Dynamic rollover is possible even during normal takeoffs and  landings on relatively level ground, if one wheel or skid is on  the ground and thrust (lift) is approximately equal to the weight  of the helicopter. If the takeoff or landing is not performed  properly, a roll rate could develop around the wheel or skid  that is on the ground. When taking off or landing, perform the  maneuver smoothly and carefully adjust the cyclic so that no  pitch or roll movement rates build up, especially the roll rate.  If the bank angle starts to increase to an angle of approximately  5–8°, and full corrective cyclic does not reduce the angle, the  collective should be reduced to diminish the unstable rolling  condition. Excessive bank angles can also be caused by landing  gear caught in a tie down strap, or a tie down strap still attached  to one side of the helicopter. Lateral loading imbalance (usually  outside published limits) is another contributing factor. During slope operations, excessive application of cyclic  control into the slope, together with excessive collective pitch  control, can result in the downslope skid or landing wheel  rising sufficiently to exceed lateral cyclic control limits, and  an upslope rolling motion can occur.  [Figure 11-6] Under normal conditions on a slope, the collective should  not be pulled suddenly to get airborne because a large and  abrupt rolling moment in the opposite direction could occur.  Excessive application of collective can result in the upslope  skid or wheel rising sufficiently to exceed lateral cyclic  control limits. This movement may be uncontrollable. If the  helicopter develops a roll rate with one skid or wheel on the  ground, the helicopter can roll over on its side. thrust (lift). A smooth, moderate collective reduction, at a  rate of less than approximately full up to full down in two  seconds, may be adequate to stop the rolling motion. Take  care, therefore, not to dump collective at an excessively high  rate, as this may cause a main rotor blade to strike the fuselage.  Additionally, if the helicopter is on a slope and the roll starts  toward the upslope side, reducing collective too fast may create  a high roll rate in the opposite direction. When the upslope skid  or wheel hits the ground, the dynamics of the motion can cause  the helicopter to bounce off the upslope skid or wheel, and the  inertia can cause the helicopter to roll about the downslope  ground contact point and over on its side.  [Figure 11-7]  When performing slope takeoff and landing maneuvers, follow  the published procedures and keep the roll rates small. Slowly  raise the downslope skid or wheel to bring the helicopter level,  and then lift off. During landing, first touch down on the  upslope skid or wheel, then slowly lower the downslope skid  or wheel using combined movements of cyclic and collective.  If the helicopter rolls approximately 5–8° to the upslope side,  decrease collective to correct the bank angle and return to level  attitude, then start the landing procedure again. The collective is more effective in controlling the rolling  motion than lateral cyclic, because it reduces the main rotor  To help avoid dynamic rollover: Figure 11-7.  Downslope rolling motion.  Figure 11-6.  Upslope rolling motion. 2.  Use extreme caution when hovering close to fences,  sprinklers, bushes, runway/taxi lights, tiedown cables,  deck nets, or other obstacles that could catch a skid or  wheel. Aircraft parked on hot asphalt overnight might  find the landing gear sunk in and stuck as the ramp  cooled during the evening. 1.  Always practice hovering autorotations into the wind,  and be wary when the wind is gusty or greater than 10  knots. Precautions Use of Collective Slope Takeoffs and Landings Normal Takeoffs and Landings Tail rotor thrust Area of critical rollover Horizontal Slope Full opposite cyclic limit  to prevent rolling motion Tail rotor thrust Area of critical rollover Horizontal Slope Full opposite cyclic limit  to prevent rolling motion 11-13