Ethanol Considerations and The Future of Aviation Fuels

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Ethanol Considerations and The Future of
Aviation Fuels

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• The fuels we will use today and in the future
  will not be the same as the ones we used even
  last year.
• Automobile gasoline formulation is changing
  greatly
• 100LL will be a fuel of the past, just as leaded
  automotive gas is today

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• WHAT ARE SOME OF THE REASONS FOR CHANGE?

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• The mandated use of Ethanol has increase greatly
  in the US and is now being required in European
  auto gasoline's.
• There is significant pressure throughout the
  world to find alternatives to gasoline and jet
  fuels.
• There is only one supplier of tetra ethyl lead
  left in the western world
• Leaded automotive fuels are no longer used in,
  North America, Europe, Australia, New Zealand and
  some parts of South America, Asia and Africa.

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• Starting in 2000 North American , European,
  Japanese and Korean new car production became
  exclusively unleaded vehicles.
• World wide use of 100LL is declining, causing
  production and distribution costs to rise
• EPA wants eventual end to use of leaded fuel

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One hand gives the other takes away

• Last year the government
• Removed the oxygenate requirement for
  reformulated fuels (Meaning Ethanol was no longer
  mandated in reformulated gasoline)
• Added a requirement that a minimum amount of
  ethanol be used gasoline sold in the US
• The result is that more automotive gasoline
  contains Ethanol than ever before.

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What are the Issues with Ethanol?

• Engines
• For most non-injected aircraft engines there are
  no major issues.
• Airframes
• Most if not all aircraft fuel systems have major
  issues with fuels containing ethanol.
• FAA says do not do use it.
• SAIB CE-07-06 October 27, 2006

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ENGINES

• Common misconception that aircraft engines in
  general have problems with gasoline's that
  contain ethanol
• Use of ethanol in gasoline does pose material
  compatibility issues for some fuel injection
  components
• Fuel flow is a significant issue as it must be
  increased as the amount of ethanol added
  increases
• Oil washing is a concern particularly for
  engines that are not operated for extended
  periods of time.
• Accumulation of water in engine crankcase an
  issue for two stroke engines that are not
  operated often.

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AIRFRAME

• Material compatibility ethanol
• Vapor Lock
• Phase separation
• Water
• Temperature
• Octane lost (leading to detonation)
• Material compatibility with water/ethanol mix
• Cleaning

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The FAA cites numerous reasons alcohol and
airplanes do not mix. Alcohol

• Adversely affects the volatility of auto
  gasoline, which could cause vapor lock.
• Is corrosive and not compatible with rubber seals
  and other materials used in aircraft, which could
  lead to fuel system deterioration and
  malfunction.
• Is subject to phase separation, which happens
  when the fuel cools as an aircraft climbs to
  higher altitudes. When the alcohol separates from
  the gasoline, it may carry water that has been
  held in solution and that cannot be handled by
  the sediment bowl.
• Reduces the energy content of fuel. Methanol has
  approximately 55 percent of the energy content of
  gasoline, ethanol 73 percent. More alcohol equals
  reduced range.

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Effects of Ethanol takes time

• No not think you are OK just because you have not
  had a problem yet.
• Except for vapor lock ethanol related issues
  occur over time

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Ethanol

• Autogas is generally sold with 10 or 85
  ethanol.
• For conventional type certified aircraft testing
  has indicated that 3 ethanol is the maximum an
  aircraft system can safely handle.

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What should you do

• Always test for Ethanol
• Do not store fuel for long periods
• When you buy it use it
• Do not store fuel in metal containers
• If you do not have a sump drain add one
• Use your sump drains
• Consider using an aircraft style gascolator
• Experimental and LSA aircraft can mix 100LL and
  autogas to reduce percentage of ethanol
• Follow additional maintenance schedule for ROTAX
  engines using a leaded fuel

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Testing for Ethanol

• Using a glass or chemical resistant plastic (such
  as TPX) container, mark ten equally spaced
  volumes. A graduated cylinder is ideal however,
  a non-tapered glass jar, such as a large (quart)
  olive bottle, will work. 
• Add one part water (approximately 100 ml) into
  the container, fill to the first mark, and then
  add nine parts (approximately 900 ml) of
  automobile gasoline, fill to the top mark. Shake
  thoroughly, let stand for 10 minutes or until
  automobile gasoline is again bright and clear.
  Mark the apparent level of the line between the
  automobile gasoline and water.
• If alcohol is present, the water will absorb it,
  and the amount of water will appear to increase.

