So, Why Do We Need EAGLE And ASTM, Anyway?

News Discussion
41

That’s true, but not for the reasons people may think.

The damage was likely due to too low an octane rating, not lack of lead.

When lead was added to gasoline, achieving the octane rating posted on the pump was easy. In fact, the gasoline being dispensed often had a higher octane, sometimes 1 or 2 points higher. So an “87” octane gasoline was really “88” or even “89”.

When lead was banned it became more difficult for refineries to meet, much less exceed, the posted octane. So what was once “88” or “89” is now exactly “87”, or even “86.9”.

The result was cars that formerly ran fine on “87” (which was really “89”) were now experiencing light detonation (“pinging”) far more frequently. Which can cause valve damage and valve-seat recession.

The UND experiment with unleaded avgas bears this out. First off, they didn’t use 100-octane unleaded avgas. They were using Swift’s 94UL with six points less octane. The engines they used are relatively high-compression (8.5:1) with advanced ignition timing of 25-degrees, both typical indicators of the need for higher octane. Originally certified for 91/96 avgas, they now show 100LL on their type certificate. In effect, they were being run right at the limits on 94-octane and some engines didn’t make it.

(as an aside - the Continental C-85, C-90, and O-200 engines like those found in Cessna 150s, Piper Cubs, etc. have a compression ratio of only 7:1. Their octane requirements are minimal. Those engines have been happily burning unleaded mogas for decades. Yet no one talks about a wave of valve-seat recession in those engines).

42

And don’t forget the addition of electronic ignition, knock sensors, lambda sensors, and all of the other modern stuff that prevents detonation. Too bad, but we don’t have any of those systems in our aircraft.

43

This is the crux of the entire matter. As @goldsternp says it plainly. Why simple when we can have complexity?
Transportation fuel is a means of storing energy in a very dense fashion, namely combustible/flammable liquids that turn into mechanical energy by converting the stored energy into heat. That is, we burn them.

It is or should be a commodity. That is exactly how transportation fuels work for automobiles, boats, ships and locomotives. Yet, none of these have a single fuel that meets all requirements: cars have octane requirements varying from swill to super. Same with marine gas engines, others use diesel type fuels which have no lead, by the way, and if steam ships still are around, they can use anything that will burn from coal to oil to wood, as long as it gets hot enough to boil water,.

This is the core matter: gasoline is a commodity item used in large quantities with a very mobile fleet. We also have very strict limits on fuel reserves for flight.

The problem I see with the STC issue is that aircraft leave the local airport pattern to actually be useful for transportation, will ultimately end up somewhere, needing fuel and not have the STC for brand X fuel, and although it may work just fine, cannot legally put it in the tanks.

It is purely absurd that an STC exists for every airframe and engine pair and is required. If the fuel is safe, then fine, amend the primary TC or fuel specification to include the fuel being offered. Then it is restored to what it is: a commodity to store energy in liquid form to make a propeller turn and move the airplane.

It is even more absurd that I have to have a fuel STC for brand X, Y, Z, …,

If I wanted to invest in the development of a fuel, and pay for the R&D costs, I could have easily bought stock in the company (if it offered it) and waited for the return after sales commenced. Instead, I’m being told I have to pay for the R&D cost of a commodity which should be making enough money to repay the developer for its R&D costs which have already likely received substantial tax incentives, aside from the fuel initiatives through the “universal” STC.

Can you imagine the nightmare if this same thing happened in 1971 at the local Shellgas pumps? Standard Oil never had it this good.

44

It seems GAMI doesn’t want to go through ASTM testing in fear it will reveal their secret new avgas formula. Surely I am oversimplifying but why not simply patent the formula, go through ASTM testing, then sell the rights to produce the patented formula? GAMI gets their money, G100UL can be made by many producers, and shipping/tanking issues follow industry standards.

45

GAMI’s fuel is patented, however as alluded to above, there are warnings about cleaning up any fuel that makes contact with paint immediately. There are a lot of smart fuel manufacturers who have said the problem is difficult to get something that matches 100LL and all the avgas requirements. There’s likely a reason that they did not pursue fuels with similar contents to G100UL previously.

To all those pushing MOGAS, it isn’t a slam dunk. The shelf life of MOGAS is shorter than AVGAS. That’s one of the numerous requirements to be met here. Vapor lock is another issue.

46

Uh, fact-check: GAMI has detailed inappropriate requirements in the ASTM standard, and gaps. Read GAMI’s web site thoroughly, FAQs for example.

I have the impression Swift also wants changes.

47

I am disgusted with people who think they can fly airplanes but have a conspiracy theorist epistemology.

Yes, many crash, such as the person who departed a runway that did not have lighting, was advised not to but proceeded anyway - to death of he and pax.

48

MOGAS may not be “slam dunk” but Peterson mogas STC’s are based on no/low risk. Can easily be checked with a vapor pressure tester. Vapor lock is not unknown even with 100LL. Shelf life for avgas seems to be 12 months while premium car/mo gas is 9 months which is hardly an order of magnitude better. In Alaska, premium unleaded 92 octan car gas is around $3/gallon while 100LL is $8.00. That’s a compelling difference. !

