Unleaded Avgas: All On The Same Page (Not)

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There’s all kinds of shaking going on in the unleaded avgas sphere, as evidenced by revelations at Oshkosh this year. Those of us who expect the progress of science and commerce to be orderly and stately might be dismayed by the apparent confusion, indeterminacy, contradiction and flawed human behavior in the quest for a lead-free world.

Students of the history of both discovery and enterprise will see the repeat of that history, with all its wart-bespeckled lows and heady triumphs. All this to facilitate a future 50-gallon avgas fill-up.

There are four players now pursuing unleaded avgas certification: Shell and Swift, who had been selected by and participating in the now-stalled PAFI (Piston Aviation Fuels Initiative); GAMI, who has been working in this space for almost two decades; and a Phillips Petroleum/Afton Chemical consortium that announced at Oshkosh their intent to follow the GAMI path to an STC'd fuel. 

The FAA in May announced that they had encountered issues requiring mitigations for both the Shell and Swift fuels, implying that neither fuel could meet the needs of the fleet. Lacking a plan to address these mitigations, and being short of funding to complete lab and flight testing that was as much as half done, the FAA suspended further testing. It also slipped the completion date a year to 2019 and said it needed more money.

The FAA's interpretation of its legal authority is that it cannot approve a fuel as a fleet-wide replacement without special authority from Congress. Not all observers agree with that characterization, but it is conservative. Participants in the unleaded certification effort point with pride to the specific language in the FAA reauthorization legislation that confers such authority upon the FAA.

However, the reauthorization bill has only passed one chamber thus far and the president hasn't signed it. So that technical detail remains along with question: Can we do this at all? Perhaps we will be well served by the STC applicants after all. History lesson: Phillips' XC 20w50 oil was originally approved on an STC, because there was no relevant milspec for multi-viscosity at the time it appeared. So there is precedent.

One issue that PAFI participants have shared off the record is that non-linearities have been observed in comingling the two fuels with each other, and with 100LL, in various ratios. It's surprising that this surprises the FAA; gasoline blending is inherently non-linear. The ASTM's multi-industry Coordinating Research Council (CRC) that had been researching unleaded avgas alternatives since 1991 made a number of observations of these characteristics.

Certainly it's an issue. Although CRC never delivered final recommended fuels, they did make scientifically valid suggestions on how these comingling issues could be addressed. It seems the FAA folks weren't paying attention, or have forgotten what they'd heard.

Those affected by PAFI's decision to pause fall into at least two schools. Those with a background in government contracting point out that given the competitive nature of the fuel selection, the FAA would put the entire process at legal risk if they change the rules as they go along to address this current concern. Thus the pause, in their view, is essential to protect the integrity of the program from legal challenge. Those who were eliminated in earlier rounds could legitimately complain they were unfairly treated if certain contestants were given another bite of the apple without extending the same opportunity to others.

The fuel proponents, however, are less concerned about the FAA's potential legal troubles; they feel they're being placed at a competitive and cost disadvantage by delaying the testing. Once begun, the testing should be completed as outlined, they feel, to be fair to the two contenders chosen by the process. Otherwise, they're being burdened with a cost of delay that they didn't sign up for at the beginning. The particulars that emerged at AirVenture this year show how chaotic the PAFI process has been, at least from the outside looking in.

Shell gave two sessions by Tim Shea, director of Aviation R&D, on Monday and Wednesday. The presentations were oddly different. The first session, co-presented with Continental's Tim Kenney, was largely glad-handing, with the message being that Shell is good, unleaded avgas will be awesome. See you next year. Audience members asked Shea to comment on the PAFI pause. Shea deflected, inviting Oshkosh attendees to ask the FAA at the FAA's PAFI presentation. When the audience explained that the FAA had not scheduled a PAFI presentation, Shea seemed genuinely stunned, noting that he had expected the FAA to be presenting.

The second session, two days later, with Lycoming's Michael Kraft, was more in depth and did address PAFI's pause. Spirited disagreement exists between Lycoming, which believes the pause is essential due to federal regulations and essential to eventual success, and Shell, which wants the program to continue apace even with the problems identified.

Shea seemed to let slip that Shell's formulation relies on heavy alcohols instead of an -OH group with 1, 2 or 3 carbons, substituting perhaps a handful of carbons, thus making a less hygroscopic/water-loving additive. That would be more suitable for inclusion in avgas. Kraft verbally chided Shea for nominally violating the PAFI non-disclosure agreement in discussing this formulation detail, but his objection focused the attention of all attendees on the apparent gaffe.

