on these airplanes, any time a swerve develops, centrifugal  force acting on the CG tends to stop the swerving action. If the airplane touches down while drifting or in a crab,  apply aileron toward the high wing and stop the swerve with  the rudder. Brakes are used to correct for turns or swerves  only when the rudder is inadequate. Exercise caution when  applying corrective brake action because it is very easy to  over control and aggravate the situation.  If brakes are used, sufficient brake is applied on the low-wing  wheel (outside of the turn) to stop the swerve. When the wings  are approximately level, the new direction must be maintained  until the airplane has slowed to taxi speed or has stopped. In nose-wheel airplanes, a ground loop is almost always a  result of wheel barrowing. A pilot must be aware that even  though the nose-wheel type airplane is less prone than the  tailwheel-type airplane, virtually every type of airplane,  including large multi-engine airplanes, can be made to ground  loop when sufficiently mishandled. When landing in a crosswind, there may be instances when  a wing rises during the after-landing roll. This may occur  whether or not there is a loss of directional control, depending  on the amount of crosswind and the degree of corrective action. Any time an airplane is rolling on the ground in a crosswind  condition, the upwind wing is receiving a greater force  from the wind than the downwind wing. This causes a lift  differential. Also, as the upwind wing rises, there is an  increase in the AOA, which increases lift on the upwind  wing, rolling the airplane downwind. When the effects of these two factors are great enough, the  upwind wing may rise even though directional control is  maintained. If no correction is applied, it is possible that the  upwind wing rises sufficiently to cause the downwind wing  to strike the ground. In the event a wing starts to rise during the landing roll,  immediately apply more aileron pressure toward the high  wing and continue to maintain direction. The sooner the  aileron control is applied, the more effective it is. The further  a wing is allowed to rise before taking corrective action, the  more airplane surface is exposed to the force of the crosswind.  This diminishes the effectiveness of the aileron. Hydroplaning is a condition that can exist when an airplane  has landed on a runway surface contaminated with standing  water, slush, and/or wet snow. Hydroplaning can have  Reverted Rubber Hydroplaning Hydroplaning Wing Rising After Touchdown Dynamic Hydroplaning serious adverse effects on ground controllability and  braking efficiency. The three basic types of hydroplaning  are dynamic hydroplaning, reverted rubber hydroplaning,  and viscous hydroplaning. Any one of the three can render  an airplane partially or totally uncontrollable anytime during  the landing roll. Dynamic hydroplaning is a relatively high-speed phenomenon  that occurs when there is a film of water on the runway that  is at least one-tenth of an inch deep. As the speed of the  airplane and the depth of the water increase, the water layer  builds up an increasing resistance to displacement, resulting  in the formation of a wedge of water beneath the tire. At  some speed, termed the hydroplaning speed (Vp), the water  pressure equals the weight of the airplane, and the tire is lifted  off the runway surface. In this condition, the tires no longer  contribute to directional control and braking action is nil. Dynamic hydroplaning is related to tire inflation pressure. Data  obtained during hydroplaning tests have shown the minimum  dynamic hydroplaning speed (Vp) of a tire to be 8.6 times  the square root of the tire pressure in pounds per square inch  (PSI). For an airplane with a main tire pressure of 24 pounds,  the calculated hydroplaning speed would be approximately  42 knots. It is important to note that the calculated speed  referred to above is for the start of dynamic hydroplaning.  Once hydroplaning has started, it may persist to a significantly  slower speed depending on the type being experienced. Reverted rubber (steam) hydroplaning occurs during heavy  braking that results in a prolonged locked-wheel skid. Only a  thin film of water on the runway is required to facilitate this  type of hydroplaning. The tire skidding generates enough heat  to cause the rubber in contact with the runway to revert to  its original uncured state. The reverted rubber acts as a seal  between the tire and the runway and delays water exit from  the tire footprint area. The water heats and is converted to  steam, which supports the tire off the runway. Reverted rubber hydroplaning frequently follows an  encounter with dynamic hydroplaning, during which time the  pilot may have the brakes locked in an attempt to slow the  airplane. Eventually the airplane slows enough to where the  tires make contact with the runway surface and the airplane  begins to skid. The remedy for this type of hydroplane is  to release the brakes and allow the wheels to spin up and  apply moderate braking. Reverted rubber hydroplaning is  insidious in that the pilot may not know when it begins, and  it can persist to very slow ground speeds (20 knots or less). 8-35