From what I can see of the STC descriptions, the respective sources simply use different methods of determining the 87 octane rating. Petersen is RON+MON/2 and EAA is ASTM. Easy enough: I don't see the ASTM out here in Utah. But would that preclude me from using an ASTM supplier elsewhere?? Does it matter at all as long as it's alcohol-free? If it doesn't matter, why then are there 2 holders of the STC?
Thanks,
Todd Archer
autogas STC: EAA vs Petersen
Moderators: GAHorn, Karl Towle, Bruce Fenstermacher
Because there are technical differences between them they are not (exactly) the same STC. In any case, the ASTM standards have changed from those specified and no longer apply to that mogas commonly identified at the pump these days. So technically to use the EAA STC the pilot would have to be the person to determine that the gasoline met the specifications. (In other words, the pump will/may not spell out that particular specification for you.)
The first EAA STC has passed into public domain. Subsequently they got smarter and redid their work and produced a newer version which they can charge for. Petersen's STC never passed into public domain. But the bottom line (as I understand it) is if you have even a photocopy of the older EAA STC and can comply with it....it's a legal STC for you to use and may cost you nothing for the paperwork. (Your buddies will likely make a copy for you.)
From a practical standpoint...other than checking for alcohol....what can we do about the obsolete ASTM situation? Nothing. Regardless of which STC one may have, what they sell at the local gaspump is what is put into the tanks....hopefully with no alcohol in it.
Rhetorical question: How much effort does one wish to put into remaining legal? Is one going to carry around a chemistry set to test for ASTM standards that no longer apply to commercially available mogas? Or are you simply gonna test for alcohol (or just take a chance) and pour it in? If the second choice is yours....then it begs the question "Why have any STC at all?" If the letter of the law as regards the STC isn't being followed then it's still an illegal operation.
I have the EAA STC for my airplane. It came with the airplane when I bought it, and the airplane carries all the appropriate placards, etc. So if ever I'm in the boonies and need gas and all that's available is mogas and I need to go...then I can probably just buy whatever they're selling locally and IF a fed should see me do it and IF he should ramp check me,...at least it won't be too obvious that I'm probably still violating the law cause it's unlikely he's educated enough about the matter to know the difference anyway.
(Not referring to either of the two "fuzz" we have as members of our own little group here, who probably already knew but have now read my blabber-mouthed explanation!
Of course, they're both too-cool for us to worry about. 
)
The first EAA STC has passed into public domain. Subsequently they got smarter and redid their work and produced a newer version which they can charge for. Petersen's STC never passed into public domain. But the bottom line (as I understand it) is if you have even a photocopy of the older EAA STC and can comply with it....it's a legal STC for you to use and may cost you nothing for the paperwork. (Your buddies will likely make a copy for you.)
From a practical standpoint...other than checking for alcohol....what can we do about the obsolete ASTM situation? Nothing. Regardless of which STC one may have, what they sell at the local gaspump is what is put into the tanks....hopefully with no alcohol in it.
Rhetorical question: How much effort does one wish to put into remaining legal? Is one going to carry around a chemistry set to test for ASTM standards that no longer apply to commercially available mogas? Or are you simply gonna test for alcohol (or just take a chance) and pour it in? If the second choice is yours....then it begs the question "Why have any STC at all?" If the letter of the law as regards the STC isn't being followed then it's still an illegal operation.
I have the EAA STC for my airplane. It came with the airplane when I bought it, and the airplane carries all the appropriate placards, etc. So if ever I'm in the boonies and need gas and all that's available is mogas and I need to go...then I can probably just buy whatever they're selling locally and IF a fed should see me do it and IF he should ramp check me,...at least it won't be too obvious that I'm probably still violating the law cause it's unlikely he's educated enough about the matter to know the difference anyway.
(Not referring to either of the two "fuzz" we have as members of our own little group here, who probably already knew but have now read my blabber-mouthed explanation!
