Why do some pneumatic deicer boot systems include an electrically operated timer?

The inclusion of an electrically operated timer in pneumatic deicer boot systems is essential for automatically cycling the boots and providing proper rest periods. This cycling helps ensure that the deicer boots inflate and deflate at appropriate intervals, effectively breaking off accumulated ice from the aircraft's surfaces.

When the boots inflate, they expand and flex against the ice, facilitating its separation. However, if the boots remain inflated continuously without a proper rest period, they may not function efficiently, potentially leading to ice re-adhesion or damaging the boots themselves. The timer automates this process, allowing the system to operate optimally without requiring manual intervention from the pilot or crew, thereby enhancing safety and effectiveness during flight in icy conditions.

The other options do not accurately reflect the role of the electrically operated timer. For instance, maintaining constant pressure in the system is more related to the design and operation of the pneumatic system itself, rather than the timer function; controlling the temperature of the boots is unnecessary, as the primary function is to manage inflation cycles; and adjusting airspeed during operation is not relevant to the function of the deicer boots.