The reduction gearbox reduces the power turbine output shaft speed from what speed to what speed?

The reduction gearbox serves a crucial role in optimizing the performance of the T-6A's power turbine system by lowering the high rotational speed of the turbine's output shaft to a more manageable and usable speed for applications like propeller drive. The correct answer highlights a transformation from 30,000 revolutions per minute (rpm) to 2,000 rpm, which reflects a significant reduction ratio.

This reduction allows the engine's high-speed power to be effectively transmitted to the propeller, ensuring efficient thrust production while maintaining the overall stability and reliability of the aircraft's operation. The reduced output speed prevents mechanical strain that could occur if trying to utilize the high turbine speeds directly in a drive system.

When evaluating the other options, the speeds listed either do not match the actual operational parameters of the T-6A's reduction gearbox or fall outside the typical range for such systems, making them unsuitable choices for this question. Understanding the correct transformation between the turbine output and propeller input is essential for comprehending the aircraft's performance and configuration.