By Joseph E. (Jeb) Burnside
July 29, 2013 - Despite the wide variety of innovative aircraft at EAA Oshkosh 2013, most share one thing: They consume fuel. Of the three basic fuels commonly used by general aviation - 100LL aviation gasoline, Jet A and unleaded gasoline - only one of them contains tetraethyl lead (TEL), a toxic substance long ago removed from automotive gasoline. That fuel is, of course, 100LL, and its lead content is an ongoing health, environment, and economic issue, which means it eventually will be replaced.
But with what?
There simply isn't a current substitute for 100LL that works for the existing fleet of GA aircraft. A large number of certificated and experimental aircraft are operating just fine on unleaded automotive gasoline - for 30 years. For a significant portion of the fleet, however, mogas as it's called simply doesn't have sufficient anti-knock characteristics - among other issues - to allow safe, efficient operation. And given the sorry state of new piston-aircraft sales - at least compared to 10 or so years ago - the existing fleet is the market for 100LL and its successor.
Although industry and the FAA have known for some time that 100LL's days are numbered, when and how the fuel is replaced, and with what, remain unanswered questions. Those questions also mean there's significant uncertainty on the potential impact replacing 100LL could have on the future of general aviation.
After some not-so-gentle prodding from health and environment groups, plus the U.S. Environmental Protection Agency, the FAA and industry are working together to find the answers. Most recently, acting on industry recommendations, the FAA initiated an unleaded avgas program and created a new office to manage all fuels-related testing and certification issues, among other challenges.
But the basic problem remains: Coming up with a replacement for 100LL isn't as simple as just removing TEL.
Consider: If lead is removed from 100LL, something has to take its place. Many substances are available with high octane qualities, but there's no free lunch: Altering one component of the 100LL "recipe" - also known as ASTM D910 - to eliminate lead easily can impact the fuel's other characteristics, perhaps increasing its ability to absorb water, promote corrosion in fuel systems, or dissolve rubber fuel bladders.
And from a consumer perspective, one of the most important characteristics a 100LL replacement should have is reasonable cost. Removing TEL and replacing it with some exotic substances could mean avgas's already too-high cost could climb further.
No one wants that.
Another issue is certification. Many non-experimental aircraft are certificated to operate on 100LL. If 100LL isn't available, what then? Put another way, what's the legality of operating an aircraft certificated to use 100LL on an unleaded 100 octane fuel?
At a minimum, it may require securing from the FAA an expensive and time-consuming STC for each and every make/model airframe and engine. The testing necessary to obtain an STC may result in new limitations or require component replacement, further increasing the cost.
There needs to be an efficient and effective means for FAA fleetwide certification approval for a replacement unleaded fuel that meets all the necessary safety requirements.
These are just a handful of the challenges facing industry and the FAA as the search for a 100LL replacement gets better organized. Resolving them is one result of ongoing efforts by industry's alphabet soup, including the EAA, to ensure general aviation's future.
Those efforts follow a monthslong effort by industry known as the Unleaded Avgas Transition Aviation Rulemaking Committee, or UAT ARC, which the FAA chartered in January 2011. In addition to EAA and various FAA offices, UAT ARC's membership included the Aircraft Owners and Pilots Association (AOPA), the General Aviation Manufacturers Association (GAMA), the National Air Transportation Association (NATA), Cessna, Cirrus, Continental, Lycoming, the American Petroleum Institute, the EPA, ExxonMobil, Shell, Swift Fuels, and General Aviation Modifications Inc. (GAMI).
Thirteen months later, in February 2013, the UAT ARC produced a 99-page report to the FAA, noting the many challenges the agency and industry face before a 100LL substitute can be in wide use. In addition to the issues discussed above, the UAT ARC's report also identified as major obstacles the lack of a program leading to fleetwide evaluation, certification, and deployment of a 100LL replacement; inadequate market forces, a product of general aviation's relatively small size; and no standardized policy or test procedures enabling fleetwide assessment and certification.
Additionally, the UAT ARC made five key recommendations to the FAA. They include: develop a roadmap and identify milestones for a 100LL replacement development process; establish centralized and standardized testing of candidate fuels, including generation of fleetwide certification data; create a solicitation and selection process for candidate fuels; establish the Piston Aviation Fuels Initiative (PAFI) - a collaborative industry-government initiative - to implement the UAT ARC recommendations with minimal impact on the existing piston-engine aircraft fleet; and an FAA centralized certification office for all fuel-related programs.
And the FAA has reacted.
Most recently, the FAA announced it would begin laboratory tests of candidate fuels in 2014, and asked producers to submit appropriate samples. The agency's goal is to have at least identified the most viable replacements for 100LL by 2018.
In addition to establishing a test program, the agency established its Fuels Program Office, AIR-20, to provide focus and consolidate resources and expertise. Also in response to the UAT ARC's recommendations, the FAA and the General Aviation Avgas Coalition, an industry group, formed the PAFI Steering Group (PSG) and are working together to implement the recommendations.
"We believe that the FAA's program is by far the most effective process to not only evaluate the fuels but give the industry the data it requires to actually bring a fuel to market and implement it across the entire GA fleet," EAA Chairman Jack Pelton said in June when the FAA's testing program was announced. "We are excited to see what fuels are brought forward for consideration and look forward to FAA being able to evaluate them in such a way that all interested parties in the industry can collectively and knowledgeably determine the best long-term outcome for general aviation."
AOPA President Craig Fuller also voiced his organization's support for these efforts. "We are pleased that the FAA is continuing to take concrete steps to help the aviation industry move forward with the testing and evaluation of promising avgas alternatives. We understand the complexities of this search, and we are confident that diligent work will help us find an acceptable fuel source that is safe for pilots, the public, and the environment," Fuller added.
Throughout the week at AirVenture 2013, several scheduled presentations will update attendees on various aspects of the search for a 100LL replacement.
The important takeaway?
Unlike in previous years, there's finally a workable plan to which the FAA and industry have agreed, one designed to consider the technical, operational, and economic challenges ahead with a program aimed at identifying the most viable replacements for 100LL by 2018.