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AhaBulb: Stuff Everyone Should Know · ahabulb.com/pilot-alternator-failure-radio-power

Why can an alternator failure eventually silence the aircraft radios?

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  1. Magnetos stop instantly
  2. The vacuum pump powers them
  3. Battery backup is limited

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References

  1. FAA Pilot's Handbook of Aeronautical Knowledge, Chapter 7 www.faa.gov/sites/faa.gov/files/09_phak_ch7.pdf Checked 2026-10-09.

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FlyingIn a typical small airplane, what normally powers the electrical system once the engine is running?FlyingYour only alternator fails in flight. What should you do right away?FlyingWhich transponder code tells ATC your two-way radio has failed?

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