Without proper equipment, flying an airplane in icing conditions is a dangerous proposition. But with a deice or anti-ice system installed, this type of operation can be done safely in certain conditions.
Deice boots are a common method with which to shed ice off the aircraft’s forward-facing surfaces. They can be operated either pneumatically with bleed air from a turbine engine or with an engine-driven air pump (vacuum pump) on a piston aircraft.
The deice boots are divided into multiple sections along each forward surface so that airflow isn’t disturbed over the entire span. Within each section, the boot itself features multiple chambers where air is pumped in at different times. As a result, airflow is less affected, and ice is shed more cleanly.
The process begins when a pilot selects the deice system to be active in the cockpit. Then the air from the engine or the pump is fed through a series of tubes and various stages such as an air/oil separator. The boot operation is controlled by a valve that either sucks (for a pump system) or opens (for a pneumatic system) to allow air to fill each chamber. There are also pressure release valves integrated at this point in the system to ensure the proper amount of air pressure enters the boots, and as a way to exhaust the pressure once the boot needs to deflate. Because the boots operate at different times in the cycle, they must be metered. This is done with a series of switch circuits actuated by solenoid step switches.
Related Articles
