Which of the following is a flow-indicating system type used for turbine engines?

• A. Vane-type flow meters
• B. Capacitance-type flow meters
• C. Optical fiber flow meters
• D. Ultrasonic flow meters

Answer: (A)

Flow-indicating systems in turbine engines are designed to show how much fluid is moving through a line in real time. The vane-type flow meter fits this need best because it’s a simple, rugged device: a vane sits in the flow path and rotates proportional to the flow rate. That rotation is connected mechanically to a dial pointer, giving a direct, readable indication of how much fluid is flowing. Its mechanical nature makes it highly robust for the harsh engine environment—vibration, high temperatures, and exposure to fuel—without requiring delicate electronics or optical components. Capacitance-type meters rely on dielectric properties and electronics, which are less rugged for aircraft fuel lines. Optical fiber meters depend on light transmission and can be unreliable in hot, vibrating conditions. Ultrasonic meters need sensors and electronics arranged around the pipe, adding weight and potential failure points. So the vane-type flow meter provides a reliable, straightforward flow indication for turbine engines.