Which component must be clean on both the inboard and outboard sides to ensure proper de-icing?

The correct choice focuses on the importance of keeping winglets clean on both the inboard and outboard sides for effective de-icing. Winglets, which are the vertical extensions at the tips of wings, play a crucial role in improving aerodynamic efficiency by reducing drag and enhancing lift. If they are contaminated with ice, snow, or frost, it can disrupt airflow, leading to adverse aerodynamic performance and potential safety risks during flight.

Clean surfaces allow for the proper application and effectiveness of de-icing measures. Ice accumulation on winglets can significantly affect the overall performance of the aircraft by leading to loss of control and reduced fuel efficiency. Therefore, ensuring that winglets are free from ice is essential in maintaining safe flight operations.

Other components, while important, may not have the same level of impact on overall aerodynamics as winglets. For instance, while wing flaps and control surfaces are also critical to aircraft performance, their specific de-icing requirements might differ, and their cleaning may not be as crucial as that of the winglets in this context.