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Aircraft systems and instrumentsQuestion 657 of 934

When may a pilot use automobile gasoline in an aircraft engine?

  1. When 100LL AVGAS is not available at the airport
  2. When the engine has a low-compression design
  3. Only with an STC for that aircraft
  4. When the temperature is below freezing at night
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Correct answer: Only with an STC for that aircraft

Automobile gas should never be used unless the aircraft has been modified with a Supplemental Type Certificate.

Source: Pilot's Handbook of Aeronautical Knowledge (FAA-H-8083-25C), Chapter 7: Aircraft Systems — Fuel Systems — Fuel Grades, page 187

Practice aircraft systems and instruments

Questions last reviewed: 18 October 2026