The Federal Aviation Administration (FAA) this week put out a call to fuel producers to offer options that would safely let general aviation aircraft stop using leaded fuel by 2018.

The FAA says there are approximately 167,000 aircraft in the United States and a total of 230,000 worldwide that rely on the current 100 octane, low lead fuel for safe operation. It is the only remaining transportation fuel in the United States that contains the addition of tetraethyl lead (TEL), a toxic substance, to create the very high octane levels needed for high-performance aircraft engines. Operations with inadequate octane can result in engine failures, the FAA noted.

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The FAA said it wants the oil producing industry to submit fuel option proposals by July 14, 2014 that would wean those aircraft to unleaded fuel. The FAA said it will assess the viability of candidate fuels in terms of their impact on the existing fleet, their production and distribution infrastructure, their impact on the environment and toxicology, and economic considerations.

By Sept. 1, 2014, the FAA will select up to 10 suppliers to participate in phase one laboratory testing at the FAA's William J. Hughes Technical Center. The FAA will select as many as two fuels from phase one for phase two engine and aircraft testing. That testing will generate standardized qualification and certification data for candidate fuels, along with property and performance data. Over the next five years, the FAA will ask fuel producers to submit 100 gallons of fuel for phase one testing and 10,000 gallons of fuel for phase two testing.

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The FAA says it has already tested over 279 fuels in an attempt to find what it calls a "drop-in" alternative lead fuel solution, which would require no aircraft or engine modifications. "This week's request however responds to an Unleaded Avgas Transition Aviation Rulemaking Committee report to the FAA, which noted that such drop-in unleaded replacement fuel is unavailable and may not be technically feasible," the FAA stated.

The FAA says a new plan called the Piston Aviation Fuels Initiative (PAFI) will facilitate the development and deployment of a new unleaded avgas with the least impact on the existing piston-engine aircraft fleet. The FAA and industry-group leaders also recently formed the PAFI Steering Group (PSG), to facilitate, coordinate, expedite, promote and oversee the PAFI.

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