Of course, they're both too-cool for us to worry about. )
Last edited by GAHorn on Fri Aug 26, 2005 4:20 pm, edited 2 times in total.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
EAA vs Petersen STC
If I remember correctly, the Petersen STC approved unleaded auto fuel and leaded regular auto fuel while the EAA STC did not approve the regular leaded auto fuel. At least that is what I remember from when I purchased the Petersen STC for my C-140A. Wouldn't be of any benefit today since the leaded fuel is no longer refined.
correctly, the Petersen STC approved unleaded auto fuel and leaded regular auto fuel while the EAA STC did not approve the regular leaded auto fuel. At least that is what I remember from when I purchased the Petersen STC for my C-140A. Wouldn't be of any benefit today since the leaded fuel is no longer refined.OLE POKEY
170C
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170C
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
I had the Petersen STC on my last airplane, and the EAA STC on this one. They both cost a buck a horsepower. The main difference from the installation standpoint was that the Petersen STC package includes a placard in the form of an adel clamp on the engine's oil filler neck plus fuel tank placards, which are also included with the EAA STC. I believe both STC's require a check for a metal carb float. And that they both allow unleaded car gas &/or 80/87 avgas &/or 100LL avgas, or any combination thereof. But no alcohol.
[quote="gahorn"].........................................
Rhetorical question: How much effort does one wish to put into remaining legal? Is one going to carry around a chemistry set to test for ASTM standards that no longer apply to commercially available mogas? Or are you simply gonna test for alcohol (or just take a chance) and pour it in? If the second choice is yours....then it begs the question "Why have any STC at all?" If the letter of the law as regards the STC isn't being followed then it's still an illegal operation.
....................................................................
quote]
George, this is like saying that flying your 170 is an illegal operation because you have not followed the letter of the law cuz your Scott 3200 tailwheel is not installed in accordance with Scott bulletin I-168 as per TCDS requirements (item 204B). There's a thread on this subject going right now. You know, and I know, that your tailwheel installation is just fine,BUT, because the installation instructions were not carried now TO THE LETTER-- your airplane is now unairworthy & has been since you owned it! This is hairsplitting at it's finest (or worst), as the intent of the law has been followed even if you haven't crossed every t and dotted every i.
Actually, does the type certificate of the C-145/O-300 specifically approve the use of modern 100LL avgas? Maybe we're all busting the regs. I won't tell if you don't.
Eric
[quote="gahorn"].........................................
Rhetorical question: How much effort does one wish to put into remaining legal? Is one going to carry around a chemistry set to test for ASTM standards that no longer apply to commercially available mogas? Or are you simply gonna test for alcohol (or just take a chance) and pour it in? If the second choice is yours....then it begs the question "Why have any STC at all?" If the letter of the law as regards the STC isn't being followed then it's still an illegal operation.
....................................................................
quote]
George, this is like saying that flying your 170 is an illegal operation because you have not followed the letter of the law cuz your Scott 3200 tailwheel is not installed in accordance with Scott bulletin I-168 as per TCDS requirements (item 204B). There's a thread on this subject going right now. You know, and I know, that your tailwheel installation is just fine,BUT, because the installation instructions were not carried now TO THE LETTER-- your airplane is now unairworthy & has been since you owned it! This is hairsplitting at it's finest (or worst), as the intent of the law has been followed even if you haven't crossed every t and dotted every i.
Actually, does the type certificate of the C-145/O-300 specifically approve the use of modern 100LL avgas? Maybe we're all busting the regs. I won't tell if you don't.
Eric
The first EAA STC has passed into public domain. Subsequently they got smarter and redid their work and produced a newer version which they can charge for. Petersen's STC never passed into public domain. But the bottom line (as I understand it) is if you have even a photocopy of the older EAA STC and can comply with it....it's a legal STC for you to use and may cost you nothing for the paperwork. (Your buddies will likely make a copy for you.)
So where might I find one of the public domain STC's?
Todd
If you are a TIC170A member you can email headquarters@cessna170.org and Velvet will send you a copy cheap. (Something like $2 to cover copying and postage.)
Eric, that's technically correct. My tailwheel installation does not use the eyebolts per the Scott dwg, so the steering chains are not installed in accordance with the TCDS. Instead it's steering system is installed IAW the Cessna method. It might be argued the tailwheel itself is installed IAW Scott, but I doubt (and am willing to take the chance) that an FAA type or an insurance type would take issue with the matter for several reasons. The most likely reason is that no adverse effects, and no accident has or will likely be caused by the steering chain installation on my airplane. If an accident DID occur then the feds would have a much larger problem explaining why they allow Cessna to use that method.
As for the use of mogas IAW the (older) EAA STC.... the ASTM standard specified for the fuel to be used in that STC (as I understand it) simply is no longer manufactured. If it's no longer mfr'd, then the fuel being sold today doesn't meet the STC and therefore if one intends to use a different fuel (such as modern mogas) in one's airplane... then one should have an STC which is applicable to that modern fuel. Kind of a Catch-22.
