Aircraft systems and instrumentsQuestion 670 of 934

The ammeter shows a full-scale minus deflection. What does this indicate?

  1. A malfunction of the alternator or generator
  2. A malfunction of the voltage regulator circuit
  3. A fully charged battery and a normal load
  4. A fault in the magneto ignition system
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Correct answer: A malfunction of the alternator or generator

A full-scale positive deflection indicates a malfunction of the regulator.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Electrical System, page 191

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026