Shell's Shea cast shade at GAMI without naming them. Shea claimed the GAMI STC process is less open and transparent than the PAFI process, implying that this was unfair to the industry. But observers noted that the PAFI process has been inscrutable to outsiders. Perhaps PAFI does a better job of sharing with participants within industry, but not with the aviation press, or with pilots and aircraft owners—the actual customers for the fuel.

Shea waxed slightly dramatic, opining that no one knows what's in the proposed STC'd fuels, what tests the FAA might or might not make the STC applicants perform, and whether or not a specification for the fuel would eventually exist. But the same is true regarding formulation and testing for the PAFI fuels, including Shell's. When the process completes, it will be apparent whether a specification exists or not. Of course, if anyone plans to actually sell any of their fuel, a specification will be essential.

Shea also took an odd tack on the driving force for the entire unleaded avgas effort, implying that since the EPA has abandoned a lead endangerment finding, a decision made shortly after the Trump administration began exerting sway at the EPA, why should industry do anything at all? The majors are perfectly happy selling a high-margin fuel that is protected by competition from upstarts by the large environmental liability of lead blending.

The conceit is that the majors already bear the lead blending burden, since using TEL in mogas began in the 1930s. But any new entrant would be inhibited from entry into avgas blending by incurring that liability. These aren't the sort of musings that corporate public relations departments like to hear their managers articulating in public. Shea seemed to ignore the lawsuits by environmental group seeking to force the EPA's hand on a lead ban. FOE (Friends of the Earth) and NRDC (National Resources Defense Council) have current focuses on the lead issue, and others could take up the banner.

And of course, administrations do change, and even a given administration can rethink its policy issues. So even if the EPA doesn't issue a lead endangerment finding in the next year or two, it's far from a dead issue. And don't forget, if the sole remaining western lead plant, Octel's near Liverpool England, burns down tonight (bad news for the downwind neighbors), it seems unlikely that anyone will be rushing in to reinvest in this end-of-life-cycle technology.

Moreover, an unleaded solution will be good to have. Lycoming's Kraft pointed out that unleaded fuel will offer many other benefits to aircraft operators: longer oil change intervals, availability of superior lubricants currently eschewed due to their inability to solubilize lead salts, and advanced engine control systems relying on lambda sensors that would today be slowly destroyed by lead salts in the tailpipe. 

Phillips Petroleum and Afton Chemical introduced their MMT (methyl manganese) formulation. They forecast it will be certified via STC by 2022. The speakers started out being cagey about the formulation of their fuel, "similar to existing avgas." The caginess was odd, since Phillips' pre-printed handout said that the fuel was identical to current avgas, except using MMT instead of lead as the octane enhancer.

The Phillips speaker finally conceded what the handout declared. Audience members asked about MMT spark plug deposits. EPA has reported that General Motors found that plugs could become contaminated in as few as 16,000 miles.

These concerns are "not valid," Afton's representative claimed, but he advised that Afton was reformulating the manganese scavenger anyway, to solve this non-problem. That's an odd business decision, in my view. Canadians will have to inform us on the spark plug glazing issues much touted in the technical press when MMT was used in mogas up north. This made their sparkplugs throwaway items, not readily cleanable.

When asked about this, the Afton representative replied that he spoke with authority, because he is a Canadian. But perhaps the unneeded and unnecessary manganese scavenger reformulation will address this issue. 2022 is a long way away, and of course that's a date from the heady early days of this effort. Still, it’s good to have an avgas heavyweight like Conoco-Phillips adding its weight to the fray. But a lot remains to be demonstrated in the engine durability testing required for certification of their proposed formulation, STC or not.

GAMI did not present at AirVenture, but the company is continuing toward STC approval certification. GAMI hasn’t revealed the exact formulation, but has confirmed that it’s based on aviation alkylate with an aromatic hydrocarbon additive package for octane enhancement. GAMI has been assembling all the pieces and seeking FAA approval for every step of their science, supply chain, blending and distribution, including launch customers to gather data to support an ASTM specification application. The FAA has implored GAMI to enter the PAFI process and GAMI has firmly demurred.

