end of the blade contains a readily removable tip cap. Screws fasten the spar and tip pocket rib together. The root pocket of the blade is sealed at its inboard end by an aluminum alloy root cap that is cemented and riveted to the pocket. A stainless steel spar abrasion strip is found at the leading edge of the spar. It starts at blade pocket No. 10 and extends along the entire leading edge, which includes the tip cap. The blade shown in figure 1-17 is fitted with a ice guard. The guard is composed of fine wire braid heating elements. It is interwoven in bands and embedded in a rubber strap, to which is bonded a stainless steel strap. The guard is bonded to the leading edge of the spar, and is molded to the contour of the blade. Rotor Head The rotary-wing head is splined to and supported by the rotary-wing shaft of the main gearbox. The head supports the rotary-wing blades. It is rotated by torque from the main gearbox, and transmits movements of the flight controls to the blades. The principal components of the head are the hub and swashplate. The hub consists of a hub plate and lower plate. It has hinges between each arm of the plates and sleeve-spindles, which are attached to the hinges. There is also a damper-positioner for each wing blade. The swashplate consists of a rotating swashplate and stationary swashplate. Other components of the rotary- wing head are anti flapping restrainers, droop restrainers, adjustable pitch control rods, and rotating and stationary scissors. The swashplate and adjustable pitch control rods permit movement of the flight controls to be transmitted to the rotary-wing blades. The hinges allow limited movement of the blades in relation to the hub. These movements are known as lead, lag, and flap. Lead occurs during slowing of the drive mechanism when the blades have a tendency to remain in motion. Lag is the opposite of lead, and occurs during acceleration when the blade has been at rest and tends to remain at rest. Flap is the tendency of the blade to rise with high-lift demands as it tries to screw itself upward into the air. The damper-positioners restrict lead and lag motion and position the blades for folding. Sleeve-spindles allow each blade to be rotated on its spanwise axis to change the blade pitch. The antiflapping restrainers and droop restrainers restrict flapping motion when the rotary-wing head is slowing or stopped. 1. 2. 3. Pitch link 4. Pitch control beam Rotary rudder blade 5. Rotary rudder hub Spindle 6. Pylon Figure 1-18.—Tail rotor group. TAIL ROTOR GROUP The tail rotor group has helicopter components that provide the aircraft with directional control. See figure 1-18. These components are the pylon, rotary rudder blades, and rotary rudder head. The rotary rudder head includes such items as the hub, spindle, and pitch control beams. Pylon The pylon, shown in figure 1-18, is of aluminum semimonocoque construction. It has beams, bulkheads, stringer, formers, and channels. Various gauges of aluminum skin located on the sides of the box structure are part of the primary pylon structure. Reinforced plastic fairings in the leading and aft surfaces form the airfoil contour of the pylon and are secondary structures. The pylon houses an intermediate gearbox and a tail gearbox. The pylon is attached on the right side of the aircraft to the main fuselage by hinge fittings. These hinge fittings also serve as the pivot point for the pylon to fold alongside the right side of the fuselage. Folding of the pylon reduces the overall length of the H-3 helicopter by 7 1/2 feet, thereby aiding shipboard handling. Rotary Rudder Head The rudder head is  usually located on the left side of the pylon. It produces antitorque forces, which may be varied by the pilot to control flight heading. The 1-18