Aircraft systems and instrumentsQuestion 609 of 934

What can result from an overly lean mixture during a descent from high altitude?

  1. Spark plug fouling from carbon
  2. Carburetor icing only
  3. Detonation
  4. An increase in oil pressure
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Correct answer: Detonation

An overly lean mixture causes detonation. This may result in rough operation, overheating, and loss of power.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Induction Systems — Mixture Control, page 169

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Questions last reviewed: 18 October 2026