Aircraft systems and instrumentsQuestion 618 of 934

What is the critical altitude of a turbocharged engine?

  1. The top altitude for rated horsepower
  2. The altitude where the waste gate first opens fully
  3. The altitude where the oil begins to overheat
  4. The altitude where the propeller reaches maximum rpm
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Correct answer: The top altitude for rated horsepower

Above the critical altitude, power output decreases as in a normally aspirated engine.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Superchargers and Turbosuperchargers — Turbosuperchargers, page 173

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Questions last reviewed: 18 October 2026