What area in the engine does not normally need anti ice protection?

• A. First Stage of the Compressor
• B. Fan
• C. Combustor
• D. Turbine

Answer: (A)

The concept being tested is where icing can occur on an engine and where anti-ice protection is actually applied. Anti-ice is used on surfaces exposed to the external, moisture-laden air where ice can form and block airflow—primarily the engine intake and external leading-edge areas like the nacelle lip and, in some designs, the fan and related front-stage components.

Inside the core, the situation changes. The combustor and turbine operate at very high temperatures, so ice cannot persist there. The first stage of the compressor, though part of the core, is not a surface exposed to ambient freezing conditions in the same way as the external inlet surfaces. It is inside the hot, fast-moving air stream and benefits from the heating effect of compression, which makes icing unlikely and not worth an anti-ice system. For that reason, anti-ice protection is not normally provided for the first stage of the compressor.

In contrast, the fan and nacelle inlet areas are more susceptible to icing because they encounter moist air directly and at colder temperatures, so anti-ice protection is typically required there. The combustor and turbine do not need anti-ice protection due to their high operating temperatures.