49

Not all aircraft can run the lower octane Mogas, and try getting non-ethanol mogas in California… and it’s still a major alteration (i.e. STC) to the aircraft.

50

That’s true but but according to EAA, 65% can; that’s a lot. The Petersen STC seems to be under $500 and although it is called a “Major alteration”, it is only a piece of paper.

51

That’s like UL94. And for comparison, an STC for UL94 is not required for many aircraft that were approved on lower octanes.

52

That’s a lot of planes, but it’s not a lot of gas. Those airplanes only consume about 30% of total fuel sales. The few remaining planes that require 100-octane consume about 70% of all 100LL.

53

That is not universally true. Their website (if you read it carefully; they don’t exactly make it obvious at first glance) even says that some alterations may be required. In the case of the PA28s, it requires new fuel pumps if I recall correctly. There are also some other caveats to be aware of too, so it’s not “just a piece of paper”.

54

Further on the ASTM route:

The ASTM standard for ETBE secures that a fuel will have < 1 % of ethanol in the final blend. It is the same maximum ethanol content as is approved for the current 100 LL.

I doubt it is correct that ETBE is banned in California. Can someone verify please? Otherwise would not the PAFI project continue their work on such a fuel and not the world largest producer of ETBE Lyondell be involved in the AVGAS process.

Myself I am living in Sweden on the other side of the Atlantic.

When a fuel is blended such as 100 LL only approved components may be used. Novel components used shall in their turn have an ASTM standard. In that way a consistence is guaranteed. Then a single components could meet the ASTM standard but also exceed the requirements, for example being more pure. Thus not all 100 LL fuels for example are the same.

My back-ground is in the pharmaceutical industry. The path to obtain a safe unleaded AVGAS very much looks like the way new pharmaceuticals are released to the market.

The time line for bringing a new pharmaceutical product onto the market is usually 10-12 years so the time-line I indicated for a novel AVGAS without an existing ASTM standard is not out in the woods.

The individual CBIXBY indicates that I am in a bubble and this is correct . My bubble is green and I personally have the favor in the AVGAS world to design, produce, distribute and fly on it. So the ASTM here has been my help in Sweden. I introduced unleaded AVGAS 80 in the year of 1981 with nationwide distribution. Even the Royal Swedish Airforce used it for their aircraft. This was possible because the ASTM standard D910 at that time contained AVGAS 80 and a foot-note stated that unleaded AVGAS was permissible. When I designed the unleaded AVGAS 91/98 also the ASTM D910 standard helped me – because the standard did only stipulate a maximum amount of lead – no minimum value. The Hjelmco AVGAS 91/96 UL was released in the year of 1991 and approved the same year by the Swedish Civil Aviation Authority. Year 1995 it was recognized by engine manufacturer Lycoming covering a large number of their piston aircraft engines. This fuel is now the dominant AVGAS in Sweden and has about 80% of the total AVGAS annual volume in the entire country. Later on the ASTM here assisted and created standard D7547 where it now resides as UL94 – so UL94 is not a US product of origin. So the fact is that we have continuous production and use of unleaded AVGAS in Sweden thanks to the ASTM for more than 43 years and we have no technical issues.

I developed a high octane unleaded 100 octane AVGAS during the years of 2005-2006. The fuel was tested in Switzerland by the Swiss civil aviation authority and the German DLR (similar to the US NASA). Formal reports in the range of many hundred pages were published primarily on its environmental qualities, exhaust components and particle sizes. The fuel itself is safe for the engine.

But at that time I realized I had to incorporate a new high octane component, ETBE, for which there was no standard and the ASTM helped to bring such a component standard just for a fuel for piston aircraft engines. That standard was approved year 2016. But still there is no standard for a finalized fuel containing ETBE. This work is still going on and the competent people of the FAA in Atlantic City are involved in this project which is called PAFI to verify that novel components used are suitable for the engines and aircraft out on the market.

To summarize: Be glad that we have the ASTM and that industry takes the time and money and works in the favor to bring a safe fuel for your use to the market and which will allow competition among component and fuel producers to have such a fuel available wherever you will fly in the world and at the best available prices.

As a foot-note: yes an ETBE fuel even if reaching 100 octane unleaded may not satisfy all piston aircraft engines out there at a reasonable cost per gallon. For them there is a solution – water methanol injection. Such systems are made in the US and certified and they have a long story of success from the second World War. Cost wise for the GA-market this solution will probably be the most cost-effective. An overall majority may operate on a cost effective fuel at best available price, the other aircraft can use the same fuel but have to make an investment in their air-frame.

55

Lars,
George Braly.
The California regulation states that neither MTBE nor ETBE may be used in any fuel for any “self-propelled motor vehicle.”

Maybe there is some way “around that” - - but it is an “issue” that the many PAFI / EAGLE people have chosen to ignore.

