Such a change would also affect the current push by oil companies (presently experiencing record-high windfalls) to drill in sensitive areas.
But this subject is getting far too political for a forum such as TIC170A. If we let politics gain a foothold here at this forum we stand to alienate friendships and lose focus on our beloved Cessna 170's.
As for the topic at hand, and the recently posted EAA website reprint of articles about autogas:
My personal bias is towards exclusive use of aviation fuels for airplanes (big surprise, huh?)
So with that in mind, allow me to point to some glaring (?) inconsistencies in the article.EAA reprint of LPM article: The promised benefits from using
autogas are increased economy in terms
of the price of the fuel and a reduction
of wear of certain engine and airframe
parts such as spark plugs and exhaust
system components.
Lead is also used to provide lubrication
of upper cylinder components such as
valves, pistons, cylinder walls and
valve guides.
Observation: If autogas/mogas is unleaded, yet lead is used to provide necessary lubrication, ...then how is the use of mogas going to provide a "reduction of wear" of engine components, etc.? Another way valve guides get lead is from contaminated engine oil. The result of that is stuck valves. The same thing holds for stuck piston rings. Lead deposits from avgas and lead in contaminated engine oil seizes rings in their piston lands. I don't understand why EAA persists in claiming that lead is good for valves, valve guides and rings. Adding avgas to mogas only contributes the one bad component of avgas to complete the list of harmful fuel components run through your engine.
The economic returns from lower mogas price is the real attraction to this fuel in the lower 48. Availabilty is an added attraction in remote regions such as AK. But the EAA statement is contradicted with regards to their "reduced wear" comments because the mogas has no lead "to provide lubrication"....if you can believe that statement.
For instance, the EAA reprint's later statement: "... upper
cylinder wear problems were the result
of the use of unleaded autogas..." is at least in part an admission by them that mogas caused increased wear (at least in older engines.) I suspect the real reason was not lack of lead, but instead use of non-compatible mogas additives.
There is a common seque made by owners with regard to the changes made in aircraft engines in the late '70's/early 80's. It is commonly believed that changes were made in valve/valve seat design in order to facilitate the useage of unleaded mogas and therefore use of that fuel requires lead to be added back in to cushion the valve seat. (This is a common sales-pitch in the automotive additives market for products such as "No-Lead" and "104+ Octane Booster" sold at parts stores and WalMart, etc...none of which contains lead, by the way. It is mostly just alcohol..an illegal additive for mogas STC's.) It is furthered by the recommendation by Mogas STC holders in suggestions to mix avgas with mogas useage.
The real changes in subsequent engine-part design was a change in valve-seat angle and valve alloys. The seat angle change was NOT to facilitate mogas use...It was done to facilitate the scavenging of the increased amount of lead in 100LL which had begun to replace 80/87 almost universally around the world. (Yet another bit of evidence, in my opinion, that lead is not good for valve and seats, for lubrication, cushion or any other purpose, but is actually a problem. In my opinion, based on years of experience first as an automotive-engine mechanic for Toyota, and later as an aircraft engine mechanic for S & S, any contaminants between a valve and it's seat will cause leakage, excessive wear, and lead to burning of that valve seal, eventually warping the valve and leading to gas-erosion and valve failure. Carbon, lead, or any other foreign object there will damage the valve/valve seat. If EAA's claim that lead is good for valve lubrication, then why would engine mfr's redesign their valves in order to get rid of/scavenge lead? Keep in mind that the new valve designs are referred to as "100 Octane" valves.)
Remember, the avgas producers AND the engine mfr's were then and are still now, opposed to mogas use,...so why would they re-design an engine for that fuel? Answer: They didn't. They did it only to lessen the bad effects of lead. There is NO benefit to lead in fuels for purposes of lubricating "upper cylinder components such as
valves, pistons, cylinder walls and
valve guides."
Next point: EAA reprint states, ".... Typically refinery supplies a large
amount “generic,†single-grade,
unleaded autogas to a pipeline
system with fuel shipped to several
storage facilities in major metropolitan
areas throughout the US.
When the fuel reaches the
storage facilities it is transferred to
tank trucks and at this time various
additives, dyes, detergents, and other
chemicals are added to the fuel give
the fuel its branded identity a grade.
No specific tracking or tracing of the
autogas is done to determine what
was added to the fuel.
I suggest that one consider how that statement jives with their other statement which they are seemingly adamant about.
EAA reprint: "Additives not certified for aircraft use should
not be added to fuels....It cannot be
stressed enough to use only additives
proven and tested for use in aircraft."
The point is that the many paragraphs devoted by them to the bad effects of undetermined additives and base stocks of mogas indicate that mogas is NOT likely to give an airplane owner the economic savings in maintenance over the long term. In other words, a penny saved now will cost plenty of dollars later on. I realize that there are many owners who anecdotally share their stories of many hours of trouble-free use of mogas. I personally know a great many who have used mogas "successfully". But the standard they measure their success by is avgas which is never a problem (especially when used with TCP), and when they have an engine or fuel system failure they are reluctant to blame the fuel that they have consciously made a choice to use.
With the uncertain quality of mogas, and with it's known traits of corrosion-causing components, and with the admitted dangers of vapor-lock problems, and the acknowleged increased danger of carburetor icing when using mogas, topped by the manufacturer's opposition to it's use and the strong warnings from even the refiners of the fuel...I can't justify it's use in my personal airplane.
The only problem I find with 100LL is excessive lead which can lead to sticking valves and short-lived spark plugs, ...both easily solved by the addition of TCP to my avgas.
Why would EAA reprint an article by LPM which promotes mogas use? Simple: They want to sell their STC's.
I can't help but wonder why, after all the comments that point to claims that "increased liabiltiy" is a cause of high av-fuel prices,...no one seems to notice that mogas STC holders don't seem to suffer from the same fears of lawsuit. Why?
I believe it's because the mogas user, with or without an STC has shouldered the blame should he pump faulty fuel into his tanks. Read the STC. It requires the "pumpee" to ascertain that the fuel meets ASTM standards, is clean, contains no "unapproved additives", etc. It's the "pumpee" that has to guarantee his fuel when he uses mogas, ...not the retailer or refiner. (Remember, they don't claim it's suitable for aircraft use!) So, it's the owner who assumes the liability/responsibility not the STC issuer.
With that in mind, it's no wonder that many mogas proponents don't bother to send EAA any money for the STC, expecially since the previous EAA STC was mistakenly allowed out into the public domain where anyone with a photocopier can get one for free. The only difference is the ASTM standard mentioned, but even that is a non-problem since the superceded ASTM (now also obsolete with the addition of ethanol) is referenced in the new one.
If you decide to use mogas in your airplane, my only suggestion is that you determine it has no alcohol in it, that it's fresh, that you deliver it into your tanks clean, that you use it soon, and that you keep a sharp lookout for deterioration of fuel system components.
(And don't forget to drain your fuel selector and carb bowl drains frequently. I will not expect your expensive and difficult-to-repair fuel selector valve and carburetor to last long..... but that's another thread.)
