Ice protection systems are designed to keep atmospheric ice from accumulating on aircraft surfaces (particularly leading edges), such as wings, propellers, rotor blades, engine intakes, and environmental control intakes. If ice is allowed to built up to a significant thickness it can change the shape of airfoils and flight control surfaces, degrading the performance, control or handling characteristics of the aircraft. An ice protection system either prevents formation of ice, or enables the aircraft to shed the ice before it can grow to a dangerous thickness.