The Eliminate Aviation Gasoline Lead Emissions (EAGLE) team has released Part 1 of a three-part series called “Clearing the Air: How Unleaded Aviation Fuel Is Gaining Approval.” Part 1 (attached below) is labeled “Understanding the STC process and why it matters to pilots and aircraft owners.” In a series of Questions and Answers, EAGLE attempts to clarify the differences between the Supplemental Type Certificate (STC) approval process as opposed to the Fleet Authorization protocol. Part 2 will further explore ASTM approvals through the Fleet Authorization process; followed by Part 3, which is tasked with explaining, “the importance of industry consensus standards, such as those from ASTM International.”
I learned early on in the aviation business one must be very careful in adopting new technology. The BD-5 is one example, another is the use of automotive conversions for aircraft. In my mind the same goes for the use of G100UL. I understand the attraction of the David and Goliath metaphor, but the fact is that there are real concerns about the use of G100UL across all piston aircraft of all ages. Ask yourself these questions. Why are Textron, Cirrus, Continental, and Lycoming all concerned about its use? Why is GAMI unwilling to support the pursuit of an ASTM specification? Does it strike you as strange that the FAA would grant GAMI an STC across all piston aircraft of all ages, when typically the process would be to develop an ASTM specification for the fuel first and then develop STCs on an aircraft by aircraft basis. What are the implications of using Xylene in G100UL? It is a known solvent for materials made of rubber. Why does G100UL discolor paint? Could that be because Xylene is a paint solvent as well. And consider this, the STC approval of mogas for the use in aircraft is limited in its application to those with low compression engines and often requires a modification for specific aircraft fuel systems for its use. How is it possible that GAMI, a relative new company to fuel development, can have managed to produce a fuel that checks the box for replacement across all piston aircraft of all ages with no modifications. I’m just saying, doesn’t that raise any issues in your mind?
Don’t get me wrong, I think GAMI is a great company, I have their matched fuel injectors in my Continental IO-520, but I’m not ready to put their G100UL in my 40 year old fuel bladders just yet. I think I’ll give it some time. California has always been a progressive state, I’m happy to let the beta testers and early adopters out there sort out the inevitable issues that will crop up with G100UL first.
I’ve read answers to all these questions. Why are we still asking them when they’ve all been broached many times before and are always answered with the same text? Not wanting to call anyone a Luddite but it’s getting harder not to.
I own/fly a Glasair II which is of composite construction. Vinylester resin and fiberglass (can’t remember if E glass or S glass). I think the vinylester resin is a Durakane 411-350 product. Over the years I’ve read a few documents and posed questions in a couple places asking if these unleaded fuels have been tested for compatibility with composites. I haven’t seen anything one way or the other. Maybe I’m not looking at the right things. Stuff like Xylene is a solvent/thinner for epoxies and resins. This has me greatly concerned.
Many composite aircraft manufacturers (i.e. Extra) have strong warnings against allowing fuel to contact the surface of the vehicle without immediately cleaning it up. I am sure the same will be true for G100UL. I checked FAQ - G100UL high octane unleaded avgas and they don’t make any specific mention of composite airframes. Send them a note and, please, share the answer.
Uh, Fact is GAMI has listed items in the ASTM standard that are not appropriate or needed in their technical judgement, and omissions (things that should be included).
Thus I consider your ‘unwilling’ to be a misleading statement, you are assuming something - why wouldn’t GAMI pursue certification to a proper standard?
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Hasn’t Swift also identified shortcomings in the ASTM standard?
New companies can be smarter than hidebound ones common in the industry. GAMI is not quite ‘new’ as you show by using its matched injector sets of fuel injectors which go back many years. Indeed, the company was founded in 1994 - that’s three decades ago. Braley was tinkering before that. General Aviation Modifications, Inc.