Like I said before, ....I doubt if anyone fed or otherwise is going to make a big deal of it unless I kill someone important in my airplane having suffered an engine failure due to mogas, and landed on a highway and lost directional control and crashed in the ditch due to failed tailwheel steering.
Eric, that's technically correct. My tailwheel installation does not use the eyebolts per the Scott dwg, so the steering chains are not installed in accordance with the TCDS. Instead it's steering system is installed IAW the Cessna method. It might be argued the tailwheel itself is installed IAW Scott, but I doubt (and am willing to take the chance) that an FAA type or an insurance type would take issue with the matter for several reasons. The most likely reason is that no adverse effects, and no accident has or will likely be caused by the steering chain installation on my airplane. If an accident DID occur then the feds would have a much larger problem explaining why they allow Cessna to use that method.
As for the use of mogas IAW the (older) EAA STC.... the ASTM standard specified for the fuel to be used in that STC (as I understand it) simply is no longer manufactured. If it's no longer mfr'd, then the fuel being sold today doesn't meet the STC and therefore if one intends to use a different fuel (such as modern mogas) in one's airplane... then one should have an STC which is applicable to that modern fuel. Kind of a Catch-22.
Like I said before, ....I doubt if anyone fed or otherwise is going to make a big deal of it unless I kill someone important in my airplane having suffered an engine failure due to mogas, and landed on a highway and lost directional control and crashed in the ditch due to failed tailwheel steering.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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flyingfool
- Posts: 2
- Joined: Tue Aug 23, 2005 10:22 pm
Public domain EAA STC for mogas
I e-mailed headquarters and was informed they could send a copy of a petersen STC but no EAA STC and this was for a C170A--------But you would have to have authorization from Petersen to use it. Tommy----PS. I had a C170.
I thought I had added the EAA STC to the library. As soon as I return home, I'll do so. Give it another shot in about 2 weeks.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
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PilotMikeTX
- Posts: 99
- Joined: Sat Jul 02, 2005 4:46 am
Sorry not to have such a list, but on the subject of alcohol in gasoline, from the EAA:
ACTION TO BE TAKEN
In the opinion of EAA, and in the interest of most conservative operations, the following observations are offered:
If alcohol content is less than 1%, fuel will probably have no effect on aircraft.
If fuel contains up to 5% alcohol, caution must be exercised. Do not permit it to remain in tanks or fuel system for more than 24 hours, then drain and refill with alcohol-free fuel, ensuring that no alcohol concentration remains in fuel lines or sump. Vapor lock may be a problem. DO NOT FLY.
If alcohol content is more than 5%, DO NOT FLY. Drain the fuel system, flush all parts, replace with clean alcohol-free fuel and run up engine long enough to exchange fuel in carburetor bowl.
KNOWN PROBLEMS
Alcohol attacks some seal materials and varnishes on cork floats of fuel level indicators. This could cause leakage of seals and release particles of varnish from floats, causing blocked screens in fuel lines or blocked carburetor jets. Excessive entrained water carried by alcohol could lead to fuel line blockage or blockage at screens or values when operating at low ambient temperatures at ground level or at high altitude. Fuel volatility is also increased with the addition of alcohol in a manner that is not detected by the Reid Vapor Pressure test, which is used to determine if a fuel meets the automotive specification. For example, a gasoline with alcohol will meet the Reid Vapor Pressure limit of 13.5 psi but it will behave as though it has a volatility of roughly 20 psi. Gasolines with alcohol will also phase separate. Phase separation occurs as the gasoline/alcohol blend cools, such as when a plane climbs to a higher altitude. When water that is absorbed in the fuel by alcohol comes out of solution, it takes most of the alcohol with it. The quantity that comes out of solution cannot be handled by the sediment bowl and tank sumps. Furthermore, if the alcohol is used to raise the octane of the base gasoline, the gasoline that remains will not have sufficient octane to prevent detonation. A good reference for this phase separation problem is: Paul Corp., Laboratory Investigations into the Effects of Adding Alcohol to Turbine Fuel, DOT/FAA/CT-TN88/25 July 1988, FAA Technical Center, Atlantic City International Airport, NJ 08405.
http://www.eaa.org/education/fuel/oxygenated.html
To check for alcohol:
Measuring Cup Method
To nine (9) parts of the gasoline sample (36 ounces or 1 quart plus ½ cup), add 4 fluid ounces (1/2 cup) of water for a total of 40 fluid ounces in the 2-quart container. Shake thoroughly, let stand for 10 minutes or until gasoline is again bright and clear. Record the apparent level of the line between the gasoline and water.