Assuming GAMI is permitted to complete their project within the scope of their FAA-approved certification plan, there could be many airplanes operated daily on GAMI 100UL by this time next year by a couple of launch customers, with broader approvals and distribution in the next two years. It may then live or die in the market, depending on its merits. 

Swift’s CEO Chris D’Acosta held forth on Swift 94 and 100, declining to discuss PAFI results. While Shea dissed GAMI, D’Acosta went after Phillips/Afton by passing around vials of a purported alkylate manganese mix that looked like sewage samples. Oddly, this criticism came shortly after he made a remark about not denigrating his competitors.

D’Acosta exhorted the crowd, "Would you put this stuff in your airplane?" Of course, we couldn't analyze Swift's fuel samples to see how they were compounded, so no technical detail is forthcoming. The refining industry did blend with MMT for years without flocculation—fine particles in the solution clumping together—being a serious concern, so this strikes me as more obfuscation than technical critique.

Both Shell and Swift might be better served by observing D'Acosta's words and favoring their audiences with details about their own products rather than casting doubt on the other guys'. Taken together and considering PAFI’s unimpressive results thus far, the road to unleaded avgas looks bumpier than ever.


Paul Millner is a retired refinery executive with expertise in avgas production. He edits the Cardinal Flyers Online newsletter.

Comments (33)

It seems there is an unintended gaffe in the spelling of "apparent gaff" :-)

Posted by: A Richie | August 15, 2018 9:25 AM    Report this comment

"Would you put this stuff in your airplane?"

This is profound.
Regardless of which fuel is selected, on that first takeoff, what will YOU be thinking?

Posted by: A Richie | August 15, 2018 9:31 AM    Report this comment

Excellent, informative article. Thank you.

Posted by: Gary Risley | August 15, 2018 10:43 AM    Report this comment

"Regardless of which fuel is selected, on that first takeoff, what will YOU be thinking?"

I'll be thinking "I'm glad I'm not flying behind a high-HP engine that needs 100-octane fuel" ;-)

Joking aside, I've been saying that I'll be glad to do away with TEL because I won't have to worry about lead fouling as much. But I hadn't considered until this article mentioned MMT that plug fouling or corrosion or whatever could potentially still be an issue. It makes me wonder if the aviation community might be better served by having a 94-octane fuel (or whatever octane the aviation base fuel is) and a separate high-octane fuel for those planes that require it.

Posted by: Gary Baluha | August 15, 2018 11:13 AM    Report this comment

Once again the FAA is here to help us. Government getting involved always stretches the time line and causes the costs to increase exponentially. For some reason, I have a deep feeling that the PAFI will go the way of all other 100LL replacement programs. It will just fade into the sunset of other abandoned programs.

The best hope is the private industry will develop an acceptable replacement. Of course, private industry will be fighting the full weight, strength and financing of the FAA. An unleaded fuel will be a great boon to increased engine life for our old LyCosauraus engines.

Posted by: Leo LeBoeuf | August 15, 2018 12:32 PM    Report this comment

"Taken together and considering PAFI's unimpressive results thus far, the road to unleaded avgas looks bumpier than ever."
Yeah. In engineering-speak, "the road" is a complete cluster-f*ck.

With apologies to the Rolling Stones, you can't always get what you want. From where I sit, the "program" has REGRESSED to the "let's (re-)define what we actually want" phase.
Now we all can circle back to the recent discussion about diesels. Lather; rinse; repeat.

Posted by: YARS (Tom Yarsley) | August 15, 2018 1:06 PM    Report this comment

My personal fondness for GAMI certainly wants me to see them succeed. It's admirable how many times they've been willing to butt heads with the FAA for the good of general aviation, despite how many times their efforts have been stymied. Imagine where we'd be in a world without lean-of-peak flying. How much more lead would we be burning then?

That aside, I'm still yet to see a good answer on why ETBE isn't a suitable octane enhancer for Avgas. MMT has too many component lifetime problems, I agree there, and MTBE's toxicity and ability to render aquifers undrinkable is unacceptable. But ETBE seems like it would fit the bill. More expensive than lead, sure, but so's mesitylene, and I'd give someone a friendly even-money wager that that's what's in GAMI's fuel.

What gives?

Posted by: Joshua Levinson | August 15, 2018 1:13 PM    Report this comment

I have been using auto gas for years with excellent results. I am not a chemist or an engineer. My understanding comes from the thorough testing that was done for both the EAA and Peterson mogas STC plus 20+ years of practical, common sense usage.

