Which gauge is typically used to measure engine RPM?

• A. Manifold pressure gauge
• B. Vertical speed indicator
• C. Tachometer
• D. Fuel gauge

Answer: (C)

The tachometer is the instrument specifically designed to measure engine RPM (revolutions per minute). It provides vital information about the engine's speed, allowing the pilot to monitor how fast the engine is running, which is crucial for safe operations. Knowing the RPM helps in managing engine performance and ensuring that it operates within the specified limits, preventing potential damage due to over-revving.

In contrast, the manifold pressure gauge measures the pressure of the intake manifold, giving insights into engine load and performance but not directly indicating RPM. The vertical speed indicator, on the other hand, measures the rate of climb or descent of the aircraft and is not involved in assessing engine speed. The fuel gauge simply indicates the level of fuel in the tank and does not relate to engine performance metrics like RPM. Thus, the tachometer is the clear instrument used for measuring engine RPM, as it directly displays the rotational speed of the engine.