the antifreeze solution chemically breaks down the bond  between the ice and airframe. This allows aerodynamic  forces to carry the ice away. Thus, the system clears the  airframe of accumulated ice before transitioning to anti-ice  protection.  Figure 15-16  shows a chemical anti-ice system. The TKS™ weeping wing system contains formed titanium  panels that are laser drilled with over 800 tiny holes  (.0025-inch diameter) per square inch. These are mated  with non-perforated stainless-steel rear panels and bonded  to wing and stabilizer leading edges. As fluid is delivered  from a central reservoir and pump, it seeps through the holes.  Aerodynamic forces cause the fluid to coat the upper and  lower surfaces of the airfoil. The glycol-based fluid prevents  ice from adhering to the aircraft structure. Some aircraft with weeping wing systems are certified to  fly into known icing conditions. Others use it as a hedge  against unexpected ice encountered in flight. The systems  are basically the same. Reservoir capacity permits 1- 2 hours  of operation. TKS$^{TM}$ weeping wings are used primarily on  reciprocating aircraft that lack a supply of warm bleed air  for the installation of a thermal anti-ice system. However,  the system is simple and effective leading to its use on some  turbine powered corporate aircraft as well. GA aircraft and turboprop commuter-type aircraft often use a  pneumatic deicing system to break off ice after it has formed  on the leading-edge surfaces. The leading edges of the wings  and stabilizers have inflatable boots attached to them. The  boots expand when inflated by pneumatic pressure, which  breaks away ice accumulated on the boot. Most boots are  inflated for 6 to 8 seconds. They are deflated by vacuum  suction. The vacuum is continuously applied to hold the boots  tightly against the aircraft while not in use.  Figure 15-16.  Chemical deicing system.  15-12 Slinger ring in spinner Proportioning unit Proportioning unit High pressure switch Vent Low pressure switch Porous panel on vertical stabilizer Windshield pump Proportioning unit Porous panel on stabilizer Porous panel on wing Filter Solenoid valve Metering pump Spray bar Tank 3/16" OD nylon 5/16" OD nylon 1/2" OD nylon 3/16" OD stainless steel Wing and Stabilizer Deicing Systems