How is the MFC adjusted in the system?

The correct answer regarding the adjustment of the MFC (Main Fuel Control) pertains to the specific rate at which the speed changes with each click adjustment. In this system, every click changes the speed by 12 rpm. This increment is based on the designed sensitivity and calibration of the MFC when tuning gas turbine engine parameters.

Understanding this specific adjustment is crucial because it affects the overall performance and responsiveness of the gas turbine. Changes in fuel flow directly influence the engine speed, and knowing the precise adjustment per click helps technicians make more accurate and necessary modifications during operation.

While the other options present different speeds per click, they do not align with the established specification for this system. Each of those figures (10 rpm, 15 rpm, 20 rpm) could be representative of other systems or components but not the MFC in this context. Knowing the correct adjustment rate allows for effective troubleshooting and maintenance when ensuring optimal engine performance.