Last week, the Experimental Aircraft Association (EAA) weighed in on the controversy surrounding G100UL unleaded aviation gasoline from General Aviation Modifications Inc. (GAMI). As an advocacy group for Experimental-Amateur Built (E-AB) aircraft, among others, EAA’s statement focused on specific concerns for E-AB builders and operators.
How is it that now, after decades past beginning the process of replacing 100LL with 100UL, concern over sealants, gaskets, o-rings hoses, etc, dissolving, or, being compromised in a negative way, this concern has now come into focus? Decades pass and this has never been addressed with finality? This is now a concerning issue? I don’t get it. How can this be?
Wasn’t this much stink when Red disappeared and Green became Blue. But . . . no internet then. (grin)
@MrMilkshake, Because the components and additives to the base alkanes are determined by the formulation of the fuel. That is, each fuel that tries to cross the 100UL finish line has a unique formulation that needs to be tested against those sealants, gaskets,o-rings, hoses, etc. dissolving. New fuels can only be tested once they are ‘created’. So you can’t ‘address’ this up front. Finality means testing against the latest formulations as they are developed, until no problems surface.
Part 43 does apply to EAB aircraft. Each condition inspection must be signed off as being performed I/A/W the scope and detail of Appendix D.
I think the main concern will be with experimental aircraft that are made of composite material, though a large part of GAMI’s testing was done with their Cirrus.
In the case of E-AB aircraft, there would no practical reason for the G100UL powers that be to conduct extensive testing because part 43 does not apply to E-AB aircraft. E-ABs are not required to use TCd products and therefore the aircraft could be a grandma’s quilt creation making universal G100UL testing impossible.
Why is this so difficult? See C&EN: WHAT'S THAT STUFF? GASOLINE for a good description of how complex the formulations of our ICE fuels are.
TLDR:
In a nutshell, gasoline is a mixture of C4 to C12 hydrocarbons specially blended with a few additives to meet the performance needs of … engines.
That doesn’t sound too complicated, but in actuality gasoline is quite complex, consisting of several hundred compounds.
The composition of gasoline can vary widely depending on the blending specifications required….
That applies to the condition inspection only and who can perform it. Maintenance can be performed by anyone, certificated or not, and approved parts are not required. In fact, during the build process, using too many TCd components could render the finished aircraft as ineligible for an E-AB certificate.
Either braly is lying or that Mechanic is lying.
Cirrus doing an about face was shocking.
When we find out who the liar is, they need to be put into a cub and flown until they soil themselves… On video. Tired of all the bs.
I thought that was the reason for building experimental aircraft, to experiment with new products! Maybe after spending $150,000 some folks feel “uncomfortable” experimenting anymore? Has anyone asked George Brawley for his input about G100UL in these aircraft?
I’m an EAA technical counselor and I can tell you that there is a great deal of variety in materials and methods used in the construction of amateur built aircraft. It would be virtually impossible to test any new unleaded fuel across all the possible variations. The EAA, aircraft kit manufacturers, and amateur builders will just have to run their own tests to determine compatibility. Such is the way in the experimental aircraft world.
I fly an E-AB. I know that my aircraft should fly a little over weight. It should fly with the CG a little outside of limits. And if need be, it should fly with a fouled plug. I also believe that the components used in the fuel system should be compatible with any number of alternative fuels. But in all cases - I am now the test pilot. The most telling line in the story is: “to date a list of materials tested has not been shared with owners and operators”. In my mind, transparency is paramount in generating trust in the product and the provider. Personally, I will let the bolder pilots be the first adopters - especially when I fly with family in the plane. But that’s just me.
I have never taken the time to understand what variant of composites the Cirrus is constructed from. Probably epoxy in conjunction with carbon fiber and/or fiberglass and foam core. My Glasair is built with Vinylester resin and fiberglass. I will not experiment with a fuel other than 100LL until I know for a fact that a replacement fuel will not damage the structure or send some kind of goo through the fuel system.
The FAA has provided an overview of the test plans and list of materials (significant amount) that are being tested as part of the PAFI Testing of the Lyondell/VP Racing Fuel. It appears that many of the components have been provided by the E-AB Community.
The information can be found at Resources | EAGLE under the FAA section. They are entitled Materials Compatibility Test Plan, PAFI Materials Compatibility Test Pan (PAFI-MTP-002) and Materials Test Matrix. The Materials Test Matrix list hundreds of materials including paint systems, sealants, fabrics, distribution systems, fuel bladders, composites, etc.
The website also provides an overview and update on the entire testing program including engines and airframes that are being evaluated.
Because there is no standardized testing! STC tests and materials are proprietary, as it said in the article, and so a lot has been missed! When is Braly going to wake up, put on the big boy pants, and get ASTM approval?
Can we please, please, please have access to G100UL without the additives? In other words, 94UL?
Hoses, gaskets, and other rubber materials were changed on autos for unleaded gas. The big concern nearly no one appears to talk about are aircraft engine exhaust valves. Only lead keeps the exhaust valves lubricated and prevents exhaust valve failure. In 4 cylinder aircraft engines, if an exhaust valve fails one is landing wherever they are or crashing. Having lost two exhaust valves 200 hours apart in the 1980s; the problem is front and center for me. Fortunately, my 1964 Cessna 172, 6 cylinders, flew acceptably on 5 cylinders allowing return to the airport. No substitute exists for lead lubrication of exhaust valves; no matter what the current avgas fuel manufacturers say. 240,000 aircraft below 12,500 pounds gross weight is infinitesimal compared to the billions of autos on Earth and why unleaded gas was needed for autos. But aircraft engines, not, not, not on unleaded avgas for safety for lubricating exhaust valves. The military will likely get a pass being allowed to use leaded gas which should also include the 240,000 general aviation aircraft. One large volcanic eruption places more lead in Earth’s atmosphere than all of these aircraft over any equivalent time period. The EPA did not consider the above facts in their endangerment finding making the EPA endangerment finding erroneous. The EPA endangerment finding for leaded avgas needs to be removed. Who will talk to the EPA and fix this situation? Remove the endangerment finding for leaded avgas. Government run amok again! Someone with some horsepower with the EPA should be able to get the leaded avgas fuel endangerment removed. Who knows the current EPA administrator appointed by Donald Trump? This person should be accommodating!
To which ASTM testing standards are you referring to? The testing of G100UL actually does follow many ASTM test standards. It’s just that the fuel itself does not have its own ASTM standard. There also is no such thing as “ASTM approval”.
That would be 100LL without the lead. My understanding is that G100UL is not 94UL plus octane-boosting additives.