As far as “methanol - water” injection is concerned - - from 1) a certification point of view ; and 2) from a practical airport “logistics / availability” point of view - - the widespread fleet deployment of that “solution” is a complete phantasy.

There would be an impossible number of practical issues to be overcome, such as, airplane make/model specific “re-writes” of the existing FAA Approved Flight Manual Supplements. That along could keep a couple of FAA DERs with flight test and engine-powerplant “authority” busy on a full time basis for a year or more doing nothing but drafting that language and validating that on those individual make/model aircraft.

1 Like
56

You are correct for PA 28-160’s and above but not below where the STC is a piece of paper. Pieces of paper are a necessary evil of life but have more importance to some and less to others. For me, the least complicated way to obey the rules and do the job properly is preferred. Those who feel more comfortable with complications are welcome to take that route. 9000 TT, SMELSES, COMM., A&P/IA, M.Sc. CE, MBA 84 and still flying.

57

That’s interesting ! So the 30% that can live with a simple option will be forced to go complicated to help support those who can’t go simple ? Not my preference for “foreign” aid. I would want the gas sold to the upper 70% carry a surcharge to subsidize the extra cost of my having to buy 100UL instead of Mogas. Thank you for your gift.

58

It’s certainly understandable why there would be confusion on this issue. It’s a matter of defining the terms, and deciding what those terms will show. What’s needed is a Sustainable High energy Interim Transition. So the question is what will a Sustainable High energy Interim Transition Show?

59

For me a vehicle is a vehicle and and aircraft an aircraft. In my country a vehicle can never be a traditional aircraft - but there are flying cars out there so this is perhaps not the final word about ETBE in California?

For me the logistics with water methanol is no big issue. We have a number of aircraft made in the US that rely on anti-icing and de-icing based on fluid de-icing using ethylene glycol or isopropyl alcohol. I have had these components in gallons in my hangar for a PA-30 and de-icing of propellers. Nothing says that not the same logistics can be done with water-methanol. FBO:s should also not have the problem to assist here if you are en-route.
There are STC:s out there on water methanol injection systems for GA-aircraft for example such as Beechcraft Baron.
Petersen Aviation in Minden NE owns such STC:s I think. Such a STC allows 100 octane aircraft engines to operate on even autofuel with low octane. Typically water methanol injection gives you about 12 aviation octane. With an ETBE AVGAS having 100 octane the additional 12 octane will serve basically the entire fleet that needs more than 100 octane.

There could also be other options – GAMI worked long time ago on their PRISM system, with variable ignition timing. My 91/96 UL AVGAS/ UL94 (which is not an ETBE fuel) was tested by GAMI some 20+ years ago and with their PRISM system on a Lycoming TIO540-A engine. With everything on red in their test-cell the engine did not detonate. It was all observed by among staff from the AOPA and the AOPA-Pilot had an article about it.

I would not be surprised if others engineers with piston aircraft engine manufacturers in the US have worked on this issue. Look at the Lycoming iE2 which states it will work on UL100.

ETBE fuels could also get more than 100 octane but then an efficient scavenger is needed for the additional amount of MMT. MMT is a metal that here works as an octane enhancer. Such efficient scavengers exist outside the US.

In Europe it seems to be we will be allowed to use 100 LL until 2032 so there are another 7-8 years available to refine fuel formulas.

Lead is still the cheapest way to obtain octane numbers - which is appreciated by the GA community.

60

“For me a vehicle is a vehicle and and aircraft an aircraft. In my country a vehicle can never be a traditional aircraft - but there are flying cars out there so this is perhaps not the final word about ETBE in California?”

Lars, maybe that is your definition of a vehicle.

But Merriam-Webster would disagree:

Definition “vehicle”

  1. a means of carrying or transporting something.
    | planes, trains, and other vehicles.

That makes it pretty clear. Do you agree ?

         *********

To adopt Russ Niles paradigm for this editorial, I am just a small town kid who grew up nearby on a ranch. I only have about 56 years of flying experience. And I have only been doing FAA Certification for just 29 years.

I designed and operate one of the worlds most technologically sophisticated aircraft engine test facilities, but everyone should ignore that.

So I may not have a full understanding and appreciation as to just how simple it would be to make my high compression (8.7:1) turbocharged engine operate on 80-90 octane mogas - - using water-methanol injection.

But there would have to be enough of that water-methanol fluid on board the aircraft to operate continuously for 4.5 to 5 hours to support my Bonanza, because it cruises at 75% + power, and would detonate to destruction on mogas (without the methanal-water injection) in about 60-90 seconds.

Then, I am not sure what kind of storage tank there would have to be, nor where it might be located in that airframe. Rumors are that the methanol is pretty hard on a lot of traditional fuel wetted materials.

                    ***********

Dropping the “humor” - -
What Lars is proposing is not a realistic solution and the physical alteration to the engines and airframes to implement that “solution” would rival the cost of an engine overhaul to modify each aircraft.

My $0.02 for the day.

1 Like