So far, my plugs last longer, oil stays cleaner, valves run cooler, and no degradation of internal engine parts. I have tested each purchase of fuel for ethenol contamination and never have detected it any purchase I have made. So, why all the mystery, setbacks, and chemical gasoline-speak such as " non-linearities have been observed in comingling the two fuels with each other, and with 100LL, in various ratios"? 80+% of the GA fleet would run fine on presently available non-ethanol mogas. Engineering for the remaining 20% cannot be such a mystery.

My low compression, 200HP, 4bll carb, 259 ci V8 63 Sudebaker Lark runs on the same fuel as my high compression, 340hp FI 5.7 Hemi in my 2008 Chrysler 300C, and the same fuel powers my Continental 225-8 in the Bo.

Politics always trumps practicality, bypasses the consumer, and is devoid of any common sense.

Posted by: Jim Holdeman | August 15, 2018 1:44 PM    Report this comment


It's not the engineering that's the mystery, it's the economics. That remaining 20% (or 30% is the number I usually see) burns 70% of the volume of fuel. There are still plenty of cargo, charter, bush, ag, and whatever-else-have-you flying high-compression piston twins and some of the larger singles. If you "engineer" them a different (read: much more expensive) solution, they're gonna migrate to turbines burning Jet A.

Avgas, with cheap lead, is already a marginal business. The oil companies are not going to produce a more expensive, niche product, for 30% of the current volume. It's just not gonna happen.

If we don't have a solution for that 20% (or 30%) of the fleet that also works for the low-compression folks, then avgas will simply vanish. That's the economic truth. Clean 100 octane is the only solution that will work. Red Avgas ain't coming back, a single, drop-in, fuel is the only viable choice for the piston GA fleet.

Posted by: Joshua Levinson | August 15, 2018 2:17 PM    Report this comment

"A single, drop-in, fuel is the only viable choice for the piston GA fleet." Indeed.
But I have to quarrel with the word "choice," as it implies existence/availability - which, after all this time - still is a (exhaust) pipe dream. I'd substitute "objective."
This latest round of obfuscation is a vivid example of goalpost-moving, a.k.a. characterizing every defeat as a victory.

In a larger context, there are forces - still afoot - whose objective is clear and unchanged: "get the lead out." Those forces really couldn't care less how GA achieves THEIR objective. But - again, high-level - it appears that GA's available strategies are;
1. Change aircraft.
2. Change engines.
3. Change the fuel that our aircraft engines burn.

For the most part,
Strategy 1 is possible - if unafordable for many/most.
Strategy 2 is available only in limited circumstances (STCs, etc.).
Strategy 3 is... at the moment, a pipe dream.
See you at the strategy meeting.

Posted by: YARS (Tom Yarsley) | August 15, 2018 3:51 PM    Report this comment

The PAFI project is a classic example of letting government lawyers set up the process rather than using chemists and engineers. This should have been a collaborative effort to achieve the end goal, rather than a competition to see who wins. Unfortunately, government can't seem to know the difference, so they end up with the predictable (non) results. Maybe they should send both Shell and Swift back to the lab, dissolve the PAFI program and tell everyone that the STC process is open to all comers. Let science and economics determine the eventual winner(s). Right now, GA is the collective loser.

Posted by: John McNamee | August 15, 2018 5:06 PM    Report this comment

It sounds to me as if the existing avgas specification is faulty (and it is). It should be robust enough that anyone meeting that spec with a lead free product could just go to market with their new fuel. Of course, the spec needs to include mixing with existing fuels and materials at any ratio, but hey, write a PROPER specification, and let the chemists have at it!

Posted by: Ripley Quinby | August 15, 2018 5:55 PM    Report this comment

Why are we debating or fretting over this PAFI thing, gentlemen? Didn't ya'll get the memo? The future is electric flight. More specifically, multi-rotor autonomous people movers where pilots are no longer needed or even optional. I even heard that some sort of system to turn a C172 into an autonomous vehicle has been designed as an interim step. I saw a nifty looking contraption in the Innovation area of Oshkosh ... I think they called it a 'Black Fly?' Erik LIndberg has started a Company to manufacture urban autonomous flying taxicabs. Why even Airbus thinks electric airliners are on the horizon. I'm not so sure how they're gonna make hypersonic electric airplanes but I'm sure some genius somewhere will figure it out. I just hope we don't run out of electrons next ... or discover that breathing spent electrons is hazardous to your health.

