TH-73 Trainer Helicopter Systems Practice Test 2025 – The Complete Guide to Master Your Certification!

The correct choice is the LVDT, or Linear Variable Differential Transformer, which plays a critical role in providing feedback to the fuel control unit (FCU).

In helicopter dynamics, precise control of fuel flow to the engines is essential for optimal performance and safety. The LVDT is a sensor that measures linear displacement. In the context of the helicopter's fuel system, it typically assesses the position of various components related to the fuel delivery system, such as throttle or collective pitch inputs.

By sending a signal to the FCU, the LVDT informs the unit of the current position of the throttle lever or other related mechanisms. This data helps the FCU adjust the fuel flow accordingly, ensuring the engine receives the correct amount of fuel based on the pilot's input and current flight conditions. Such precise regulation supports efficient engine performance and enhances the overall control of the helicopter.

In contrast, the swash plate, collective pitch gauge, and mixing unit have different functions that do not directly provide signals to the FCU. The swash plate is involved in controlling rotor blade pitch, the collective pitch gauge displays the pitch setting but does not provide a signal, and the mixing unit is responsible for adjusting inputs before they affect the rotor system.