Origins of the 100LL replacement crisis

According to AOPA Online click here, Congress enacted the Clean Air Act of 1970 and shortly after created the Environmental Protection Agency (EPA). In 1978 the EPA established a National Ambient Air Quality Standard for lead. …In the 1970s, EPA set national regulations to gradually reduce the lead content in gasoline. By 1996, EPA promulgated regulations that banned the use of leaded gasoline in highway vehicles.

The EPA is now forced to act, due to pressure such as “PETITION FOR RULEMAKING SEEKING THE REGULATION OF LEAD EMISSIONS FROM GENERAL AVIATION AIRCRAFT UNDER § 231 OF THE CLEAN AIR ACT” submitted by Friends of the Earth on October 3, 2006. See:

According to FAAST Blast Notice Number: NOTC2273 of May 06, 2010: On April 28, 2010, the Environmental Protection Agency (EPA) issued an advance notice of proposed rulemaking (ANPRM), the first step in a process that may lead to standards mandating GA’s transition to unleaded avgas. …Avgas is the only remaining transportation fuel in the United States that contains lead. …EPA estimates that lead emissions from aircraft using leaded avgas accounts for approximately half of the national inventory of lead emitted to air. EPA will accept public comment on the ANPRM until June 28, 2010.

Where is lead (TEL) still used in fuel? According to click here, Countries where Leaded Petrol is Possibly Still Sold for Road Use. As at 10th May 2010. Compiled by Robert Taylor, Researcher, The LEAD Group Inc. [LID 12714]

  1. Algeria
  2. Egypt
  3. Afghanistan
  4. Korea, Dem. People’s Rep of (N. Korea)
  5. Myanmar (Burma)
  6. Bosnia and Herzegovina
  7. Montenegro
  8. Kosovo
  9. Serbia
  10. Iraq
  11. Yemen

Who makes TetraEthylLead (CAS 78-00-2)?

Innospec IOSP on Nasdaq A Delaware, USA corporation. From their SEC form 10-K: “Our principal executive offices are in Ellesmere Port, United Kingdom. We became an independent company on May 22, 1998, when we were spun off from our then parent corporation Chemtura Corporation, previously known as Great Lakes Chemical Corporation. We changed our name from Octel Corp. to Innospec Inc. on January 30, 2006. On March 21, 2006 we transferred the listing of our common stock from the New York Stock Exchange (“NYSE”) to the Nasdaq Stock Market (“NASDAQ”).” …“Our Octane Additives business is the world’s only producer of tetra ethyl lead (“TEL”).”

Guiyang Yifeng Fine Chemical Co., Ltd Zhazuo, Xiuwen, Guiyang, Guizhou, China. From their information on “The company was estasblished in 2005. Guiyang Yifeng Fine Chemical Co., Ltd is a new Chemical Company specially manufacturing Tetra Ethyl L Lead. Our output is 3000MT per year including TEL-CB (used for autos) and TEL-B (used for aviation) . We are the biggest producer of Tetra Ethyl Lead in the world at present time. Meanwhile, we are the only one legal manufacturer of this commodity in China. …Any end users or dealers are welcome to contact with us”

Chenhaibin Rm2203, Bldg.4, No.88 Jianguo Rd, Chaoyang Dist, Beijing City, China 1000, Beijing, China 100022. From their information on “Beijing Hua Di Union Investment Co., Ltd has invested RMB 70,000,000 (USD 9,000,000) to set up a manufacturing factory to produce the tetraethyl lead (tetraethyllead; lead tetraethyl;tetraethyl plumbane). There are 25000 square meters in the whole land of the factory. There are more than one hundred employees is the factory. Five of them are senior engineers and eight are engineers. We are a high technical and professional team in the field of producing the tetraethyl lead in China. The product of the tetraethyl lead can improve the work efficiency of the engines of the motors and the aircraft. As an additive in the process of refining the crud oil, it can promote the octane value of the fuel. So far the products are sold to the United States, Southeast Asia, East Europe, Middle East and South Africa.”

Daqing TST Chemical Industry Co., LTD 49 Huagong Road, Xinghua Village, Longfeng district, Daqing, China, Daqing, Heilongjiang, China 163714. From their information on “Daqing TST Chemical Industry Co.,LTD is a manufacturer of tetraethyl lead in China. Tetraethyl lead output is 2000mt/year. Have two type of specification :TEL-B and TEL-CB . we can produce according to requirement of customer .We would like to establish business relations with company in the world. ”

About avgas: who makes it?

Annual US avgas consumption is about 186,000,000 gallons. That is less than 0.14% of the volume of automotive gas, and only .08% of total refinery volume:

According to the US Energy Information Administration, there are about 150 refineries in the US:

According to a Nov 1, 2007 article by Matt Thurber, only 4 companies made avgas:
click here.

The following avgas refineries are active in the US:

  1. Conoco Phillips: Sweeney, TX, Borger, TX, Billings, MT
  2. Chevron Texaco: Richmond, CA, Salt Lake City, UT, Pascagoula, MS, Hawaii
  3. British Petroleum: Toledo, OH
  4. Exxon Mobil: Torrance, CA, Baton Rouge, LA

What is 100LL, and why is it so special?

