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FAA to STC Holders: No Ethanol in Auto Fuel

EAA's Alcohol Test Kit

The FAA has issued a special airworthiness information bulletin (SAIB) warning aircraft owners and operators with auto fuel supplemental type certificates (STC) to ensure the fuel they use does not contain alcohol (ethanol or methanol). The SAIB reinforces EAA’s ongoing efforts to ensure the availability of compliant autogas by heading off or modifying legislative attempts in several states to require ethanol in all gasolines sold.

EAA, one of two primary sources of automobile gasoline STCs for general aviation aircraft, advocates that, at the very least, states should exempt premium grade fuel from ethanol mandates to ensure a readily available and safe fuel supply for aircraft.

The FAA cites numerous reasons alcohol and airplanes do not mix. Alcohol:

  • Adversely affects the volatility of auto gasoline, which could cause vapor lock.
  • Is corrosive and not compatible with rubber seals and other materials used in aircraft, which could lead to fuel system deterioration and malfunction.
  • Is subject to phase separation, which happens when the fuel cools as an aircraft climbs to higher altitudes. When the alcohol separates from the gasoline, it may carry water that has been held in solution and that cannot be handled by the sediment bowl.
  • Reduces the energy content of fuel. Methanol has approximately 55 percent of the energy content of gasoline, ethanol 73 percent. More alcohol equals reduced range.

EAA’s auto fuel STC has saved aircraft owners untold thousands of dollars by allowing them to use auto fuel rather than more expensive avgas. The FAA recommends that owners use automobile gasoline that conforms to the specifications published in their airplane flight manual or automobile gasoline STC flight manual supplement. Those unsure about the presence of alcohol can perform a simple test with EAA’s auto fuel Alcohol Test Kit.


  • Order online here
  • Call EAA at 800-564-6322 for USA and Canada. Outside USA and Canada 920-426-5912 or Fax 920-426-6761
  • E-mail stc@eaa.org
  • Send check and money to:
    EAA Dept. MO
    PO Box 3086
    Oshkosh WI 54903-3086
  • E- mail membership@eaa.org  


  1. Add water precisely to zero level line on percentage alcohol scale on side of tester.
  2. Add fuel to be tested up to the gas level line.
  3. Cap with thumb or stopper provided, shake vigorously to thoroughly mix.
  4. Let stand 5-10 minutes, read percentage alcohol-in-fuel on scale of 0-30% at line separating gasoline and water.
  5. The gauge on the side of the tube will read percentage of alcohol in the tube.
  6. Anything above 1% would be cause for additional actions to be taken, see additional information located in the FAQs section under Alcohol Testing  for further information.


  1. Quik-Check is a highly concentrated non-toxic dye, so care must be taken to prevent staining of hands or clothing.
  2. A baby food jar or small jam jar with lids are great items for shaking up fuel and dye sample.  The fuel tester above may be used, but staining of the plastic will result if dye and gas are left in tube.
  3. Place 1 drop of Quik-Check Solution in a small fuel sample. 
  4. Easy to read blue test results. Quik-Check is only absorbed by water and alcohol, not petroleum/oil. Use alone or with a fuel tester. If there is no ethanol or water, the blue Quik-Check drops to the bottom and the fuel sample remains yellow.
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