How does the mechanical fuel scheduling system (MEC) determine the fuel demand?

• A. By electronic sensor readings
• B. Through a complex algorithm
• C. Using a mechanical linkage to the collective
• D. By pilot input directly to the engine

Answer: (C)

The mechanical fuel scheduling system (MEC) determines fuel demand using a mechanical linkage to the collective. This system functions by directly connecting the fuel control to the collective pitch control. When the pilot adjusts the collective, it affects the demand for fuel in relation to the power required for the rotor blades. The more the collective is pulled, the more power is required, and in turn, the mechanical system increases the fuel flow to meet that demand.

This linkage allows for a simpler and more direct relationship between pilot input regarding rotor performance and the corresponding fuel needed, ensuring efficient operation of the helicopter's engine while responding to changing flight conditions. The mechanical nature of the system contrasts with electronic or algorithm-based systems, reinforcing its reliability and straightforward operation in the TH-73 helicopter design.