiliary gear </p></td><td width="139"><p>Swivelled forward </p></td><td rowspan="2" width="111"><p>1·0 F_TOW</p></td><td width="38"><p>5</p><p>6</p></td><td width="191"><p>Forward</p><p>Aft</p></td></tr><tr><td width="139"><p>Swivelled aft </p></td><td width="38"><p>7</p><p>8</p></td><td width="191"><p>Forward</p><p>Aft</p></td></tr><tr><td width="139"><p>Swivelled 45° from forward </p></td><td rowspan="2" width="111"><p>0·5 F_TOW</p></td><td width="38"><p>9</p><p>10</p></td><td width="191"><p>Forward, in plane of wheel</p><p>Aft, in plane of wheel</p></td></tr><tr><td width="139"><p>Swivelled 45°from aft</p></td><td width="38"><p>11</p><p>12</p></td><td width="191"><p>Forward, in plane of wheel</p><p>Aft, in plane of wheel</p></td></tr></table> [Amdt 25/13]