It's a brave new world out there in the NAS don't ya know? And with ADS-B now almost complete in just 16 months ... all those buzzing electric machines won't even clunk into each other. Pseudo radar will alleviate that possibility.

Posted by: Larry Stencel | August 15, 2018 11:59 PM    Report this comment

This whole premise is WRONG.
There is zero scientific evidence that the small amount of lead in the minuscule amount of AvGas being used is actually causing any problems. None.

It's time to speak the truth and be reasonable.
AvGas is here and is not a pressing problem that needs to be addressed.
The only thing the FAA might need to do is address a need for a 2nd source of lead in the interests of preventing a crisis in GA if the primary source is disrupted.

Posted by: Mark Fraser | August 16, 2018 7:40 AM    Report this comment

"There is zero scientific evidence that the small amount of lead in the minuscule amount of AvGas being used is actually causing any problems."

I presume you mean from a human health perspective. The two real problems are: what happens if the current sole provider of TEL goes away, and getting the lead out has the potential to save money in the long run from fewer fouled spark plugs (presuming the TEL replacement doesn't cause its own set of issues). The first problem is the main reason I'm for a lead-free fuel, though.

Posted by: Gary Baluha | August 16, 2018 8:28 AM    Report this comment

I'm surprised. Nobody here has yet connected the dots and addressed the "real" fuel problem directly.

Out in my garage, I have a vehicle which says, "FlexFuel" on it and has a yellow gas cap. It'll run on Mogas or E85. Neither fuel has lead in it. Some magic box under the hood collects information about the engine and makes adjustments for either fuel. Why ... WHY ... don't airplanes do that. It's 2018 for gosh sake! The world will end via a horrible carcinogenic apocalypse soon after young kids start growing two heads if we don't take the minute amount of lead out of aviation fuel. There's little time left to save mankind.

We're flying around behind tractor engines! Why? We all know why. For years, there's been a couple of companies working on electronic ignitions in booths at Airventure but aside from E-AB and LSA airplanes and a few exceptions, you don't see the devices on great numbers of certificated airplanes. We're using tractor carburetors and magneto ignitions with fixed timing (except for the impulse coupling) because a certain know-it-all group of people running the FAA are hell bent to control everything. OH ... and don't forget the trial lawyers who are saving us from all manner of dangers in life, too ... thanks very much, guys.

We could probably run our airplanes on dishwater laced with a few hydrocarbons if only the FAA would wake up and enter the 21st century ... (sound of Larry 'sighing' in background). We could call it PBF ... Performance Based Fuel.

Posted by: Larry Stencel | August 16, 2018 9:54 AM    Report this comment

The FAA needs to do the reasonable thing and promote a 2nd source of TEL or do the next reasonable thing and promote methanol free MoGas.

It's not reasonable to re-engineer 100 years of aviation because of a misperceived and overreaction to a non-threat.

Posted by: Mark Fraser | August 16, 2018 10:18 AM    Report this comment

Larry, have you've forgotten about Continental's PowerLink? Been out there for almost 20 years. Odd thing is, nobody wanted to buy it. Next up is the Lycoming IE2, to be certified on the Tecnam 2012 Traveler. But still needs 100-octane fuel; the ignition can't bridge the octane gap.

Posted by: Paul Bertorelli | August 16, 2018 10:20 AM    Report this comment

All those electric airplanes will be spewing ozone into the upper atmosphere causing all major cities to be under water. No matter what propulsion system is used, someone will complain.

Now if we can get the FAA off their duffs and work with manufacturers attempting to develop FADEC systems for our existing engines, life would be much better. Fat chance.

Posted by: Leo LeBoeuf | August 16, 2018 10:34 AM    Report this comment

Guys (and gals):
Whether TEL is an environmental threat is immaterial.
The REAL problem is that vested interests have laid claim to the environmental-apocalypse moral-high-ground - and some of them wear black robes and swing wood gavels. And - right or wrong - one gavel-smash could bring much of light GA to a screeching halt.

In light of recent developments, finding the Holy Grail may be easier than finding some lead-free magic compound that retards the speed of combustion.

