What is the primary purpose of the Mechanical Mixing Unit (MMU)?

• A. It mechanically reduces inherent control coupling by compensating for the effect of different flight control inputs.
• B. It increases hydraulic pressure to the main rotor.
• C. It cools the hydraulic fluid.
• D. It provides electrical power to the flight control system.

Answer: (A)

The main idea here is that the Mechanical Mixing Unit blends the pilot’s control inputs so they don’t fight each other. In a UH-60, moving the cyclic, collective, or pedals can interact due to rotor dynamics and the way hydraulic actuators respond. The MMU mechanically combines these inputs into a single, appropriate set of commands for the flight-control actuators, compensating for how one input would affect the others. This reduces cross-coupling and makes the helicopter respond to the pilot’s intentions more predictably and smoothly. It’s not about hydraulic pressure, cooling, or power supply—the MMU’s purpose is to manage how control inputs are mixed to control the rotor effectively.