FAA Powerplant Written Practice Test

What device manages turbocharger speed and output without pilot input up to critical altitude?

1. Wastegate controller

2. Absolute pressure controller

3. Turbocharger bypass valve

4. Manual throttle control

The correct answer is: Absolute pressure controller

The device that manages turbocharger speed and output automatically, without requiring pilot input up to critical altitude, is known as the absolute pressure controller. This component monitors the manifold pressure and adjusts the wastegate position, allowing turbocharger operation to optimize engine performance. At lower altitudes, the absolute pressure controller ensures that the turbocharger provides the necessary boost to the engine. As the aircraft ascends, the absolute pressure controller compensates for decreasing atmospheric pressure, maintaining optimal performance until it reaches the critical altitude. This system enables the engine to utilize the turbocharger efficiently, adjusting its operation based solely on environmental conditions rather than manual adjustments by the pilot. The other options, such as the wastegate controller and the turbocharger bypass valve, are also involved in managing turbocharger functionality. However, they often require pilot input or do not directly manage output in the same way that an absolute pressure controller does in compliance with altitude changes. Manual throttle control, as the name suggests, depends entirely on pilot input and does not automatically adjust based on turbocharger requirements or altitude.