Posted by: YARS (Tom Yarsley) | August 16, 2018 10:50 AM    Report this comment

Paul ... Mike Busch has an excellent webinar entitled, "What's Changed, What Hasn't" which bemoans the very same issue of "Fred Flintstone" airplane engines. I'm well aware that there are a few exceptions but ... that's what they are ... exceptions. Unless and until a modern day engine gets put into a modern day airframe that weighs more than 600kg, nothing is gonna change. The Feds are a major impediment on that front, too.

I know it can be done ... the Rotax 912iS cum 915iS is one that immediately comes to mind. A few years back, I talked to Dick VanGrunsven about why he was still using the 912ULS in the RV-12. H e said, "that's the way I designed the front cowl and that's that." A few years later, he saw the "light." I'da likely bought the RV-12 I flew at Sebring (first one with the G1000 suite) IF it had the iS engine but ... too late now. I could see the RV-9 with a nice mogas burning 915is -- or equivalent -- as an example of a fine airplane for most people.

Non ethanol mogas would work NOW for most engines with some tweaking.

There are SO many effronts to 'certificated' GA that I don't hold out much long term hope for it. This fuel "initiative" is still another razor blade cut in the process.

Posted by: Larry Stencel | August 16, 2018 11:28 AM    Report this comment

A couple of years ago, I said in this space: "my next airplane will burn kerosene." Unfortunately ( ? ), it looks like I was right.

Posted by: YARS (Tom Yarsley) | August 16, 2018 11:37 AM    Report this comment

"Non ethanol mogas would work NOW for most engines with some tweaking."

I agree with Larry. We have a replacement. We have had it for years. We have the technology today to make all existing engines, old and new, to reliably run on ethanol free mogas. Technology is not the issue.Chemistry is not the issue. Politics, bureaucracy with the intersection of the two called the FAA is the stumbling block.

With the current certification, testing, and validation stumbling blocks, the bane of all GA technology, there is no economic way for EFI, FADEC controls, ignition/timing advances to get into the GA aviation marketplace. And if they did, there would still be the remaining GA "giant " companies who are considered "too big to fail" that would provide all the remaining resistance necessary to prevent change.

Actually, the promised demise of avgas with no so-called drop in replacement should be to my personal advantage, and to the 80-85% of the aircraft owners who can use ethanol free mogas today. When avgas ceases to be produced, and after all the hand wringing over economics vs chemistry vs PAFI vs pollution vs whatever is next in line to be versus with...my 53 Bonanza's value should go up as fast as the overnight depreciation of an IO-550 powered SR-22. Along with the remaining 80-85% of the fleet that can use $2.50 a gallon fuel today. Makes my 64 year old, pressure carbed, electric prop equipped 150kt hot rod a potentially good investment.

Imagine that, Garmin would have to think about certifying a G1000 for a 53 Bonanza. And Chinese owned Continental would have consider bring back the E series engines....Maybe I need to find some real estate near Kingman, AZ and start collecting airplanes representing 80-85% of the existing GA fleet. At least there is a future in that.

Posted by: Jim Holdeman | August 16, 2018 1:48 PM    Report this comment

"We have the technology today to make all existing engines, old and new, to reliably run on ethanol free mogas."

It's not a technical issue, it's a cost issue. Many pilots are complaining about sinking $1500 into ADS-B Out, so I doubt they'd be willing to sink even larger sums of money into adding electronic controls to their engines to run on unleaded avgas. And there's the possibility that those controls would effectively derate the engine, so book numbers will be even less useful in preflight planning.

I would think if there was an easy and airplane-affordable way to modify an engine to run on ethanol-free mogas (which is somewhat difficult to find here in the northeast, last I checked), such a product would likely already be available.

Posted by: Gary Baluha | August 16, 2018 2:51 PM    Report this comment

EFI and FADEC never sold on the certified market because the costs were insane. It's nothing inherent to the technology--automotive-derived EFI is available for Lycomings on the experimental market for about $6k, which isn't bad at all when you sell off those mags and your existing carb/ijection system--but merely the fact that the FAA would require any such system to meet requirements that magnetos and carb/mechanical injection could never hope to meet. And then all of that has to be produced under rigid FAA control of everything down to farts on the production line. Put EFI on your formerly-carbed engine and you'd probably make back the remainder in fuel savings over a year or three.

The only "derating" you'll get from adding electronic engine controls is what you'd have to add if you want to run lower octane fuel in a high compression engine. Otherwise, more even fuel distribution and variable timing give you lower fuel burn under most conditions, a smoother engine (especially at idle), and operational simplicity, for no loss of power at all.

