Increased Focus on Leaded Fuel

EPA heightens its focus as general aviation searches for an alternative to leaded gas


The initial standard for lead emissions issued by the Environmental Protection Agency hasn’t changed since 1978; until now that is. Last year, the Friends of the Earth environmental group filed a petition with EPA requesting that lead emissions standards be proposed for general aviation aircraft to improve health protection for at-risk groups. Last month, after evaluating the science of lead and public comment on the issue, EPA published its final ruling to revise the National Ambient Air Quality Standards (NAAQS) for lead. The impact of the new standard on the general aviation community remains to be seen as alternatives to avgas don’t come easy, or cheap.

Lead has always been regulated by the EPA as a contaminant under the Clean Air Act as part of the National Ambient Air Quality Standards (NAAQS). When the orginal standard was set, states were required to measure local air quality near potential sources of lead emissions and, if the sources exceeded the allowable limit, action needed to be taken to reduce the emissions. This, in part, led to the ban of leaded automobile gasoline in 1996.

EPA recently reassessed all potential sources of lead emissions and the health impacts of lead in the local air quality. The reassessment led to the revision to NAAQS in October which tightened the amount of allowable airborne lead emissions by ten times, from 1.5 micrograms per cubic meter of air (ug/m3) to 0.15 ug/m3.

States have been required once again to measure lead levels near all potential sources which emit greater than one ton of lead per year as well as all population areas greater than 500,000.

Of the the many local sources identified by EPA, general aviation airports are considered one because of the use of leaded avgas (100LL) by piston-driven aircraft.

According to Walter Desrosier, VP of engineering and maintenance for the General Avation Manufacturers Association (GAMA), the key reason why lead was not banned from aviation when it was orginally banned from automotive use is that to date, no alternative to avgas is available, which presents significant safety problems for aircraft.

Owen Busch, vice president of supply and devolopment for Avfuel, an independent fuel supplier, echoes Desrosier’s sentiment.

“A replacement fuel cannot comprimise the safety of the aircraft; the industry doesn’t have the likley candidate in hand yet,” says Busch.

The National Air Transportation Association (NATA) says in its report to EPA, “Remove the lead, and aircraft will be made unsafe and unsuitable to fly. The usage of other fuel types will pose a very high risk on operational safety and is not recommended by aircraft engine manufacturers.”

Apart from developing and producing a viable alternative to leaded aviation fuel, steps must be taken first to determine just what kind of impact avgas has on local air quality.

Monitoring and Measuring
EPA has estimiated lead emissions for general aviation airports on the basis of the number of LTO (landing and take-off) cycles aircraft make. This determination for most planes is an overestimation since FAA data on LTO cycles per airport include aircraft fueled by both jet fuel and avgas.

Of 3,414 general aviation airports identified by EPA, only five were estimated as emitting more than the acceptable one ton of lead per year. These airports are Van Nuys, CA; Centennial, CO; Phoenix Deer Valley, AZ; Orlando Sanford, FL; and Daytona Beach, FL.

The EPA has set up specific benchmarks for the measuring of lead in the air. Including general aviation among other sources, EPA estimates that 236 new or relocated monitoring sites will be necessary to satisfy monitoring requirements. Half of all newly required monitors are to be operational by January 1, 2010, with the other half operational by January 1, 2011.

By June 2013, states must submit reports to the EPA outlining steps planned to be taken in order to reduce lead emissions should local air quality be in violation of EPA standards. By January 2017, states must measure again to show that they have successfully reduced lead emissions to meet NAAQS.

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