The Measuring Cup Method is intended to indicate the presence of alcohol and is not practical to evaluate the amount of alcohol. If the final line between gasoline and water is measurably higher than the ½ cup mark, the presence of alcohol is indicated.
NOTE: Erroneous results are probable if sample and water are not thoroughly shaken and mixed.
ACTION TO BE TAKEN
In the opinion of EAA, and in the interest of most conservative operations, the following observations are offered:
If alcohol content is less than 1%, fuel will probably have no effect on aircraft.
If fuel contains up to 5% alcohol, caution must be exercised. Do not permit it to remain in tanks or fuel system for more than 24 hours, then drain and refill with alcohol-free fuel, ensuring that no alcohol concentration remains in fuel lines or sump. Vapor lock may be a problem. DO NOT FLY.
If alcohol content is more than 5%, DO NOT FLY. Drain the fuel system, flush all parts, replace with clean alcohol-free fuel and run up engine long enough to exchange fuel in carburetor bowl.
KNOWN PROBLEMS
Alcohol attacks some seal materials and varnishes on cork floats of fuel level indicators. This could cause leakage of seals and release particles of varnish from floats, causing blocked screens in fuel lines or blocked carburetor jets. Excessive entrained water carried by alcohol could lead to fuel line blockage or blockage at screens or values when operating at low ambient temperatures at ground level or at high altitude. Fuel volatility is also increased with the addition of alcohol in a manner that is not detected by the Reid Vapor Pressure test, which is used to determine if a fuel meets the automotive specification. For example, a gasoline with alcohol will meet the Reid Vapor Pressure limit of 13.5 psi but it will behave as though it has a volatility of roughly 20 psi. Gasolines with alcohol will also phase separate. Phase separation occurs as the gasoline/alcohol blend cools, such as when a plane climbs to a higher altitude. When water that is absorbed in the fuel by alcohol comes out of solution, it takes most of the alcohol with it. The quantity that comes out of solution cannot be handled by the sediment bowl and tank sumps. Furthermore, if the alcohol is used to raise the octane of the base gasoline, the gasoline that remains will not have sufficient octane to prevent detonation. A good reference for this phase separation problem is: Paul Corp., Laboratory Investigations into the Effects of Adding Alcohol to Turbine Fuel, DOT/FAA/CT-TN88/25 July 1988, FAA Technical Center, Atlantic City International Airport, NJ 08405.
http://www.eaa.org/education/fuel/oxygenated.html
To check for alcohol:
Measuring Cup Method
To nine (9) parts of the gasoline sample (36 ounces or 1 quart plus ½ cup), add 4 fluid ounces (1/2 cup) of water for a total of 40 fluid ounces in the 2-quart container. Shake thoroughly, let stand for 10 minutes or until gasoline is again bright and clear. Record the apparent level of the line between the gasoline and water.
The Measuring Cup Method is intended to indicate the presence of alcohol and is not practical to evaluate the amount of alcohol. If the final line between gasoline and water is measurably higher than the ½ cup mark, the presence of alcohol is indicated.
NOTE: Erroneous results are probable if sample and water are not thoroughly shaken and mixed.
'53 B-model N146YS SN:25713
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
50th Anniversary of Flight Model. Winner-Best Original 170B, 100th Anniversary of Flight Convention.
An originality nut (mostly) for the right reasons.
A few years ago the State of California mandated the removal of MTBE from automobile fuel due to the problem of contamination of ground water by the MTBE from leaking fuel tanks.
Fuel containing MTBE was authorized for use in aircraft that had the auto fuel STC.
Since that time all the various fuels I have tested in California contain five percent alcohol. --- Branded or unbranded, they all test out at five percent. There are no pure gasoline fuels due to the federal clean air mandates.
No problems up to now.
Fuel containing MTBE was authorized for use in aircraft that had the auto fuel STC.
Since that time all the various fuels I have tested in California contain five percent alcohol. --- Branded or unbranded, they all test out at five percent. There are no pure gasoline fuels due to the federal clean air mandates.
No problems up to now.
BL
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zero.one.victor
- Posts: 2271
- Joined: Tue Apr 23, 2002 12:11 am
I'm in rural western Washington, and I (occasionally) test for alcohol in the cargas intended for use in my airplane. Never detected any-- yet. Could be that in the big city of Seattle they aldulterate gas with alcohol and/or MTBE's for smog-reduction purposes, but (supposedly) not in the rural area where I live.
Eric
Eric