By AOPA ePublishing staff
If you have received a supplemental type certificate (STC) to operate your airplane using auto gas in addition to avgas, you need to be aware of the potential hazards posed by “oxygenated” fuel.
“Usually when fuel is labeled ‘oxygenated,’ it means the gas is blended with ethanol,” explained Craig Brown of AOPA’s Pilot Information Center. Ethanol-blended fuel can damage fuel cells, O-rings, gaskets, and other rubber parts. It can also absorb water, leading to corrosion or forming ice crystals that obstruct the fuel system. Water absorbed by the fuel cannot be detected by sumping the tanks.
Many states now require the blending of ethanol in gasoline, but not all blended auto gas is labeled, so you can’t rely on information provided at the pump. Simple procedures and test kits are available to test fuel for the presence of ethanol.
In October of 2006, the FAA issued a special airworthiness information bulletin, addressing the airworthiness concerns of ethanol blended with auto gas for general aviation use.
“The bottom line is simple,” Brown said. “If you are using an auto gas STC, you need to check every batch of auto gas you purchase before you put it in your aircraft.”
December 19, 2007