What is the consequence of activating the anti-ice system below 10°C TAT?

Activating the anti-ice system below 10°C TAT can lead to potential system damage due to the system being designed to operate under certain temperature conditions. When the outside air temperature is above this threshold, the moisture content can lead to ice forming on the components, potentially causing blockages and other issues within the anti-ice system itself. If the system operates in conditions where ice isn't forming (above 10°C TAT), the components may not adequately dissipate heat, potentially leading to thermal stress or other forms of mechanical failure.

In contrast to this, the other consequences mentioned, such as increased fuel consumption and reduced engine performance, may occur depending on operational circumstances but are not directly tied to the activation below the specified temperature threshold. Meanwhile, asserting that there is no consequence is misleading, as it overlooks the potential risks involved with such operational procedures. The focus on potential system damage highlights the importance of adhering to the operational guidelines for ice protection systems to ensure the aircraft's reliability and safety.