What does the spinner enclose in the tail rotor assembly?

The spinner in the tail rotor assembly is designed to enclose critical components, specifically the dome, barrel, and control assemblies. The dome serves as a protective cover for the control mechanisms, while the barrel contains elements necessary for the functioning of the tail rotor. These components work together to ensure proper pitch control and overall stability of the tail rotor, which is essential for directional control of the helicopter.

The other choices do not accurately represent what is enclosed by the spinner. Enclosures like gearboxes and hydraulic systems, or components relating to the main rotor system, do not fall under the tail rotor assembly’s spinner, focusing instead on other areas of the helicopter's structure and functionality. Understanding the specific roles of the dome, barrel, and control assemblies emphasizes the importance of the spinner in maintaining the integrity and performance of the tail rotor system.