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Fuel Test Kit (15 from EAA)
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• When you start talking numbers at the end of the
  presentation it can be a little confusing. Like
  91/97, 98-108 MON, 91 grade, 87 UL mean what,
  octane, MON, RON, AKI. You know this all get a
  little confusing. Another question you might
  face is I have a 912, Rotax says when using 100LL
  you have increased lead deposits which are bad,
  what is the lesser of 2 evils, using autogas with
  alcohol or using 100LL? That is a tough one that
  you can not answer but I have had that question
  over the phone. Some of the ultralight/light
  plane fuel tanks are fiberglass with polyester
  resin and the alcohol is a real problem for
  these. Suggestion for those that have no choice
  but to use alcohol autogas is to completely
  disassemble and inspect/clean/replace as
  appropriate, fuel system every 6 months. Another
  suggestion for 2-cycle engines is to use mineral
  based oil instead of synthetic based oil.
  Mineral based oil is typically 501 where as
  synthetic is 1001, twice as much mineral oil
  coating internal engine components while the
  engine is in the hangar. Also, mineral based oil
  clings better to surfaces, synthetic has lower
  coefficient of friction and will not cling to
  part as well, when the engine is in the hangar.

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What is in the future

• Regular autogas will continue to have high levels
  of ethanol
• Unleaded Aviation fuels have been developed
• Market place will drive changes
• LSAs are starting to be a market factor
• Increased use of jets putting pressure on
  remainder of fleet to transition to unleaded fuel

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Who are the Players

• ASTM International is involved with writing the
  new fuel specifications
• The Coordinating Research Council (CRC) is
  helping organize basic research on new fuels
  components

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• The same organizations belong to both ASTM and
  the CRC fuel groups
• EAA, FAA, ROTAX, Cessna, Ethyl, ExxonMobil,
  TEXACO, Philips, AIRBP, and Chevron are currently
  the most active participants
• Recently proponents for an Aviation E85 fuel have
  also become much more engaged

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• Fuel components being examined as a replacement
  for lead include-Ethers (MTBE, ETBE)-Amines
  -MMT (Ethyl corp)-Ethanol

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A Short lesson on Numbers

• AKI, MON, RON, Rich Ratings, 100/130, 80/87,
  82UL, 100LL
• What does all this mean to you?

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• HOW MUCH TIME DO WE HAVE UNTIL WE SEE THESE NEW
  FUELS?

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• No one knows for sure
• 82 Grade is available
• 91/98 Grade Aviation Gasoline can be made
  unleaded
• Autogas is no longer the safe alternative for the
  low end of aviation (ultralights, homebuilt,
  Katana type trainers)
• 100LL will go away

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WHAT HAS BEEN DEVELOPED TO DATE?
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• A Swedish refiner is selling 91/97 unleaded
  aviation gasoline
• Oil companies have unleaded test fuels available
  in the 98 to 108 MON range
• GAMI is developing engines controls they hope
  will allow the most demanding opposed engines to
  operate on 91 grade fuel
• Cessna has successfully developed and flight
  tested a ETBE fuel.
• E85 Ethonal based fuel has been STCed.
• EAA, Cessna and ROTAX working on a new 87 UL
  aviaiton gasoline based on premium autogas.

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References

• EAA autogas STC website www.aviationfuel.org
• EAA SPORT PILOT MAGAZINE
• June 2006 Power On Ethanol and Rotax Engines by
  Phillip Lockwood.

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