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During the run-up magneto check, what indication is normal when switching from BOTH to a single magneto?

Choices

  • ✓ A small drop in RPMcorrect

    A slight RPM drop is normal because one spark plug per cylinder is now firing.

  • A large increase in RPM

    RPM should not rise when switching to a single magneto.

  • No change and then engine shutdown

    No drop at all can indicate a grounding problem, not normal operation.

  • A complete loss of oil pressure

    The magneto check does not affect oil pressure.

Why

On a single magneto only one spark plug per cylinder fires, so a small RPM drop is normal; an excessive drop or no drop at all indicates a problem.

FAA source: PHAK Ch. 7browse the reference library →

This is taught in Ignition, Induction and Carburetor Ice — study the lessons free, then practice with grading and mastery tracking.

Original study question written for this course — representative of FAA knowledge-test topics, not an actual current FAA exam question.

During the run-up magneto check, what indication is normal when switc… · PPL Free Ground School