The properties of both Avgas 100 and 100LL are defined in ASTM D910. The current revision is 7a. It’s available for $38 from ASTM: Various labs offer testing services, to verify that a sample of fuel meets this spec. For an example, see: If you don’t want to spend $38, avgas vendors usually offer a tabulated characterization of their fuel in a format similar to D910. For example, see pages 8 and 9 of the Air BP Handbook of Products.

Thus, ASTM has created a fuel specification; history has proved that this fuel is good for airplane engines. Engine manufacturers have long specified that this fuel be used in their engines.

The problem is that, despite more than 20 years of trying, nobody’s been able to meet all the requirements of ASTM D910 without TEL. The assumption that D910 must be met has paralyzed efforts to produce a substitute unleaded avgas.

Over the years, many industry committees have been formed, and many meetings have been held. Most recently, according to a June 25, 2010 article: click here. a new Industry Avgas Coalition has been formed; members are the GA advocacy groups:

  1. EAA (Experimental Aircraft Association)
  2. NBAA (National Business Aviation Association)
  3. AOPA (Aircraft Owners & Pilots Association)
  4. GAMA (General Aviation Manufacturers Association)
  5. NATA (National Air Transport Association)
  6. API (American Petroleum Institute)
  7. NPRA (National Petrochemical & Refiners Association)

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. Their 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.

Sadly, FAST is another cruel oxymoron. The inability of aviation interest groups to provide a solution has spawned an “I’m mad as hell, and I’m not going to take this anymore!” movement. One example is the Clean 100-Octane Coalition; see their website

Fortunately, while alphabet soup groups have been wringing their hands others have been working to solve the problem.

Unfortunately, several solutions are being pursued and none satisfies everybody.

One solution is 94UL fuel, which is 100LL without TEL. Some call it “white gas”. Using it in an 8.5:1 C.R. engine requires compression ratio reduction, or ignition retard; both mean power reduction. Owners of lower-performance engines (C.R. already less than 8.5) are happy with this solution. So is TCM; they want to offer a compression reduction kit for existing engines, or replacement engines that recover power by increased displacement or turbocharging. Paul Bertorelli is editor of Aviation Consumer magazine; he’s long been following the 100LL replacement issue. Listen to his podcast interview with Bill Brogdon of TCM:

The 94UL solution is opposed by the Clean 100-Octane Coalition. They represent the “20% of airplanes that burn 80% of the avgas” and they need at least 100 octane. Lycoming also opposes it; although engines with electronic ignition improvements such as knock sensor-imposed ignition retard can tolerate lower octane fuel, it always means power reduction. Lycoming is pushing for a full 100 octane replacement; listen to Paul Bertorelli’s podcast interview with Michael Kraft of Lycoming: click here.

Two companies are testing unleaded avgas with octane ratings of 100 or more:

Swift Enterprises has been working since 2005. A patent application has been filed. Their original efforts derived from biomass feedstocks. Recently, they’ve announced that they can also derive from natural gas. Their fuel, now called UL102, is heavier than 100LL; it’s about the density of jet fuel. They’ve finished extensive testing at the FAA’s Wm. J. Hughes Technical Center, and they’re into an STC program with Embry Riddle. ASTM specification of UL102 is underway. For more, listen to Paul Bertorelli’s July 2, 2010 interview with David Perme, Swift’s CEO: click here.

GAMI, the people who brought us custom-tuned fuel injectors, has recently begun an effort. The composition of their G100UL fuel is secret. Their fuel is made from materials “already inside the fence of existing refineries”. Their fuel is also heavier than 100LL, although their numbers claim it’s lighter than UL102. Engine testing has been at their own facility. They have just recently applied for an ASTM standard. Cirrus is interested in working on an STC with them. For more information, listen to Paul Bertorelli’s July 2, 2010 interview with George Braly of GAMI: click here.

I’ve recently written an article summarizing Swift’s efforts. See the next 2 pages.

“Swift Fuel” is now UL102

According to their president Mary Rusek, Swift Enterprises ( has been developing an unleaded replacement for 100LL since 2005. Their early fuel formulations were multi-component, and some of those components were petroleum derivatives. Since 2007, they’ve settled on a primarily two-component formulation codenamed “Swift 702 fuel”. 702’s two main components, mesitylene (1,3,5-trimethyl benzene) and isopentane (2-methyl butane), can be derived from biomass. Thus, 702 can be made from completely renewable resources as described in Swift’s most-recent patent application ( The ASTM taskforce recently agreed to the designation UL102 to fit into the new ASTM nomenclature; it has a minimum octane rating of 102, compared to the 99.6 rating for 100LL under ASTM D910.

