Final Product "Must" Be A Drop-In Replacement For 100LL

By Tom Patton, ANN News Editor

A lot of pilots remember when 100 octane avgas was just that. Lead in fuel was little more than something we knew about, but as long as the engine ran, there wasn't much more to think about.

But when the push to unleaded fuel for cars began back in the 1970's, we all started hearing about, and eventually using 100LL avgas. The amount of lead was reduced in an effort to lower the amount of airborne lead pollution in the air. The 100LL transition went fairly smoothly, and the reduced amount of lead seemed to make little difference to the Lycomings and Continentals powering the majority of the GA fleet.

Now, with more stringent clean air mandates, the next transition is upon us, and a consortium of industry groups is working towards making the switch to a completely unleaded aviation fuel as transparent as the change to 100LL. But at the moment, there is no clear path to an unleaded aviation fuel that does not extract a significant penalty in engine performance.

In an online media briefing called by the Industry Avgas Coalition, the members said that the path to a solution on the issue is one that ensures continued availability of 100LL until a replacement solution is implemented that minimizes potential impacts of EPA actions upon GA. They call for a government/industry program for the development of an unleaded avgas, FAA leadership to ensure safety and establish appropriate airworthiness and lead emissions standards, and a provision for the long-term viability and safety of GA. The FAST (Future Avgas Strategy and Transition) Plan has been designed to identify the most viable unleaded solution possible to replace 100LL, and establish a transition timeline which addresses aviation safety, technical feasibility and impact upon the GA and avgas industries.

The coalition is made up of the GA advocacy groups EAA, NBAA, and AOPA, along with GAMA and NATA, and avgas production representative organizations API (American Petroleum Institute) and NPRA (National Petrochemical & Refiners Association). After testing more than 200 unleaded fuel blends, and full-scale engine tests on 45 high-octane unleaded blends, the Coordinating Research Council (CRC) unleaded avgas group, a collaborative research and testing effort among fuel producers, GA manufacturers, FAA, AOPA and EAA, concluded that there is no direct drop-in replacement for 100LL fuel. While the performance drops will be most significant in high-performance and turbocharged engines which make up only about 30 percent of the fleet, those users consume about 70 percent of the avgas used in the country each year, so a direct replacement that requires no engine modifications is critical.

The matter is compounded by the fact that avgas accounts for only 0.1% of all transportation fuel. It is very much a niche market that requires long term storage. Neither airports or refiners have the infrastructure to operate a "dual fuel" transition as happened when cars went from leaded to unleaded gas.

States are required by the EPA to meet National Ambient Air Quality Standards (NAAQS) for Lead of 150 ng/m3 by 2017. This takes into account all forms of lead pollution, but it could mean that piston engine aircraft operations could be restricted in densely populated areas, and would require a significant effort on the part of the GA community to sway public/political support to maintain GA airports.

The coalition, and in fact the GA community at large, understands that lead is harmful to humans. So taking part in the effort to resolve this issue is certainly important to those who fly. And the coalition agrees that the day of reckoning is coming, with only one supplier of the tetra-ethyl-lead (TEL) additive and a decreasing demand for leaded auto fuel.

The concerns go beyond engine performance. Safety must be considered as well. EAA's Doug McNair said that the FAA certifies engines with a specific fuel, and that high performance engines/aircraft require 100 octane fuel for detonation (“knock”) protection. But the 100LL ASTM D-910 standard includes many performance requirements necessary for safety, including octane, vapor pressure, distillation curve (cold/hot and high altitude operations as well as starting ability), freeze point, water separation, and long-term stability.

Walter Desrosier, Vice President Engineering & Maintenance, GAMA, said the effort will have to be driven by the FAA. He said that it will require FAA support in everything form R&D to certification, and that the approval/certification range to change the standards for every engine is unprecedented for FAA.

The coalition has resolved that GA industry stakeholders should work proactively to recommend that EPA and FAA promulgate regulations to reduce lead emissions from GA aircraft along a transition timeline which balances environmental benefit with aviation safety, technical feasibility and impact upon the GA industry. The goals should be to:

• Establish a process to develop the most viable unleaded solution to replace 100LL.
• Incentivize development of high-octane unleaded avgas.
• Recommend defined dates for transition to unleaded fuel.
• Minimize impact of EPA NAAQS for lead and endangerment finding under the Clean Air Act.

They see a short term transition period in which the CRC research report, due September 2010, determines how much reduction in maximum TEL content is possible to make an interim, lower-lead fuel completely drop-in ... no actions needed by operators ... with the introduction of a lower-lead content 100LL Fuel by 2015. They look for EPA and FAA regulation to mandate introduction of lower-lead fuel.

In the longer term, the coalition says that a public/private partnership should be established to develop the most viable unleaded solution to replace 100LL avgas and appropriate airworthiness and emissions regulatory standards; that FAA must take a leadership role in the integrated avgas program; that criteria for development of viable unleaded avgas specification be identified; and that unleaded avgas be developed with the support of that partnership.

The comment period on the EPA's ANPR on lead emissions from GA aircraft published April 28, 2010 has been extended until August 27th. AOPA's Rob Hackman said the coalition group met with the FAA Wednesday, and they are working to evaluate the avenues to get a safe product into aircraft. The FAA is looking at all certification avenues including STC, balancing safety with process. Doug McNair said that the coalition is not in the business of picking winners and losers in the fuel replacement game, but that assuring that there is a level playing field so that everyone with a possible solution is evaluated in the same way. Good data is critical to the process, he said.

The coalition believes that the 91/94UL scenario is worst case. 94UL is simply 100LL without the lead additive, which is what boosts the octane rating 6 points. While it is "drop-in" for 70 percent of the fleet, it is unworkable for that 30% of high-performance airplanes that consume 70% of the fuel. Meanwhile, you can be sure that there will be plenty of discussion on this topic at Airventure next month, and indeed in the months and years to come.

FMI: www.aopa.org, www.eaa.org. www.nbaa.org, www.gama.aero, www.nata.aero, www.api.org, www.npradc.org