This is all just another reason I'm glad I'm on the homebuilt side. Come on in, the water's fine... and we have cookies!

Posted by: Robert Gatlin-Martin | August 17, 2018 5:28 AM    Report this comment

"This is all just another reason I'm glad I'm on the homebuilt side. Come on in, the water's fine... and we have cookies!"

I wish I could. I don't have enough time or money (or build space). What we need is a PNC category, but I guess good luck with that ever happening...

Posted by: Gary Baluha | August 17, 2018 7:36 AM    Report this comment

Gary B ... NOW you've pushed my 'button.' This is MY number one heartburn with the FAR Part 23 rewrite that the FAA is prancing around slapping itself on the back over. What they've done is a joke! What they coulda done would have been SO much better ...

For those that don't know ... the PNC (Primary Non Commercial) idea was substantially covered in the Aviation Rulemaking Committee final report to the FAA Small Aircraft Directorate (at the time, former EAA'er Earl Lawrence) ... after more than five years of working on it. Largely copying the Canadian model as a working example, they proposed that Class I airplanes flown only recreationally could be relicensed into a new category of airworthiness called "P-NC." Essentially, an owner would be turning his/her certificated airplane into a pseudo E-AB. AND ... it was proposed to be a two-way street ... you could go back if you needed to with a survey by an A&P to ensure the machine met its Type Certificate. The ARC even went to far as to include a rewrite of the applicable FARs ... all the FAA had to do is do a NPRM and replace them. They wouldn't have had to do anything but implement it It never happened! Instead, the silly "Performance Based" idea popped up. And we're still saddled with using STC's, AML's and other workarounds instead of installing equipment the way E-AB and LSA with special airworthiness certificates do.

At Airventure, I mentioned this to a vendor with a great product in the Innovation Showcase. I pushed HIS button and we both jumped up and down bemoaning what the FAA did (or didn't).

With respect to the subject du jour -- PAFI -- imagine the great products that small capable companies could come up with to modify existing engines to run on my dishwater idea if only they were unchained from the ridiculous rules that come out of Independence Ave.

I, too, am too old to start building an airplane. I want to spend my remaining aviating years flying, not pulling or pounding rivets. But ... who knows ... maybe someone will come up with the magic combo of engine and airframe that makes my blood boil ... I DO have the room in my hangar now ...

Posted by: Larry Stencel | August 17, 2018 8:09 AM    Report this comment

I agree with the comments about going to modern fuel, spark and timing systems to allow existing engines to run lower octane fuels. Just look at the gobs of power converted fro0m a gallon of gasoline by modern car engines. My lowly 2.4 l Subaru puts out as much horse power as my previous 4.6 l F150. Granted the Subie does not have the low end torque but it converts the gasoline very efficiently into power. The folks on the experimental side are doing great things to increase efficiency and reliability from their engines. Unfortunately, our LyCosaurus certified engines are locked into the 1930s. Good thing that the FAA is not controlling the automotive world. We would still have flat head V8s with 3 speed manual transmissions.

We have met the enemy and it is the gummy mint.

Posted by: Leo LeBoeuf | August 17, 2018 8:45 AM    Report this comment

Something to remember:
Your Subaru engine spends most of its life producing 10% of its rated peak horsepower. Airplane engines spend most of their lives producing 65% - 70%, and a significant amount of time at 100%.
Different world.

Posted by: YARS (Tom Yarsley) | August 17, 2018 9:08 AM    Report this comment

"Your Subaru engine spends most of its life producing 10% of its rated peak horsepower. Airplane engines spend most of their lives producing 65% - 70%, and a significant amount of time at 100%."

I can buy a Holley EFI system that replaces a 2 or 4 barrel carb, which is self-learning, completely self-contained unit requiring only a hole drilled into the exhaust system for the O2 sensor for $995.00. It will support 350-600HP. I don't have to do anything to it but drive. It also gives me the capability to manually tune according to all my drive-line parameters including optimal fuel burn at every shift point, if I choose.. In the high performance environment, these engines only see 100% power.

In the local circle track crowd, cast iron V8s run 4-5 seasons enduring 50-250 mile races weekly without breakdowns or rebuilds at 8,000-8,500 rpm well past 100% power using this technology, with good over the counter available parts that have a 50 years history of usage with and without modern fuel and timing delivery technology. We are not talking NASCAR here, we are talking practical garage based racing that takes place at hundreds of tracks all over the USA every Friday night. And do this on locally available pump gas with or without ethanol.