According to Dave Atwood’s report DOT/FAA/AR-08/53 issued in January of 2009, he and other researchers at the FAA’s William J. Hughes Technical Center “performed detonation and power performance tests on the Swift 702 fuel as compared to a locally purchased 100LL in two of the highest octane requirement engines in the fleet. A Lycoming TIO-540-J2BD and a Lycoming IO-540-K were evaluated on both fuels… Any fuel satisfying the octane requirement of these two engines would satisfy the octane requirement of the majority of the piston, reciprocating engine fleet… The Swift 702 fuel had a motor octane number (MON) of 104.4, as determined by the international standard test ASTM D 2700, and the locally purchased 100LL had a tested 103.6 MON… A power baseline and detonation test was run in the IO-540-K engine, comparing the performance of the Swift 702 fuel to 100LL fuel, and a detonation performance test was run in a Lycoming TIO-540-J2BD engine… At all engine speeds and manifold pressures, the Swift 702 fuel produced more than 98% of the horsepower as the 100LL and produced an average increase in EGT of approximately 50°F… The Swift 702 fuel met most of the current leaded aviation gasoline specification ASTM D 910, except for the 50%, 90%, end distillation points, and heat content… and outperformed the 100LL in detonation testing… Further endurance testing is required to determine the significance of operating with 50°F higher EGTs… Future full-scale engine endurance tests will verify whether there will be issues with oil dilution, nozzle and fuel system deposits, bearing failure, induction varnish buildup, or cylinder and valve deposits from using Swift 702 fuel.”

Aside from octane rating, there are two other significant differences between UL102 and 100LL. One is that UL102 weighs more; its density is about the same as jet fuel. Like jet fuel it also has greater per-volume heating value, although the per-mass heating value is slightly less. As Dave explained in his January 2009 report, “The Swift 702 fuel was roughly 1.01 lb/gal heavier (or 17.5%) than the 100LL at 87°F. However, since the Swift 702 fuel had 96.3% of the energy density on a mass basis as the 100LL, the Swift 702 fuel has approximately 13% higher energy per gallon of fuel than 100LL. On a fuel mass flow basis, the Swift 702 fuel will produce slightly less power than the 100LL; however, on a fuel volume flow basis, which is typically more of a concern to a pilot, the fuel will produce more power than the 100LL. Therefore, the same number of gallons of fuel will weigh more for the Swift 702 fuel than the 100LL, but will provide a greater range of flight.”

The other main difference between UL102 and 100LL is vapor pressure, or volatility. Avgas must be volatile enough for good vaporization when starting an engine at low temperatures, yet not so volatile that it boils easily at altitude. These characteristics were not investigated in the testing summarized in the January 2009 report. As Dave Atwood stated, “The Swift 702 fuel did not meet the 50%, 90%, or end point of the distillation curves. This was due to the high aromatic hydrocarbon content of the fuel. Previous and extensive FAA tests determined that an unleaded fuel could meet the current detonation performance of the current ASTM D 910 100LL leaded aviation gasoline only if it contained at least 10% of a specific aromatic amine or it contained a very high concentration of aromatic hydrocarbon. In either case, it is highly unlikely that any such fuel would meet the distillation specification for an aviation alkylate-based fuel. Further tests are planned on the Swift 702 fuel using two separate high-power engines, a Continental and a Lycoming, for long-duration tests.”

The full-scale engine endurance tests Dave mentioned have been completed. A report is being written and should be available around 7/19/2010; look in: for DOT/FAA/AR-10/13 “Full-Scale Engine Endurance Test of Swift Enterprises UL102 Fuel” by D. Atwood.

Given differences in aircraft weight & balance, flying range, and possibly different starting procedures in cold weather, an STC looks like one way for a certified aircraft to use UL102. In a joint project with Swift Enterprises, Pat Anderson of Embry-Riddle’s Eagle Flight Research Center in Daytona Beach, Florida is now doing certification testing for an STC allowing use of UL102 in its fleet of 172s; see After a little more than 40 hours of initial testing on their Piper Seminole, Pat has noticed only two problems. One is relatively hard starting at temperatures below 30 degrees F; this may be related to the fuel distillation curve differences vs. 100LL, as mentioned by Dave Atwood. Swift is working on that now. The other is that an engine adjusted to idle properly on 100LL will idle rough and emit black smoke on UL102; a clean idle is achieved by manually leaning the mixture during ground operation, which is good practice even when using 100LL.

According to Pat Anderson, STC certification testing must be done with normal volume-production fuel, rather than with laboratory-prepared samples. This creates a chicken-and-egg situation; it’s difficult to invest in a volume production plant without the STC-enabled markets.

An additional problem is that, using unoptimized processes and without economies of scale, early quantities of UL102 will probably be expensive. Fortunately, UL102 can be blended in any ratio with 100LL.

Swift Enterprises will give five presentations at EAA’s AirVenture Oshkosh 2010 in the Learning Center and the Forums Plaza, covering their fuels and fuel cells. Check the AirVenture forums schedule for times and places. Swift representatives will be in Embry-Riddle’s booths 397 to 401, adjacent to Aeroshell Square and also in the Learning Center.

Visit Swift’s website. Attend their forum. Stop by, and talk to them. If you, like me, see UL102 as a way to continue flying the airplanes you love, see what you can do to help.

7/7/10 by Curt Nehring
EAA 683629