Which option is NOT one of the three basic types of turbine fuel control units?

• A. Hydraulic throttle control
• B. FADEC
• C. Hydromechanical electronic
• D. Hydromechanical

Answer: (A)

Turbine fuel control units are categorized by how the fuel metering is controlled: a purely hydraulic/hydromechanical approach, a hybrid that combines hydromechanical elements with electronic sensing, and a full digital engine control. The three main types are hydromechanical, hydromechanical electronic, and FADEC (Full Authority Digital Engine Control). Hydraulic throttle control describes a mode or mechanism for opening and closing fuel flow, but it is not a recognized classification of the control architecture itself. Therefore, it isn’t considered one of the three basic types.