For the price of a new TSIO-540, I can buy an 707hp Chrysler Hellcat Challenger, flog it at the track every weekend unmercilessly, drive it in stop and go traffic in 100+ degree heat to work, and get a 5 year/60,000 mile warranty to boot on 91 octane fuel if I am racing or 87 octane if I am not.

So, technology is not the issue even for our, old, inefficient flat four/six cylinder airplane engines with restrictive intake and exhaust systems and pathetically lousy cam profiles. Neither is the gasoline the problem. The gasoline already exists and the technology is here today as well, to lower fuel consumption, eliminate detonation issues, provide easier starting, and have the capability to have optimum fuel mixtures for every altitude.

Our aviation bureaucracy prevents amortizing the development costs which can be overcome if certification issues were streamlined as well explained in previous posts.

Having formerly owned an experimental airplane, i agree, jump into the pool, the water is fine. Technological power-plant refinement will not come from Lycoming, Continental , or Wichita. It will only come from free thinking folks in a market driven environment. Oshkosh proves that time and time again. Until then, I better check V-Ref...I think my mogas burning Bonanza just appreciated a tick this morning.

Posted by: Jim Holdeman | August 17, 2018 11:22 AM    Report this comment

Yars, I realize that the Subie only loafs along at low power most of the time. The point that I am making is that our high load aircraft engines will benefit tremendously from similar fuel, spark and timing technological advances. Instead, we are using 1930s tractor technology on engines costing north of $60K.

My 14 hp Briggs engine on my lawn tractor/ snow blower only operates at 100%. It has done so for the last 1500 hours (yes it has a Hobbs) over 30+ years. Still doesn't burn oil either. This is a 30 year old technology. Why does an IO550 only get

Posted by: Leo LeBoeuf | August 17, 2018 12:20 PM    Report this comment

The "auto engines can't make full power output" meme isn't what actually kills auto conversions. Go look at the testing most automotive engines go through. Strength- and power-wise, they hold up.

What fails on them are the installation practices and ancillary systems.

Decades ago, NACA and Piper and Cessna and all the others figured out the basic formula for "here's how you install an air-cooled opposed or radial engine in an airplane". Pretty much every traditional engine installation since then has been basically a tweaked copy of that work.

No such standard practice exists for auto conversions. A few brave souls have tried to make complete bolt-on FWF packages for Subarus, etc. but by and large each installation of liquid-cooled auto engines is a unique installation done to the builder's own ideas, but without a full, proper engineering analysis. Many auto conversions have failed due to torsional resonance, poor gearbox design, improper use of OEM ECUs, etc. And then add on the problems of trying to install a liquid-cooled engine onto an airframe designed for an air-cooled engine--where do you mount the radiators, how do you get coolant to them, etc.?

Some people--generally extremely knowledgeable "gearheads"--have managed to build very reliable conversions. Unfortunately, it remains almost impossible to get the information to duplicate those installations.

There are a few auto engines that would make great conversion platforms for light airplanes. They would be very successful if AND ONLY IF someone with enough resources could sit down and do the full, proper engineering analysis and design, and then produce either complete FWF packages for popular aircraft or provide comprehensive, simple "tab-A into slot-B" instructions and new parts shopping lists that the average person can follow, and which do not include the works "junkyard", "scrounge", or "cannibalize". The problem is, by the time you would have done this, you'd most likely have to charge (experimental) Lyclone prices to make up your development costs and turn a profit, which would turn off a lot of potential buyers. And you could forget about a certified airplane--the FAA would require you to set up a completely separate production line for the airplane engine, with massive paperwork requirements, and that would kill any economy of production.

Posted by: Robert Gatlin-Martin | August 17, 2018 12:25 PM    Report this comment

I don't know anything about effects of the lead put into the air by the GA fleet burning leaded fuel in terms of effects to the human population. However, I do know that we've yet to find a level of lead so low that it doesn't eventually cause neuronal damage in animal models. Lead accumulates in the body and apparently that's the issue. So, while the EPA hasn't stepped in to shut off TEL use in avgas formulation (yet) due to environmental concerns, it's probably a good idea to minimize your individual exposure.

Posted by: Jeffrey Boatright | August 31, 2018 9:09 AM    Report this comment

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