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Aircraft systems and instrumentsQuestion 591 of 934

An engine has a constant-speed propeller. The pilot wants to decrease power. Which setting is changed first?

  1. The propeller rpm
  2. The mixture
  3. The carburetor heat
  4. Manifold pressure
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Correct answer: Manifold pressure

Reduce manifold pressure before rpm. If rpm is reduced first, manifold pressure increases and may exceed limits.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Propeller — Adjustable-Pitch Propeller, page 167

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026